Neuromuscular Control of Human Movement
In Honour of Dave M. Koceja

 

 

 
 
 

David M. Koceja

INDIANA UNIVERSITY
BLOOMINGTON

  • Chair, Kinesiology Department
  • Associate Dean for Research, School of Public Health-Bloomington

 

Education:

  • Ph.D. at Indiana University, 1989
  • M.S. at Indiana University, 1983
  • B.S. at University of Wisconsin-Milwaukee, 1981

 

Background:

  • Director of Graduate Studies, Indiana University Department of Kinesiology, 2001-2003
  • National Institute of Aging Grant, 1996-2001
  • Eli Lilly Endowment in conjunction with Indiana University and the Pervasive Technologies Laboratory, 2004
  • Grant Reviewer, National Institutes of Health
  • Grant Reviewer, National Science Foundation
  • Indiana University School of Health, Physical Education, and Recreation Teaching and Research Award

 

Research:

·         Neuromuscular control

·         Spinal reflex system

·         Elderly

·         Motor control

·         Balance

My research interests focus on the neuromuscular control of human movement. I am currently investigating the role of the spinal reflex system in controlling normal postural sway and recovery from perturbations in elderly subjects.

The goal of these projects is to develop short- and long-term intervention programs to improve the quality of life for elderly individuals. In directing various graduate students, I have also investigated the role of dysfunctional states on neuromuscular function—particularly anterior cruciate ligament reconstruction and persons with arthritis.

Most of my research is conducted in the Motor Control Research Laboratory in the HPER building, where I work with graduate assistants to perform balance tests on older adults. Through strategically placed electrodes, we can test the response of neurons and muscles in an individual's balance and postural control.

If the tests indicate that one or more of the subject's balance systems is malfunctioning, we recommend physical activity designed to retrain neurons so the person can regain the use of dormant neurons and muscles.

Our mission is to motivate older adults to lead more active lives and enjoy better balance and health. We work in partnership with a number of groups to share the results of this research with elderly citizens in our community and with health and wellness practitioners.

 

Publications:

  •  

    2012

    Masaaki Tsuruike; Koichi Kitano; David M Koceja; Zachary A Riley

    Differential control of H-reflex amplitude in different weight-bearing conditions in young and elderly subjects.

    Clin Neurophysiol 123, 2018 (2012)
    Health Science Laboratory, Osaka University of Health and Sport Sciences, 1-1 Asashirodai, Kumatoricho, Sennangun, Osaka 590-0496, Japan. tsuruike@ouhs.ac.jp
    This study measured the modulation of conditioned (femoral nerve, paired-stimuli) and unconditioned soleus H-reflexes in young and elderly subjects when changing weight-bearing (WB) requirements and body position. METHODS: Conditioned and unconditioned H-reflexes were examined in 14 elderly subjects and 11 young subjects during six different WB conditions: (1) lying supine with no WB, (2) supine position inclined by 30° with 50% WB, (3) standing with 50%, (4) 75%, (5) 100% and (6) 125% WB. RESULTS: The elderly subjects had consistently higher background soleus EMG activity across the WB conditions compared to the young. Femoral nerve conditioning caused facilitation of the H-reflex that changed across WB conditions in the young subjects, but not in the elderly subjects. Finally, elderly subjects had less depression with paired-stimulation (PRD) across WB conditions, which was not observed in the young subjects. CONCLUSIONS: The elderly may have more direct activation of motoneurons from descending pathways, coupled with less segmental spinal control of inhibitory interneurons, as evidenced by the increased background soleus activity, H/M-max ratios and the lack of modulatory control observed when conditioning the H-reflex. SIGNIFICANCE: There was an age-specific response from descending and segmental pathways during conditions that involved either different WB requirements or changes in body position.
  •  

    2012

    Christopher T Robertson; Koichi Kitano; David M Koceja; Zachary A Riley

    Temporal depression of the soleus H-reflex during passive stretch.

    Exp Brain Res 219, 217 (2012)
    Department of Sport and Exercise Science, Jacksonville University, Jacksonville, FL 32211, USA.
    Synaptic efficacy associated with muscle spindle feedback is regulated via depression at the Ia-motoneurone synapse. The inhibitory effects of repetitive Ia afferent discharge on target motoneurones of different sizes were investigated during a passive stretch of ankle extensors in humans. H-reflex recruitment curves were collected from the soleus muscle for two conditions in ten subjects. H-reflexes were elicited during passive stretch at latencies of 50, 100, 300, and 500 ms after a slow (20°/s) dorsiflexion about the right ankle (from 100 to 90°). Control H-reflexes were recorded at corresponding static (without movement) ankle angles of 99, 98, 94, and 90° of flexion. The slope of the H-reflex recruitment curves (Hslp) was then calculated for both conditions. H-reflex values were similar for the static and passive stretch conditions prior to 50-100 ms, not showing the early facilitation typical of increased muscle spindle discharge rates. However, the H-reflex was significantly depressed by 300 ms and persisted through 500 ms. Furthermore, less than 300 ms into the stretch, there was significantly greater H-reflex depression with a lower stimulus intensity (20 % Mmax) versus a higher stimulus intensity (Hmax), though the effects begin to converge at later latencies (>300 ms). This suggests there is a distinct two-stage temporal process in the depression observed in the Ia afferent pathway for all motoneurones during a passive stretch. Additionally, there is not a single mechanism responsible for the depression, but rather both heterosynaptic presynaptic inhibition and homosynaptic post-activation depression are independently influencing the Ia-motoneurone pathway temporally during movement.
  •  

    2012

    Behdad Tahayor; Zachary A Riley; Armaghan Mahmoudian; David M Koceja; Siang Lee Hong

    Rambling and trembling in response to body loading.

    Motor Control 16, 144 (2012)
    Dept. of Kinesiology, Indiana University, Bloomington, IN, USA.
    Various studies have suggested that postural sway is controlled by at least two subsystems. Rambling-Trembling analysis is a widely accepted methodology to dissociate the signals generated by these two hypothetical subsystems. The core assumption of this method is based on the equilibrium point hypothesis which suggests that the central nervous system preserves upright standing by transiently shifting the center of pressure (COP) from one equilibrium point to another. The trajectory generated by this shifting is referred to as rambling and its difference from the original COP signal is referred to as trembling. In this study we showed that these two components of COP are differentially affected when standing with external loads. Using Detrended Fluctuation analysis, we compared the pattern of these two signals in different configurations of body loading. Our findings suggest that by applying an external load, the dynamics of the trembling component is altered independently of the area of postural sway and also independently of the rambling component. The dynamics of rambling changed only during the backloading condition in which the postural sway area also substantially increased. It can be suggested that during loaded standing, the trembling mechanism (which is suggested to be activated by peripheral mechanisms and reflexes) is altered without affecting the central influence on the shifts of the equilibrium point.
  •  

    2012

    Behdad Tahayori; Nicholas L Port; David M Koceja

    The inflow of sensory information for the control of standing is graded and bidirectional.

    Exp Brain Res 218, 111 (2012)
    Department of Kinesiology and Program in Neuroscience, Indiana University, Bloomington, IN 47405, USA. btahayor@indiana.edu
    The control of upright standing is accomplished through the integration of different sources of sensory information and by providing an appropriate motor program to control both expected and unexpected perturbations imposed on the system. However, the dynamic characteristics of postural sway and its interplay with the regulation of Ia sensory information within the spinal cord are largely unknown. Here, using a stochastic technique for analyzing the dynamics of upright standing, we demonstrate that the changes in the dynamics of postural sway were accompanied by modulation of the soleus H-reflex during quiet standing. While the causality of this relation was not established, the results showed that these changes were independent of the sway of the center of pressure and were bidirectional and purposeful. With this novel perspective, the appropriate reflex gain, which is important for balance control, can be predicted from the dynamic characteristics of postural sway. Our current findings provide the first human behavioral evidence to suggest the contribution of the spinal cord in fulfilling the desired motor programming of a complex task. This contribution is, by conventional guess, carried out through interneuronal adjustments, which are under the control of different brain areas.
  •  

    2012

    Behdad Tahayori; David M Koceja

    Activity-dependent plasticity of spinal circuits in the developing and mature spinal cord.

    Neural Plast. 2012, 964843 (2012)
    Department of Kinesiology and Program in Neuroscience, Indiana University Bloomington, Bloomington, IN 47405-7109, USA.
    Part of the development and maturation of the central nervous system (CNS) occurs through interactions with the environment. Through physical activities and interactions with the world, an animal receives considerable sensory information from various sources. These sources can be internally (proprioceptive) or externally (such as touch and pressure) generated senses. Ample evidence exists to demonstrate that the sensory information originating from large diameter afferents (Ia fibers) have an important role in inducing essential functional and morphological changes for the maturation of both the brain and the spinal cord. The Ia fibers transmit sensory information generated by muscle activity and movement. Such use or activity-dependent plastic changes occur throughout life and are one reason for the ability to acquire new skills and learn new movements. However, the extent and particularly the mechanisms of activity-dependent changes are markedly different between a developing nervous system and a mature nervous system. Understanding these mechanisms is an important step to develop strategies for regaining motor function after different injuries to the CNS. Plastic changes induced by activity occur both in the brain and spinal cord. This paper reviews the activity-dependent changes in the spinal cord neural circuits during both the developmental stages of the CNS and in adulthood.
  •  

    2011

    Najmeh Hoseini; David M Koceja; Zachary A Riley

    The effect of operant-conditioning balance training on the down-regulation of spinal H-reflexes in a spastic patient.

    Neurosci. Lett. 504, 112 (2011)
    Department of Kinesiology & Program in Neural Science, Indiana University, Bloomington, IN 47405, USA.
    Spasticity in chronic hemiparetic stroke patients has primarily been treated pharmacologically. However, there is increasing evidence that physical rehabilitation can help manage hyper-excitability of reflexes (hyperreflexia), which is a primary contributor to spasticity. In the present study, one chronic hemiparetic stroke patient operantly conditioned the soleus H-reflex while training on a balance board for two weeks. The results showed a minimal decrease in the Hmax-Mmax ratio for both the affected and unaffected limb, indicating that the H-reflex was not significantly altered with training. Alternatively, paired-reflex depression (PRD), a measure of history-dependent changes in reflex excitability, could be conditioned. This was evident by the rightward shift and decreased slope of reflex excitability in the affected limb. The non-affected limb decreased as well, although the non-affected limb was very sensitive to PRD initially, whereas the affected limb was not. Based on these results, it was concluded that PRD is a better index of hyperreflexia, and this measurement could be more informative of synapse function than simple H-reflexes. This study presents a novel and non-pharmacological means of managing spasticity that warrants further investigation with the potential of being translated to the clinic.
  •  

    2011

    Hongwei Guan; David M Koceja

    Effects of long-term tai chi practice on balance and H-reflex characteristics.

    Am. J. Chin. Med. 39, 2510 (2011)
    Department of Health Promotion and Physical Education, Ithaca College, Ithaca, NY 14850, USA. hguan@ithaca.edu
    The purpose of the present study was to examine the effects of long-term Tai Chi practice on postural balance and H-reflex. Sixteen healthy volunteers, eight with three or more years of experience in Tai Chi training (Tai Chi Group-TCG), and eight with no experience in Tai Chi training (Control Group-CG) participated in the study. Postural sways were measured under four experimental conditions: (1) Standing still with eyes open (EO); (2) Standing still with eyes closed (EC); (3) Standing and turning head to left and right with eyes open (EOT); and (4) Standing and turning head to left and right with eyes closed (ECT). Paired reflex depression (PRD) of the soleus muscle was measured under two conditions: supine and standing. Less significant postural sway was observed in the TCG than in the CG under four conditions including EO, EC, EOT, and ECT (p < 0.01). The TCG demonstrated 14.1%, 30.6%, 33.3% and 22.7% less postural sway, respectively. Significant PRD change from a supine to standing position was observed between TCG and CG (p < 0.05). A significant correlation between PRD change (from supine to standing) and years of Tai Chi practice was observed (r = 0.80, p < 0.05). The findings of this study support the positive effects of Tai Chi exercise on balance control under different conditions. Long-term Tai Chi exercisers also demonstrated different reflex modulation from a supine to standing position, and long-term Tai Chi practice may lead to a change of PRD modulation as neuroadaptation.
  •  

    2010

    Behdad Tahayori; Koichi Kitano; Siang L Hong; David M Koceja

    Amplification of background EMG activity affects the interpretation of H-reflex gain.

    J Electromyogr Kinesiol 20, 1219 (2010)
    Department of Kinesiology and Program in Neural Sciences, 74 Motor Control Lab, HPER, E 7th Street, Bloomington, IN 47405, USA. behdadt@gmail.com
    In many H-reflex studies, the modulation of the H-reflex is usually compared relative to the normal EMG activity within the muscle. Such comparisons enable the investigators to infer whether the change in the amplitude of the H-reflex was independent of normally occurring muscle activity. This interpretation of the H-reflex is regarded as H-reflex gain, a popular dependent variable in human H-reflex studies. However, in many studies to date, the muscle activity level has been determined from the same EMG signal from which the H-reflex is recorded. This leads to an important methodological consideration: measuring the ongoing normal EMG activity from the same signal might result in an inaccurate measurement, since this EMG signal will need to be minimally amplified to capture the synchronous volley of the H-reflex amplitude. In this study we examined this possibility and found that comparing the EMG activity level from the seated position to standing position yields different results (on average 8.03% in the measurement of the increase of muscle activity). This difference was both dependent on the task and also on the EMG instrumentation used. To solve this problem we suggest the bifurcation of the EMG signal from the recording electrodes with differential amplification of the signal. With this method, both the naturally occurring muscle activity and the H-reflex signal are collected from the same area of the muscle and a more accurate measurement of the H-reflex gain will be yielded.
  •  

    2010

    Arlene A Schmid; Marieke Van Puymbroeck; David M Koceja

    Effect of a 12-week yoga intervention on fear of falling and balance in older adults: a pilot study.

    Arch Phys Med Rehabil 91, 576 (2010)
    Veterans Affairs Health Services Research and Development, Center of Excellence on Implementing Evidence-Based Practice, and the Health Services Research and Development Stroke Quality Enhancement Research Initiative, Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA. Arlene.schmid@va.gov
    To determine whether fear of falling (FoF) and balance improved after a 12-week yoga intervention among older adults. DESIGN: A 12-week yoga intervention single-armed pilot study. SETTING: A retirement community in a medium-sized university town in the Midwest. PARTICIPANTS: A convenience sample of adults (N=14) over the age of 65 years who all endorsed an FoF. INTERVENTION: Each participant took part in a biweekly 12-week yoga intervention. The yoga sessions included both physical postures and breathing exercises. Postures were completed in sitting and standing positions. MAIN OUTCOME MEASURES: We measured FoF with the Illinois FoF Measure and balance with the Berg Balance Scale. Upper- and lower-body flexibility were measured with the back scratch test and chair sit and reach test, respectively. RESULTS: FoF decreased by 6%, static balance increased by 4% (P=.045), and lower-body flexibility increased by 34%. CONCLUSIONS: The results indicate that yoga may be a promising intervention to manage FoF and improve balance, thereby reducing fall risk for older adults. Rehabilitation therapists may wish to explore yoga as a modality for balance and falls programming; however, future research is needed to confirm the use of yoga in such programming.
  •  

    2010

    Salih Pinar; Koichi Kitano; David M Koceja

    Role of vision and task complexity on soleus H-reflex gain.

    J Electromyogr Kinesiol 20, 354 (2010)
    Marmara University, School of Physical Education and Sports, Istanbul, Turkey. spinar@indiana.edu
    There exists extensive evidence supporting the presence of reflex modulation in humans during a variety of motor tasks. The soleus H-reflex has been shown to be modulated during static and dynamic balance conditions as well as during various motor tasks. The purpose of this study was to examine the effects of two different stance positions and visual conditions on soleus H-reflex gain in 15 apparently healthy adults (mean age=30.27+/-6.92 yrs). The soleus H-reflexes were examined in two experimental stance conditions: two-legged (stable) and one-leg (unstable), and two visual conditions: eyes open and eyes closed. To assess the reflex gain, subjects performed ten trials under each of the four conditions and a soleus H-reflex was elicited during the performance of each trial. For each condition the peak-to-peak amplitude of the H-reflex and the EMG activity 50 ms prior to the stimulus was recorded. Differences in the peak-to-peak amplitudes of the soleus H-reflex for the experimental conditions were compared with a 2x2 (Stance x Vision) repeated measures ANOVA. The level of significance was p<0.05. Results demonstrated significant differences in reflex gain for both the vision (F(l,15)=4.87, p<0.05) and the stance condition (F(l,15)=14.86, p<0.05). Although both the stance condition and vision significantly affected the H-reflex gain, there was no interaction between these two variables (F(l,15)=0.17). From these results, we conclude that H-reflex gain was decreased both as stance complexity increased and as visual inputs were removed. Consistent with previous reports, it may be speculated that changes in presynaptic inhibition to the soleus Ia fibers regulate these gain changes. We propose that vision and stability of stance affect soleus H-reflex gain, but do so without any interactive effects.
  •  

    2010

    Rachel Ryder; Koichi Kitano; David M Koceja

    Spinal reflex adaptation in dancers changes with body orientation and role of pre-synaptic inhibition.

    J Dance Med Sci 14, 1550 (2010)
    Motor Control Laboratory, Department of Kinesiology and Program in Neuroscience, Indiana University, Bloomington, Indiana 47405, USA. rabritto@indiana.edu
    Dancers undergo specific activity-dependent neuromuscular adaptations following long-term training that allow them to develop the refined motor skills required for success in dance. The spinal stretch reflex circuit has demonstrated specific adaptations following prolonged dance training. Adaptations in the spinal stretch reflex can be studied using H-reflex methodology, first described by Paul Hoffmann in 1910. This article discusses H-reflex methodology and presents data that examine the neural mechanisms that contribute to adaptations in the spinal stretch reflex with dance training. Two groups of subjects, modern dancers (N = 5) and untrained controls (N = 5), were tested. On one-half of the trials common peronal nerve (CPN) conditioning of the soleus H-reflex was used to assess one spinal mechanism, pre-synaptic inhibition; the other half tested the soleus H-reflex only (unconditioned). The dependent variables were the H(max)/M(max) ratios, unconditioned and with CPN conditioning, expressed as percent values. The results revealed three main findings: 1. Modern dancers had smaller H(max)/M(max) ratios than control subjects; 2. The H(max)/M(max) ratio was smaller in standing posture than in prone among both dancers and controls; and 3. Pre-synaptic inhibition was not different between dancers and controls in standing. In conclusion, modern dancers have smaller H-reflexes than untrained controls, but pre-synaptic inhibition does not appear to explain this difference.
  •  

    2009

    Sarah B Goldman; Teresa L Brininger; John W Schrader; Richard Curtis; David M Koceja

    Analysis of clinical motor testing for adult patients with diagnosed ulnar neuropathy at the elbow.

    Arch Phys Med Rehabil 90, 1846 (2009)
    United States Army Research Institute of Environmental Medicine, Military Performance Division, 15 Kansas St, Building 42, Natick, MA 01760, MA, USA. Sarah.goldman@us.army.mil
    To compare the dichotomous results for 7 ulnar nerve clinical motor tests (Froment's sign, Wartenberg's sign, finger flexion sign, Jeanne's sign, crossed finger test, Egawa's sign, presence of clinical fasciculations) with motor nerve conduction velocity findings. DESIGN: A static group comparison design assessed for differences among dichotomous test outcomes with respect to motor nerve conduction velocity. SETTING: Five medical facilities throughout the United States provided data for this study. PARTICIPANTS: Records from participants (N=26) with diagnosed ulnar neuropathy at the elbow were included for data analysis. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Demographic data included age, sex, handedness, duration of symptoms, and the number of days between the clinical and electrodiagnostic exam. Other dependent variables included motor conduction velocity of the ulnar nerve, compound muscle action potential amplitude, and the dichotomous clinical motor test outcomes. RESULTS: Two motor signs, the presence of clinical fasciculations and a positive finger flexion sign, were identified more frequently (each present in 11 patients) than the other motor signs. An analysis of covariance revealed significant differences in motor nerve conduction velocity between positive and negative results for all the clinical motor tests except for the finger flexion sign. Significant chi-square analyses were found for the following comparisons: the presence of clinical fasciculations and Froment's sign, the finger flexion sign and the crossed finger test, Egawa's sign and Froment's sign, Warteberg's sign and Froment's sign, the crossed finger test and Froment's sign, and Egawa's sign and Wartenberg's sign. CONCLUSIONS: Some clinical motor tests are better than others at identifying early motor involvement, providing the rehabilitation professional some insight regarding the relative decrement of motor nerve conduction velocity when a selected test is positive.
  •  

    2009

    Sarah B Goldman; Teresa L Brininger; John W Schrader; David M Koceja

    A review of clinical tests and signs for the assessment of ulnar neuropathy.

    J Hand Ther 22, (2009)
    Department of Kinesiology, Indiana University, Bloomington, Indiana, USA. sarah.goldman@us.army.mil
    As part of a comprehensive assessment for suspected ulnar neuropathy, clinical testing plays an important role in the initial identification of a lesion and determining subsequent changes from baseline. The purpose of this article was to review ulnar nerve provocative testing and the substantial collection of diagnostic signs and tests. Administration procedures for each maneuver are described as well as the resulting positive and negative outcomes. The clinical tests described constitute only one aspect of the examination and should not substitute for other key components, such as taking a thorough medical and occupational history. Empirical research studies are indicated to further quantify the relationship between the testing outcomes and the severity of a lesion as well as to determine the most robust motor signs seen in the early stages of the disease.
  •  

    2009

    Donald W Zakutansky; Koichi Kitano; David M Koceja; Janet P Wallace

    The effect of blood flow on h-reflex and motor responses in adults with type 2 diabetes.

    J Clin Neurophysiol 26, 201 (2009)
    Clinical Exercise Physiology Laboratory, Indiana University, Bloomington, Indiana 47405, USA.
    To examine the effect of blood flow on peripheral nerve function in adults with type 2 diabetes. Ten adults with type 2 diabetes and 10 age- and body mass index-matched controls participated in the study. Soleus H-reflex and motor recruitment curves were determined for subjects at baseline, during 10 minutes of ischemia by femoral artery occlusion, and after a 10-minute bout of leg exercise. At baseline, the H-reflex threshold occurred at 77.44% +/- 1.12% and 92.23% +/- 0.04% (mean +/- SE) of motor threshold at baseline for the diabetes and control groups, respectively. During ischemia, the H-reflex threshold occurred at 72.44% +/- 7.19% and 88.79% +/- 7.80% of motor threshold at baseline for the diabetic and control groups, respectively. Following exercise, the H-reflex threshold occurred at 64.44% +/- 8.47% and 94.93% +/- 4.30% of motor threshold at baseline for the diabetes and control groups, respectively, which significantly differed from baseline. Hmax/Mmax ratios were significantly reduced with acute ischemia for the diabetes group (25.6%). Postexercise, the Hmax/Mmax ratio returned to baseline for controls while remaining significantly lower than baseline in the diabetes group. H-reflex and motor responses were hypoexcitable with an accompanying hyperemia for controls. In the diabetes group, the postexercise period resulted in a hyperexcitable H-reflex and motor response. Acute ischemia decreases H-reflex thresholds in adults with diabetes and exercise-induced increases in blood flow further decrease these thresholds. These responses are markedly more pronounced than those of their peers without diabetes and are accompanied by changes in sensory transmission to the motoneuron.
  •  

    2009

    JoEllen M Sefton; Charlie A Hicks-Little; Tricia J Hubbard; Mark G Clemens; Christopher M Yengo; David M Koceja; Mitchell L Cordova

    Sensorimotor function as a predictor of chronic ankle instability.

    Clin Biomech (Bristol, Avon) 24, 451 (2009)
    Department of Kinesiology, Auburn University, Auburn, AL 36849-5323, USA. jmsefton@auburn.edu
     Recurrent ankle injury occurs in 70% of individuals experiencing a lateral ankle sprain. The cause of this high level of recurrence is currently unknown. Researchers have begun to investigate sensorimotor deficits as one possible cause with inconclusive and often conflicting results. The purpose of this study was to further the understanding of the role of sensorimotor deficits in the chronically unstable ankle by establishing which specific measures best distinguish between chronically unstable and healthy ankles. METHODS: Twenty-two participants with chronic ankle instability and 21 healthy matched controls volunteered. Twenty-five variables were measured within four sensorimotor constructs: joint kinesthesia (isokinetic dynamometer), static balance (force plate), dynamic balance (Star Excursion Balance Test) and motoneuron pool excitability (electromyography). FINDINGS: The above variables were evaluated using a discriminant function analysis [Wilks'Lambda=0.536 chi(2)(7, N=43)=22.118, P=0.002; canonical correlation=0.681]. The variables found to be significant were then used to assess group discrimination. This study revealed that seven separate variables from the static balance (anterior/posterior and medial/lateral displacement and velocity) and motoneuron pool excitability constructs (single-legged recurrent inhibition and single- and double-legged paired reflex depression) accurately classified over 86% of participants with unstable ankles. INTERPRETATION: These results suggest that a multivariate approach may be necessary to understand the role of sensorimotor function in chronic ankle instability, and to the development of appropriate rehabilitation and prevention programs. Out of the four overall constructs, only two were needed to accurately classify the participants into two groups. This indicates that static balance and motoneuron pool excitability may be more clinically important in treatment and rehabilitation of chronic ankle instability than functional balance or joint kinesthesia.
  •  

    2009

    Koichi Kitano; David M Koceja

    Spinal reflex in human lower leg muscles evoked by transcutaneous spinal cord stimulation.

    J. Neurosci. Methods 180, 111 (2009)
    Department of Kinesiology and Program in Neuroscience, Indiana University, HPER 121 Bloomington, IN 47405, USA.
    The H-reflex is one of the most common and useful techniques in the field of motor control. However, the H-reflex technique also involves difficulty in data interpretation when stimulus intensity is high enough to stimulate both sensory and motor fibers (antidromic current). On the other hand, transcutaneous stimulation applied on the spinous processes is able to stimulate the dorsal root, resulting in selective stimulation of only sensory fibers without evoking a direct motor response and antidromic current on the motor fibers. The purpose of this study was to examine the maximal reflex response that can be elicited in the lower leg muscles using transcutaneous spinal stimulation. Seven subjects participated in the study. EMG signals were recorded from triceps surae (SOL, MG, LG) in the prone position. Transcutaneous stimulation was applied both to the spinous process (between T11 and T12, spinal stimulation, SS) and to the popliteal fossa (peripheral stimulation, PS). Using SS and PS, H(max) amplitudes of triceps surae muscles were measured and standardized with M(max). H(max) values in MG and LG by SS (31% and 41%) were significantly greater than those by PS (20% and 23%, respectively). Although not significant, H(max) amplitude in SOL by SS (76%) was also greater than that by PS (60%). It is suggested that transcutaneous stimulation is able to evoke H-reflex without a direct motor response. H(max) amplitudes traditionally measured by stimulation applied to a mixed nerve may underestimate the potential connectivity between the sensory and motor systems in humans.
  •  

    2008

    JoEllen M Sefton; Charlie A Hicks-Little; Tricia J Hubbard; Mark G Clemens; Christopher M Yengo; David M Koceja; Mitchell L Cordova

    Segmental spinal reflex adaptations associated with chronic ankle instability.

    Arch Phys Med Rehabil 89, 1991 (2008)
    Department of Kinesiology, Auburn University, Auburn, AL 36849-5323, USA.

    To further understanding of the role that segmental spinal reflexes play in chronic ankle instability (CAI). DESIGN: A 2 x 2 repeated-measures case-control factorial design. The independent variables were ankle group with 2 levels (healthy, CAI) and stance with 2 levels (single, double legged). SETTING: University research laboratory. PARTICIPANTS: Twenty-two participants with CAI and 21 matched healthy controls volunteered. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The dependent variables were 2 measures of motoneuron pool excitability: paired reflex depression (PRD) and recurrent inhibition. RESULTS: A 2 x 2 repeated-measures multivariate analysis of variance revealed a significant interaction between group and stance on the linear combination of PRD and recurrent inhibition variables (Wilks lambda=.808, F(2,40)=4.77, P=.014). Follow-up univariate F tests revealed an interaction between group and stance on the PRD (F(1,41)=9.74, P=.003). Follow-up dependent t tests revealed a significant difference between single- and double-legged PRD in the healthy participants (t(20)=-3.76, P=.001) with no difference in CAI participants (t(21)=-0.44, P=.67). Finally, there was a significant difference in recurrent inhibition between healthy (mean, 83.66) and CAI (mean, 90.27) (P=.004). CONCLUSIONS: This study revealed that, compared with healthy participants, CAI participants were less able to modulate PRD when going from a double- to a single-legged stance. Additionally, CAI participants showed higher overall levels of recurrent inhibition when compared with healthy matched controls.

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    2006

    M Tsuruike; D M Koceja; C T Robertson; K Yabe

    Implications for using H-max/M-max ratio in H-reflex parameters for elderly subjects compared with young subjects.

    Electromyogr Clin Neurophysiol 46, 285 (2006)
    Health Science Laboratory, Department of Health and Sport Management, Osaka University of Health and Sport Sciences, Osaka 590-0496, Japan. tsuruike@ouhs.ac.jp
    The H-max/M-max ratio has long been used to understand motoneuron excitability induced by the Ia fibers. However, we contend that when comparing young and elderly subjects, this measurement can be controversial. We compared the modulation of the soleus H-max and M-max at five different muscle lengths between elderly and young subjects. The young subjects demonstrated a significant modulation of both H-max and M-max between dorsiflexion (DF) and plantarflexion (PF) positions. In contrast, the elderly subjects demonstrated no difference in H-max and M-max between DF and PF positions. However, it was more interesting to note that those elderly subjects who had similar H-max/M-max ratios to the young subjects at 0 deg showed identical modulation of H-max and M-max to that of the young In this paper, we discuss that H-reflex comparisons between young and elderly subjects may be confounded by the initial H-max/M-max ratio. This finding has implications for both the statistical analysis of this data as well as the theoretical interpretation of H-reflex measurements.
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    2006

    Kristin I Stanford; Timothy D Mickleborough; Shahla Ray; Martin R Lindley; David M Koceja; Joel M Stager

    Influence of menstrual cycle phase on pulmonary function in asthmatic athletes.

    Eur. J. Appl. Physiol. 96, 703 (2006)
    Biomedical Sciences, University of California-San Diego, La Jolla, CA 92093, USA.
    The main aim of this study was to investigate whether there is a relationship between menstrual cycle phase and exercise-induced bronchoconstriction (EIB) in female athletes with mild atopic asthma. Seven eumenorrheic subjects with regular 28-day menstrual cycles were exercised to volitional exhaustion on day 5 [mid-follicular (FOL)] and day 21 [mid-luteal (LUT)] of their menstrual cycle. Pulmonary function tests were conducted pre- and post-exercise. The maximal percentage decline in post-exercise forced expiratory volume in 1 s (FEV(1)) and forced expiratory flow from 25 to 75% of forced vital capacity (FEF(25-75%)) was significantly greater (P<0.05) on day 21 (mid-LUT phase) (-17.35+/-2.32 and -26.28+/-6.04%, respectively), when salivary progesterone concentration was highest, compared to day 5 (mid-FOL phase) (-12.81+/-3.35 and -17.23+/-8.20%, respectively), when salivary progesterone concentration was lowest. The deterioration in the severity of EIB during the mid-LUT phase was accompanied by worsening asthma symptoms and increased bronchodilator use. There was a negative correlation between the percent change in pre- to post-exercise FEV(1) and salivary progesterone concentration. However, no such correlation was found between salivary estradiol and the percentage change in pre- to post-exercise FEV(1). This study has shown for the first time that menstrual cycle phase is an important determinant of the severity of EIB in female athletes with mild atopic asthma. Female asthmatic athletes may need to adjust their training and competition schedules to their menstrual cycle and to consider the potential negative effects of the LUT phase of the menstrual cycle on exercise performance.
  •  

    2005

    Donald W Zakutansky; Koichi Kitano; Janet P Wallace; David M Koceja

    H-reflex and motor responses to acute ischemia in apparently healthy individuals.

    J Clin Neurophysiol 22, 210 (2005)
    Clinical Exercise Physiology Laboratory, Indiana University, Bloomington, Indiana 47405, USA.
    The authors examined the effect of acute ischemia on peripheral nerve function in healthy subjects. It was hypothesized that acute ischemia would interfere with the ability of sensory and motor nerves to propagate an impulse. Twelve young, apparently healthy adults participated in the study. Soleus H-reflex and motor recruitment curves were determined for subjects during a control condition, after 5 minutes of ischemia by femoral artery occlusion, and after a 5-minute recovery. During ischemia, the stimulus intensity required to evoke an H-reflex or M-wave was reduced by 18.3% and 18.4%, respectively. Hmax/Mmax ratios were significantly reduced with acute ischemia (mean +/- standard error) 66.29% +/- 5.4% and 58.81% +/- 6.7% for control and ischemia, respectively, owing to a decrease in Hmax during acute ischemia with no change in Mmax. After ischemia, the Hmax/Mmax returned to control values, as did the M-threshold. However, although the H-threshold slightly recovered, it failed to return to control threshold after 5 minutes of recovery. The results suggest that acute ischemia decreases motor and H-reflex thresholds in healthy individuals with a longer lasting effect for the H-reflex. In addition, a decrease in Hmax/Mmax ratio was observed, suggesting that acute ischemia has differential effects on sensory nerve propagation and synapse transmission.
  •  

    2005

    John F Yannessa; David M Koceja

    A comparison of falls efficacy among older United States adults living independently and in group dwellings: health education implications.

    Int Q Community Health Educ 24, 65 (2005)
    Coastal Carolina University, Conway, SC 29528, USA. yannessa@coastal.edu
    The objective was to examine the relationship between a community based balance measure and perceptions of balance among individuals from different elderly living environments. The research was a cross-sectional between groups comparison design. Data collection was conducted in a community setting, in both older adult group housing facilities and in older adult community centers. Data analysis was conducted on a sample of 74 older adults that included independent and group dwellers. Instruments used to collect information from the older adults were the Berg Balance Scale and the Tinetti Falls Efficacy Scale. Results indicate that significant differences (p < .05) in Falls Efficacy by location were found (t(72) = 2.04, p = .044). Many group dwelling older adults believe their ability to perform activities of daily living (ADLs) is compromised simply as a result of their living situation. This research indicates that this fear may be unfounded. In the future, we suggest that health educators working with older adults focus their efforts on education designed to increase senior falls efficacy.
  •  

    2004

    D A Patikas; C Kotzamanidis; C T Robertson; D M Koceja

    The effect of the ankle joint angle in the level of soleus Ia afferent presynaptic inhibition.

    Electromyogr Clin Neurophysiol 44, 503 (2004)
    Department of Physical Education and Sport Science, Aristotle University of Thessaloniki, Greece.
    The factors that are responsible for the relationship between motoneuron excitability and muscle length may have both mechanical and/or neurophysiologic origins. The aim of the study was to investigate the changes in the level of presynaptic inhibition, as measured with a soleus H-reflex conditioning protocol, and muscle length. Ten healthy volunteers were measured at three different ankle angles: 30 degrees plantar flexion, neutral position (0 degrees) and 15 degrees dorsiflexion. At each position the soleus H-reflex and the maximum M-wave were measured while the limb was relaxed. The H-reflex was conditioned by a stimulation of the common peroneal nerve, 100 ms prior to the tibial nerve stimulation. The results revealed that the level of presynaptic inhibition was higher at the neutral position in comparison to the dorsiflexed or plantarflexed positions. Additionally, the HMAX/MMAX ratio was significantly decreased when the joint position was set at dorsiflexion. Further, there was a significant correlation, independent of ankle joint angle, between presynaptic inhibition levels and the HMAX/MMAX ratio. The above findings support the concept that peripheral feedback from passive, static modifications in the joint angle and consequently in muscle length, can modify the input/output threshold of the motoneurons on a presynaptic level.
  •  

    2004

    David M Koceja; Edwin Davison; Christopher T Robertson

    Neuromuscular characteristics of endurance- and power-trained athletes.

    Res Q Exerc Sport 75, 23 (2004)
    Department of Kinesiology and Program in Neural Science at Indiana University, Bloomington 47405, USA. koceja@indiana.edu
    In response to chronic physical training, the human neuromuscular system undergoes significant and specific adaptations. More importantly, these influences are the result of the type and quantity of physical activity. One of the simplest neuromuscular mechanisms is the spinal stretch reflex. The reflex system was previously viewed as inflexible, with a relatively fixed response that could vary only slightly. However, more recent data have identified an adaptive plasticity in the reflex system. In this respect, the reflex system can be used to assess training and aging adaptations of the human neuromuscular system. Due to their methodological simplicity, both the tendon-tap reflex and the electrically evoked Hoffmann reflex (H-reflex) can be used to assess training adaptations of the human neuromuscular system. The purpose of this paper is to review briefly the tendon-tap and H-reflex paradigms and delineate the research findings pertaining to changes in the reflex system with physical training. For purposes of clarity, this discussion will be divided into the following: (a) differences observed in the tendon-tap reflex, (b) differences observed in the H-reflex, and (c) role of interneurons in mediating these changes.
  •  

    2003

    B S Hale; J S Raglin; D M Koceja

    Effect of mental imagery of a motor task on the Hoffmann reflex.

    Behav. Brain Res. 142, 81 (2003)
    Department of Kinesiology, Indiana University, HPER 112, Bloomington, IN 47404, USA. brehale@indiana.edu
    Research has found that mental imagery of a motor task may influence the Hoffmann reflex (H-reflex). However, this work has not examined the potential influence of background EMG (BEMG) on the H-reflex. In this study 23 adult participants (M=23.3 years, S.D.=3.2) were instructed to mentally image plantar flexion of the right foot at four intensities: 40, 60, 80 and 100% of maximum voluntary contraction (MVC) after completing practice trials of actual contractions at these intensities. Dependent measures were the BEMG activity and the peak-to-peak amplitude of the H-reflex. On each trial the peak-to-peak amplitude of the soleus H-reflex was measured in the right leg and averaged, BEMG (40 ms bin) was measured in the soleus and tibialis anterior of both legs. Following trials of plantar flexion at the target intensities participants completed 5 imagery trials at each intensity and 15 trials while performing this motor task. Five resting control trials were administered prior to and following the completion of all test trials. Administration of test trials was randomized within conditions. A main effect (P<0.05) for trial blocks was observed for H-reflex amplitude but not BEMG. The H-reflex increased linearly throughout testing, suggesting that the H-reflex was modified by the practice of imagery rather than the intensity of the imagined task.
  •  

    2003

    Masaaki Tsuruike; David M Koceja; Kyonosuke Yabe; Norihiro Shima

    Age comparison of H-reflex modulation with the Jendrássik maneuver and postural complexity.

    Clin Neurophysiol 114, 945 (2003)
    Health Science Laboratory, Department of Health and Sport Management, Osaka University of Health and Sport Sciences, Japan. tsuruike@ouhs.ac.jp
    Research has found that mental imagery of a motor task may influence the Hoffmann reflex (H-reflex). However, this work has not examined the potential influence of background EMG (BEMG) on the H-reflex. In this study 23 adult participants (M=23.3 years, S.D.=3.2) were instructed to mentally image plantar flexion of the right foot at four intensities: 40, 60, 80 and 100% of maximum voluntary contraction (MVC) after completing practice trials of actual contractions at these intensities. Dependent measures were the BEMG activity and the peak-to-peak amplitude of the H-reflex. On each trial the peak-to-peak amplitude of the soleus H-reflex was measured in the right leg and averaged, BEMG (40 ms bin) was measured in the soleus and tibialis anterior of both legs. Following trials of plantar flexion at the target intensities participants completed 5 imagery trials at each intensity and 15 trials while performing this motor task. Five resting control trials were administered prior to and following the completion of all test trials. Administration of test trials was randomized within conditions. A main effect (P<0.05) for trial blocks was observed for H-reflex amplitude but not BEMG. The H-reflex increased linearly throughout testing, suggesting that the H-reflex was modified by the practice of imagery rather than the intensity of the imagined task.
  •  

    2003

    C T Robertson; D M Koceja

    Post-activation depression of the soleus H-reflex in the elderly.

    Electromyogr Clin Neurophysiol 43, 103 (2003)
    Motor Control Laboratory, Department of Kinesiology, Program in Neural Science, HPER 112, Indiana University, Bloomington, IN 47405, USA.
    This study examined the effect of age on the spinal mechanism post-activation depression (PD) and its relationship with postural sway. METHODS: Two groups, young (n = 10, 25.2 +/- 5.2 yr) and elderly (n = 10, 74.6 +/- 6.3 yr) participated in this study. Soleus H-reflex amplitude (peak-to-peak EMG) was measured prior to and after a passive dorsiflexion about the ankle (from 120 degrees plantarflexion to 110 degrees plantarflexion at 15 degrees/s). All H-reflex measurements were recorded at an ankle joint angle of 110 degrees. For each group, stimulus intensity was set at 25% of maximal motor response (M-max) and PD measurement intervals were randomly assigned at 0, 1, 2, 3, 4, 5, 10, 15, and 18 seconds post-movement. To ascertain whether PD was related to postural sway, standing sway area (mm2) was also measured. Subjects stood motionless (20 second duration) on a Kistler force platform during two conditions: with and without vision. RESULTS: A split-plot ANOVA (Group x Interval) indicated significant differences (F(1.18) = 14.80, p < 0.05) in PD between young and elderly, as well as a Group x Interval interaction (F(10, 180) = 16.02, p < 0.05). Simple main effects identified significant (p < 0.05) intervals at 0, 1, 2, and 3 seconds. The elderly had on average 16.1% less H-reflex depression during the first three seconds after muscle activation. Additionally, a split-plot ANOVA (Group x Condition) indicated significant differences (F(1, 18) = 10.72, p < 0.05) in sway area between young and elderly, but regression analysis indicated post-activation depression and postural sway were not significantly correlated. CONCLUSIONS: It is concluded that the integrity of the Ia-motoneuron synapse as measured with a PD protocol, is different between young and elderly subjects, but that this difference is not related to postural sway.
  •  

    2002

    Donald R Earles; Jason T Dierking; Christopher T Robertson; David M Koceja

    Pre- and post-synaptic control of motoneuron excitability in athletes.

    Med Sci Sports Exerc 34, 1766 (2002)
    Motor Control Laboratory, Department of Kinesiology, Indiana University, Bloomington, 47405, USA.
    The purpose of this study was to examine the efficacy of two spinal mechanisms in gating motoneuron excitability in power-trained athletes (N = 9), endurance-trained athletes (N = 9), and untrained subjects (N = 9). METHODS: The dependent variable for each protocol was the peak-to-peak amplitude of the conditioned soleus Hoffmann reflex (H-reflex). Modulations of the test reflex amplitude were evaluated for each subject by using two experimental conditioning protocols: recurrent inhibition (RI) and paired-reflex depression (PRD). Also, to assess the effects of different levels of input on motoneuron excitability, two H-reflex stimulus intensities were used (10% and 30% of maximal motor response (M-max)). For each protocol, seven conditioned H-reflex trials were obtained from each subject during quiet stance. The RI protocol consisted of two reflex responses that were separated by 10 ms. The first was of the same intensity as the unconditioned trials. The second stimulus was of an intensity great enough to elicit a supramaximal motor response. The PRD protocol utilized two reflex stimuli of the same intensity separated by 80 ms. A group by intensity (3 x 2) analysis of variance was performed to determine group differences within each condition. RESULTS: For both protocols, increases in stimulus intensity resulted in significantly greater inhibition. Significant differences were observed between the trained groups for both the RI and the PRD protocols. For the RI protocol, the endurance-trained athletes demonstrated significantly less RI than either the power-trained athletes or the untrained subjects. For the PRD protocol, the endurance-trained athletes demonstrated significantly greater PRD than either the power-trained athletes or the untrained subjects. CONCLUSIONS: These observations indicate differential control of motoneuron excitability as a result of segmental reflex pathways among differently trained athletes.
  •  

    2002

    Richard G Mynark; David M Koceja

    Down training of the elderly soleus H reflex with the use of a spinally induced balance perturbation.

    J. Appl. Physiol. 93, 127 (2002)
    Motor Control Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill 27599, USA. mynark@email.unc.edu
    The purpose of this study was to determine the ability of the elderly central nervous system to modulate spinal reflex output to functionally decrease a spinally induced balance perturbation. In this case, the soleus H reflex was used as the source of perturbation. Therefore, decreasing (down training) of the soleus H reflex was necessary to counteract this perturbation and to better maintain postural control. In addition to assessing the effect of this perturbation on the H reflex, static postural stability was measured to evaluate possible functional effects. Ten healthy young subjects (age: 27.0 +/- 4.6 yr) and 10 healthy elderly subjects (age: 71.4 +/- 5.1 yr) participated in this study. Subjects underwent balance perturbation on 2 consecutive days. On day 1 of perturbation, significant down training of the soleus H reflex was demonstrated in both young (-20.4%) and elderly (-18.7%) subjects. On day 2 of perturbation, significant down training of the soleus H reflex was again demonstrated in both young (-24.6%) and elderly (-21.0%) subjects. Analysis of static stability after the 2 days of balance perturbation revealed a significant 10.1% decrease in the area of sway in elderly subjects. In conclusion, this study demonstrated that healthy, elderly subjects compared with young subjects were equally capable of down training the soleus H reflex in response to a balance perturbation. Furthermore, the improvement in static stability through balance training may provide further evidence that balance can be retrained and rehabilitated in subjects with decreased reflex function.
  •  

    2002

    D Patikas; C Michailidis; H Bassa; C Kotzamanidis; S Tokmakidis; S Alexiou; D M Koceja

    Electromyographic changes of agonist and antagonist calf muscles during maximum isometric induced fatigue.

    Int J Sports Med 23, 285 (2002)
    Department of Physical Education and Sport Science, Aristotle University of Thessaloniki, Thessaloniki, Greece. dpatikas@phed.auth.gr
    The purpose of this study was to examine electromyographic changes of the agonist and antagonist muscles during fatigue. Nine healthy, untrained subjects exerted a maximum voluntary heel lifting contraction with their dominant limb. The EMG activity over the soleus and the tibialis anterior muscles was recorded during the contraction. The results showed that the torque output during heel lifting and the soleus EMG activity decreased, whereas the tibialis anterior EMG revealed a small but non-significant decrease. However, the ratio of the tibialis anterior to the soleus EMG increased significantly at the end of the fatigue protocol, a fact that reveals that the decrease rate of the antagonist's activity was significantly lower than the decrease rate of the agonist activity. It is concluded that during a maximal fatigue protocol, both the agonist and antagonist muscle activity may decline, however, the slower rate of antagonist's activity decrease relative to the agonist's activity is a finding that requires further investigation. This finding may reflect a higher level of agonist and antagonist muscle co-activation and probably a relatively higher opposing torque from the antagonist muscles at the end of the fatigue session.
  •  

    2002

    D R Earles; H H Morris; Chao-Ying J Peng; D M Koceja

    Assessment of motoneuron excitability using recurrent inhibition and paired reflex depression protocols: a test of reliability.

    Electromyogr Clin Neurophysiol 42, 159 (2002)
    Motor Control Laboratory, Department of Kinesiology, Program in Neural Science, Indiana University, Bloomington, IN 47405, USA. dearles@indiana.edu
    Motor output may be regulated by both pre- and post-synaptic mechanisms. The purpose of this study was to investigate the reliability of two measurement protocols, which purport to examine spinal mechanisms responsible for gating motoneuron excitability. Nine subjects (aged 29 +/- 5 years) were tested using two soleus H-reflex protocols; 1) recurrent inhibition (RI) and 2) paired reflex depression (PRD). The dependent variable for each protocol was the peak-to-peak amplitude of the conditioned Hoffmann reflex (H-reflex). Seven trials were obtained for each subject under each condition as well as control values to assess test-retest reliability. After all trials were collected the subjects rested for at least five minutes after which the process was repeated. Each subject returned to the lab after a period of no less than 24 hours at which time the process was repeated. Protocol #1: Control reflexes (20% of maximal motor response) were obtained during quiet stance. After obtaining control trials two reflex responses were elicited which were separated by 10 ms on each trial to assess recurrent inhibition (Pierrot-Deseilligny et al., 1976; Bussel and Pierrot-Deseilligny, 1977). Protocol #2: Again a double-pulse technique was used to assess reflex activation history on motoneuron pool output (Trimble et al., 2000). This protocol utilized two reflex stimuli of the same intensity separated by 80 ms. The peak-to-peak amplitude of the control, RI conditioned and PRD conditioned H-reflexes exhibited intraclass reliability estimates of .97, .97 and .93 respectively. To achieve a reliability of rI > or = .80, it is recommended that a minimum of 2 trials be used for the RI protocol and that 4 trials be used for the PRD protocol. The results indicate that both techniques provide a means to objectively and reliably measure spinal mechanisms for gating motoneuron pool output.
  •  

    2001

    D Earles; V Vardaxis; D Koceja

    Regulation of motor output between young and elderly subjects.

    Clin Neurophysiol 112, 1273 (2001)
    Motor Control Laboratory, Department of Kinesiology and Program in Neural Science, HPER 112, Indiana University, Bloomington, IN 47405, USA.
    Considerable information exists concerning the differences in motoneuron pool (MP) excitability between young and elderly subjects. A recent study demonstrated decreased heteronymous Ia facilitation with aging, suggesting increased presynaptic inhibition (PI) with increasing age as a mechanism for this change (Morita et al., Exp Brain Res 104 (1995) 167). It has been suggested that during voluntary movement, supraspinal, and possibly, segmental mechanisms (Hultborn et al., J Physiol 389 (1987) 757) modulate this inhibition. It is theorized that PI can modulate the recruitment gain of the MP during movement without altering the excitability of the motoneurons. Therefore, the purpose of this study was to examine the roles of PI and volitional volleys in modulating MP output in young and elderly subjects. METHODS: Twenty apparently healthy females participated in this study, 10 college aged (mean age, 22.4+/-2.8 years) and 10 independent, community dwelling elderly (mean age, 77.6+/-5.4 years). All subjects were tested in a semi-recumbent position. H-reflexes were elicited at rest, and at 10 and 20% of maximal voluntary contraction. To assess MP output, background electromyography (EMG) was monitored prior to stimulation. The stimulus intensity was adjusted during volitional contractions to ensure similar control reflexes (25% of the maximal motor response (M-max)) at each level of contraction. RESULTS: Control reflexes at each level of volitional contraction (rest, 10 and 20%) were similar for both groups. To assess PI and to estimate the extent to which a change in the H-reflex amplitude reflects a change in MP gating, the common peroneal nerve was stimulated at 1.5 times the motor threshold 100 ms prior to stimulation of the tibial nerve. Significantly greater PI was observed for the young subjects at rest (5 vs. 13% M-max). At both 10 and 20% levels of voluntary contraction, the conditioned reflex was significantly different from rest for the young subjects. The elderly subjects, in contrast, failed to modulate the conditioned reflex until the 20% of maximal voluntary contraction (MVC) condition. When examining the recruitment gain in the MP during the PI condition (H-reflex amplitude as a function of EMG levels), a significant group effect was observed, with the young subjects demonstrating significantly higher PI gain. CONCLUSIONS: These results indicate differential control of MP output (e.g. PI vs. volitional volleys) in young and elderly subjects.
  •  

    2000

    D R Earles; D M Koceja; C W Shively

    Environmental changes in soleus H-reflex excitability in young and elderly subjects.

    Int. J. Neurosci. 105, 1 (2000)
    Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington 47405, USA.
    The purpose of this study was to examine the role of task complexity on soleus H-reflex modulation in young and elderly subjects. Twelve young (mean age = 29.2yrs) and 10 elderly (mean age = 75.1 yrs) apparently healthy individuals were examined under four experimental conditions: (1) eyes open on normal floor surface; (2) eyes open on foam floor surface; (3) eyes closed on normal floor surface; and (4) eyes closed on foam surface. Under each condition, soleus H-reflexes, and background electromyography (EMG) (40 ms window prior to stimulation in both the soleus and the tibialis anterior) were recorded. Postural sway in each condition was also assessed using a Kistler force platform. Results indicated differential reflex modulation between young and elderly subjects. Specifically, young subjects depressed the amplitude of the reflex as task complexity was increased. Elderly subjects, on the other hand, increased the amplitude of the H-reflex when utilizing visual cues, but decreased H-reflex amplitude when vision was occluded. Postural sway in both groups increased as task complexity was increased. There existed a significant difference in the relationship between tibialis anterior activation and soleus H-reflex between the two groups. These results demonstrate differential reflex adjustments between young and elderly subjects as task complexity is increased, and may provide useful information pertaining to postural control in the elderly.
  •  

    2000

    D M Koceja; R G Mynark

    Comparison of heteronymous monosynaptic Ia facilitation in young and elderly subjects in supine and standing positions.

    Int. J. Neurosci. 103, 1 (2000)
    Motor Control Laboratory, Department of Kinesiology and Program in Neural Science, HPER 112, Indiana University, Bloomington, IN 47405, USA. koceja@indiana.edu
    The control of posture and balance is a primary concern among the elderly. Postural instability has been identified as a contributor to the greater incidence of falling among this segment of the population. One important neuromuscular mechanism identified as important in the control of posture and balance is the segmental reflex system. The purpose of this study was to examine the role of presynaptic inhibition in modulating the reflex system in young and elderly subjects. METHODS: To estimate the influence of body position on presynaptic inhibition to the soleus motor pool between young and elderly subjects, 11 young (mean age=23.9 yrs.) and 9 elderly (mean age=72.1 yrs.) subjects were examined in two different body positions: supine and standing. This study utilized the heteronymous facilitation protocol, as described by Hultborn et al. (1987), to estimate presynaptic inhibition of the Ia afferent pathway onto the soleus alpha-motoneuron pool. Maximal soleus H-reflex (H-max) and motor response (M-max) amplitudes were determined prior to testing at each condition, and the H-max/M-max ratio at each body position was determined. To estimate presynaptic inhibition at each body position, subjects received 24 test soleus H-reflex stimuli ( approximately 15% M-max), and 24 soleus H-reflexes conditioned by stimulation of the ipsilateral femoral nerve. RESULTS: Results demonstrated a significant decrease in H-max/M-max ratio from supine (66.1%) to standing (56.8%) for the young subjects, whereas the elderly subjects demonstrated no changes in the H-max/M-max ratio between body positions (39.8% supine; 39.8% standing). The conditioning stimulus produced a significant change in the test reflex for the young subjects during supine testing (51.1% increase) but not standing (3.4% increase). The elderly subjects demonstrated no significant changes in the test reflex produced by the heteronymous conditioning at either condition (17.6% increase supine; 4.9% increase standing). CONCLUSIONS: These results demonstrate differential effects of both H-reflex modulation and heteronymous conditioning for elderly subjects when compared with young adults. These differences may be an adaptive phenomenon of the aging neuromuscular system, exemplified by a decreased ability to modulate the reflex system in the elderly group.
  •  

    1999

    D M Koceja; D Allway; D R Earles

    Age differences in postural sway during volitional head movement.

    Arch Phys Med Rehabil 80, 1537 (1999)
    Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington 47405, USA.
    To examine the role of a volitional self-paced head-turn movement on the postural sway characteristics of healthy young and elderly subjects. DESIGN: Cross-sectional design. SETTING: Motor control research laboratory. SUBJECTS: Ten young adults and 10 elderly subjects. MAIN OUTCOME MEASURES: Postural sway characteristics of each subject were examined using a Kistler force platform. Each subject was tested under four experimental conditions: (1) static postural sway with vision; (2) static postural sway without vision; (3) postural sway with vision and self-paced head-turn movement; and (4) postural sway with no vision and a self-paced head-turn movement. Subjects performed six 15-second trials in each experimental condition. Dependent variables analyzed on each trial were mean sway amplitude (in millimeters), sagittal sway standard deviation, lateral sway standard deviation, and frequency of sway (in hertz). RESULTS: During the static conditions (e.g., no voluntary movement), the young subjects produced significantly less postural sway than the elderly in both the vision condition (sway amplitude in the young, 3.80 mm; in the elderly, 4.89 mm) and the no-vision condition (young, 5.44 mm; elderly, 5.95 mm). This increased sway was the result of greater lateral sway in the elderly for the vision condition (3.73 vs. 2.68 mm), and greater sagittal sway for the elderly in the no-vision condition (5.55 vs. 4.70 mm). There were no significant differences between the groups in the frequency of sway. When asked to initiate and complete the head-turn, elderly subjects significantly increased their mean sway amplitude and decreased their frequency of sway, whereas the young subjects did not significantly alter their postural sway profiles. CONCLUSIONS: These results demonstrate different postural sway control strategies for young and elderly subjects when asked to perform volitional movements.
  •  

    1999

    M Tsuruike; D M Koceja

    Conditioned patellar tendon-tap reflexes in patients with ACL reconstruction.

    Int J Sports Med 20, 263 (1999)
    Department of Kinesiology, Indiana University, Bloomington, USA. tsuruike@ouhs.ac.jp
    The patellar tendon-tap stretch reflexes were examined in six neurologically healthy young subjects (mean age = 27.1 yrs) who had developed persistent quadriceps strength deficit due to ACL reconstruction. Each subject was tested on two separate days. A specially designed apparatus was used to examine the unilateral and conditioned patellar tendon-tap reflex response utilizing three different conditioning intervals: 25 ms, 75 ms, 150 ms, and a unilateral reflex (control). Peak isometric force and contraction time were measured by using a strain gauge. Also, peak-to-peak EMG was measured by using bipolar surface electrodes which were placed over the middle of the rectus femoris. All data were collected with a microcomputer (sample rate = 1 kHz). Due to the small sample, the Kruskal-Wallis nonparametric analysis of variance was performed. All subjects demonstrated quadriceps strength deficits in the ACL leg when compared with the contralateral leg. This analysis determined that for both the ACL leg and the Non ACL leg the size of stretch reflex was facilitated at the long-latency conditioning intervals (75 and 150 ms), whereas it was inhibited at the short-latency conditioning interval (25ms). However, the ANOVA model failed to reveal any differences in the conditioned stretch reflex between the ACL leg and the Non ACL leg. Also, no differences were observed at the unilateral condition. Taken together, these results indicate that ACL reconstruction results in significant strength deficits, but does not alter unilateral or conditioned reflex profiles.
  •  

    1998

    R M Angulo-Kinzler; R G Mynark; D M Koceja

    Soleus H-reflex gain in elderly and young adults: modulation due to body position.

    J. Gerontol. A Biol. Sci. Med. Sci. 53, (1998)
    Department of Kinesiology, Indiana University, Bloomington, USA.
    The control of posture and balance in the elderly is a primary health concern. Postural instability directly leads to a greater incidence of falling in the elderly population. One important neuromuscular mechanism instrumental in the control of posture and balance is the reflex system. The purpose of this study was to examine the gain of the soleus H-reflex in young and elderly adults in two different body positions: standing and prone. METHODS: Eighteen neurologically healthy volunteers were categorized by age in two groups: young (n = 9, mean age = 23.3 yr) and elderly (n = 9, mean age = 71.7 yr). In each position, the resting H-max/M-max ratio was determined. The gain of the reflex was also assessed by instructing the subject to perform voluntary contractions of 10, 20 and 30% of their maximum voluntary contraction, using real-time EMG biofeedback. Data were sampled on-line using custom designed software (sample rate = 2 kHz). Dependent variables included the average background EMG of the soleus muscle (40 ms window prior to stimulation) and the peak-to-peak amplitude of the elicited soleus H-reflex. To examine the gain of the reflex, the peak-to-peak amplitude of the H-reflex was plotted against the background EMG activity for each contraction intensity. RESULTS: Results indicated the following: young subjects significantly depressed the H-max/M-max ratio when standing (69.3% prone, 55.1% standing), whereas elderly subjects increased the ratio (36.1% prone, 54.5% standing). Also, the young subjects modulated the gain of the reflex from prone to standing (3.30 prone, 3.68 standing), and the elderly subjects demonstrated no gain modulation in the different body positions (2.23 prone, 1.91 standing). In both body positions the young subjects demonstrated significantly higher gain that the elderly subjects. CONCLUSIONS: The results demonstrate different control strategies for young and elderly subjects between prone and standing body positions.
  •  

    1997

    R G Mynark; D M Koceja; C A Lewis

    Heteronymous monosynaptic Ia facilitation from supine to standing and its relationship to the soleus H-reflex.

    Int. J. Neurosci. 92, 171 (1997)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA. rmynark@indiana.edu
    To measure changes in presynaptic inhibition, 10 subjects (5 male, 5 female) were tested under two conditions: supine and standing. This study utilized the heteronymous facilitation protocol, as described by Hulborn et al. (1987a), to measure presynaptic inhibition of the Ia afferent pathway onto the soleus alpha-motoneuron pool. The magnitude of the facilitation produced by the conditioning stimulus provides an indirect assessment of presynaptic inhibition from supine to standing. Maximal soleus H-reflex (H-max) and motor response (M-max) amplitudes were determined prior to testing at each condition. Subjects received 24 test H-reflex stimuli (approximately 15% M-max), and 24 conditioned stimuli at each body position. Results demonstrated a significant decrease in H-max/M-max ratio from supine (68.7%) to standing (54.8%). This was the result of changes in H-max between the two body positions with no significant changes in M-max. Significant inhibition of the conditioned H-reflex was also demonstrated from supine to standing (30.7% M-max vs 17.5% M-max). Furthermore, it was demonstrated that a strong correlation (r = .85) existed between individual changes in H-max/M-max ratio and the changes in facilitation of the conditioned H-reflex from supine to standing. This relationship helps explain the modulation of the H-reflex during static changes in body position, and it could also provide insight into the reflex modulation associated with more functional activities such as walking or running. These results are consistent with the hypothesis that presynaptic inhibition increases as body position is changed from supine to standing.
  •  

    1997

    W F Brechue; D M Koceja; J M Stager

    Acetazolamide reduces peripheral afferent transmission in humans.

    Muscle Nerve 20, 1541 (1997)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA.
    Carbonic anhydrase has been localized in skeletal muscle and nerve, thus, inhibition with acetazolamide (ACZ) may alter nerve and/or muscle function in healthy humans. ACZ (3 oral doses 14, 8, and 2 h prior to testing) reduced isometric force (37%) and peak to peak electromyographic (EMG) amplitude (1.38 mV to 0.83 mV), while increasing EMG latency associated with a unilateral Achilles tendon-tap. Reflex recovery profiles, following a contralateral conditioning tap, were similar in both placebo and ACZ experiments. ACZ led to significant changes in Hmax/Mmax ratio (52.19/14.42 to 45.73/15.65) and H-reflex latency (34.18 +/- 2.54 ms to 35.24 +/- 2.74 ms). Motor nerve conduction velocity and maximal voluntary isometric torque (knee extensors) were unaltered by ACZ. These data suggest that inhibition of the tendon-tap reflex and associated isometric force, following ACZ, is related to impairment of synaptic integrity between la fibers of the muscle spindle and the alpha motor neuron and not impairment of the muscle spindle or force-generating capacity.
  •  

    1997

    R G Mynark; D M Koceja

    Comparison of soleus H-reflex gain from prone to standing in dancers and controls.

    Electroencephalogr Clin Neurophysiol 105, 135 (1997)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA. rmynark@indiana.edu
    To examine the differences in soleus H-reflex gain between trained dancers and control subjects, the soleus H-reflex amplitude and background muscle activity of 9 trained dancers (means of 20.3 +/- 2.1 years of age, and 14.3 +/- 3.8 years of training) and 9 control subjects (mean 23.3 +/- 3.2 years of age) were compared at rest and at 10, 20, and 30% of a maximal voluntary soleus contraction during two conditions: prone and standing. The ratio of the maximal H-reflex (H-max) to the maximal motor response (M-max) was also measured during both conditions. Correlation was performed between background EMG and the resultant H-reflex to determine reflex gain. The results demonstrated that the control subjects and the dancers displayed a similar reflex gain during the prone condition (slope = 3.30 vs. 3.64, respectively). However, during the standing condition, dancers demonstrated a significantly lower reflex gain (slope = 1.78) than did control subjects (slop = 3.68). Furthermore, although both groups significantly decreased the H-max/M-max ratio from prone to standing, no differences were found between groups at either condition. This suggests that the differences in standing reflex gain between the dancers and control subjects were a product of differential control of reflex modulation involved in postural control. An initial hypothesis explaining the differences between the standing reflex gain of the groups relates to plasticity of central inhibitory control mechanisms, primarily presynaptic and/or reciprocal inhibition.
  •  

    1997

    M A Hoffman; D M Koceja

    Dynamic balance testing with electrically evoked perturbation: a test of reliability.

    Arch Phys Med Rehabil 78, 290 (1997)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA.
    To investigate the reliability of a newly developed perturbation protocol for assessing dynamic balance. DESIGN: Each subject was tested in two experimental balance conditions, static and dynamic. The dependent variables for the static condition were sway area (SA), sway path length (SPL), sagittal sway standard deviation (SSD), and lateral sway standard deviation (LaSD). During the dynamic condition trials a stimulus was delivered to the tibial nerves of both legs to perturb the subjects. The subjects were instructed to return to the pre-perturbation level of steadiness as soon as possible after the stimulation. The dependent variables for the dynamic condition were dynamic phase duration (DPD), sway path mean (SPM), linear sway standard deviation (LiSD), and sagittal sway standard deviation (SSD). SETTING: The motor control laboratory of a university department of kinesiology. PATIENTS: Ten subjects from a population-based sample of healthy adults. MAIN OUTCOME MEASURE: An intraclass reliability estimate for all dependent measures in the static and dynamic conditions. RESULTS: In the static condition, the variables SA, SPL, SSD, and LaSD had reliabilities of .94, .98, .86, and .92, respectively, and in the dynamic condition the reliability estimates for DPD. SPM, LiSD, and SSD were .90, .71, .80, and .92, respectively. CONCLUSIONS: The results indicate the current technique provides a means of objectively measuring a subject's ability to regain static postural stability following electrically induced perturbation.
  •  

    1996

    J R Burke; M C Schutten; D M Koceja; G Kamen

    Age-dependent effects of muscle vibration and the Jendrassik maneuver on the patellar tendon reflex response.

    Arch Phys Med Rehabil 77, 600 (1996)
    Motor Control Laboratory, Indiana University, IN, USA.
    To explore possible effects of aging on the excitability of spinal reflexes. DESIGN: Using a cross-sectional design, the influences of muscle vibration and the Jendrassik maneuver on patellar tendon reflex function were compared between 30 young adults and 15 older adults. SETTING: Motor control research laboratory. SUBJECTS: The young adults were volunteers of college age. The older adults (74.5 +/- 4.14 yr) were volunteers from the local community. All subjects were free of medications and neurological conditions that would affect normal neuromuscular responses. MAIN OUTCOME MEASURES: A force-time curve analysis of the patellar tendon reflex response was used to assess the inhibition and facilitation of spinal reflexes. In the experimental protocol to assess spinal reflex inhibition, 100 Hz vibration was applied to the right quadriceps muscle. In another experimental protocol, spinal reflex facilitation was assessed using the Jendrassik maneuver. To perform the Jendrassik maneuver, subjects were instructed to grasp their hands together and to pull as hard as possible while breathing normally. After a 2-second count, the tendon tap was delivered to the right leg and the subject was instructed to relax. In both experimental protocols, control patellar tendon reflexes were collected. RESULTS: Analysis of variance for reflex peak force revealed a significant 30% reduction in the amount of vibration-induced reflex inhibition with increasing age, and a similar 33% reduction in the amount of Jendrassik maneuver facilitation observed for the older adults as compared with the younger adults. CONCLUSION: These results support the hypothesis that inhibitory and excitatory influences acting on the alpha motoneuron pool are different in young and older adults.
  •  

    1996

    J S Raglin; D M Koceja; J M Stager; C A Harms

    Mood, neuromuscular function, and performance during training in female swimmers.

    Med Sci Sports Exerc 28, 372 (1996)
    Department of Kinesiology, Indiana University-Bloomington 47401, USA.
    The effect of seasonal changes in training load on mood, neuromuscular function, and measures of physical power were examined in 12 collegiate women swimmers. These subjects were studied at three training stages during a competitive swim season: baseline (5,000 m.d-1), peak training (8,300 m.d-1), and taper (2,300 m.d-1). Mood was evaluated with the Profile of Mood States. Neuromuscular function was measured via the soleus Hoffmann-reflex (H-reflex). Anaerobic swimming power was assessed with a 30-s tethered swim test, and maximal aerobic power was determined following a maximal 378-m swim. Repeated measures ANOVA revealed that at peak training H-reflex and peak anaerobic swimming power were reduced (P < 0.05) below baseline values by 8.6% and 9.4%, respectively, and total mood disturbance was elevated above baseline (P < 0.01). These variables returned to baseline values at the taper assessment. H-reflex values were correlated with peak (r = 0.52, P < 0.01) and mean (r = 0.39, P < 0.05) anaerobic swimming power. Total mood disturbance was correlated (r = -0.34, P < 0.05) with mean swimming power. The results suggest that neurological mechanisms play a role in the adaptations that result from periodized training.
  •  

    1995

    D M Koceja; C A Markus; M H Trimble

    Postural modulation of the soleus H reflex in young and old subjects.

    Electroencephalogr Clin Neurophysiol 97, 387 (1995)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA.
    The influence of different static postures on the soleus H reflex was assessed in 15 old (mean age = 76.3 years) and 10 young (mean age = 24.2 years) subjects. H reflex and M wave recruitment curves were obtained under 2 randomly administered conditions: (1) standing; and (2) prone. Once in place, the recording and stimulating electrodes were not removed until the completion of testing, to ensure that exact placement was maintained. A 1 msec current pulse was given transcutaneously to elicit the H reflex and M response. Static postural sway area (cm2) was assessed on a Kistler force platform using custom software (sample rate = 50 Hz/15 sec trials). Results demonstrated that the young subjects reduced the amplitude of the H reflex from the prone (Hmax/Mmax = 73.6%) to the standing (Hmax/Mmax = 59.9%) condition, whereas the old subjects did not (prone = 32.4%, standing = 38.2%). However, within the old group, 2 subgroups emerged--those who depressed the reflex similar to the young subjects (O-D, n = 6) and those who did not depress the reflex (O-ND, n = 9). Furthermore, there were significant differences in postural sway scores between the young and old, between the O-D and O-ND, but not between the O-D and young groups. These results suggest differences in the manner in which young and old subjects modulate the soleus H reflex when standing, and support the view that modulation of the stretch reflex may be important in the control of static posture.
  •  

    1995

    M A Hoffman; D M Koceja

    The effects of vision and task complexity on Hoffmann reflex gain.

    Brain Res. 700, 303 (1995)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA.
    Previous research demonstrates modulation of the Hoffmann reflex amplitude and gain during changes in environmental conditions. H-reflex gain (defined in this study as the ratio of H-reflex amplitude to average soleus background EMG) is considered a functional measure of reflex modulation. In this study the effects of manipulating visual input and surface stability were to investigated in 17 subjects under four experimental conditions: (1) vision-stable surface, (2) no vision-stable surface, (3) vision-unstable surface, and (4) no vision-unstable surface. In each condition, subjects performed fifteen trials of a single leg stance for 7 s. The H-reflex was electrically elicited at the end of each trial by delivering a 1 ms square wave stimulation to the tibial nerve in the popliteal online for each trial (sampling rate = 2 kHz). An analysis of variance revealed significant decreases in H-reflex gain for the visual (F1.16 = 4.71, P < 0.05) and, surface conditions (F1.16 = 7.67, P < 0.05), however there was no interaction (F1.16 = 0.48, P < 0.05), between these variables. These results suggest that supraspinal mechanisms, possibly presynaptic inhibition, modulate H-reflex gain across environmental conditions. We conclude that visual and possibly cutaneous inputs were responsible for driving presynaptic inhibition and thus decreasing H-reflex gain.
  •  

    1995

    J M Lazar; D M Koceja; H H Morris

    Effects of auditory radio interference on a fine, continuous, open motor skill.

    Percept Mot Skills 80, 739 (1995)
    Department of Kinesiology, Indiana University, USA.
    The effects of human speech on a fine, continuous, and open motor skill were examined. A tape of auditory human radio traffic was injected into a tank gunnery simulator during each training session for 4 wk. of training for 3 hr. a week. The dependent variables were identification time, fire time, kill time, systems errors, and acquisition errors. These were measured by the Unit Conduct Of Fire Trainer (UCOFT). The interference was interjected into the UCOFT Tank Table VIII gunnery test. A Solomon four-group design was used. A 2 x 2 analysis of variance was used to assess whether interference gunnery training resulted in improvements in interference posttest scores. During the first three weeks of training, the interference group committed 106% more systems errors and 75% more acquisition errors than the standard group. The interference training condition was associated with a significant improvement from pre- to posttest of 44% in over-all UCOFT scores; however, when examined on the posttest the standard training did not improve performance significantly over the same period. It was concluded that auditory radio interference degrades performance of this fine, continuous, open motor skill, and interference training appears to abate the effects of this degradation.
  •  

    1995

    D M Koceja

    Quadriceps mediated changes in soleus motoneuron excitability.

    Electromyogr Clin Neurophysiol 35, 25 (1995)
    Department of Kinesiology, Indiana University, Bloomington 47405, USA.
    The effects of human speech on a fine, continuous, and open motor skill were examined. A tape of auditory human radio traffic was injected into a tank gunnery simulator during each training session for 4 wk. of training for 3 hr. a week. The dependent variables were identification time, fire time, kill time, systems errors, and acquisition errors. These were measured by the Unit Conduct Of Fire Trainer (UCOFT). The interference was interjected into the UCOFT Tank Table VIII gunnery test. A Solomon four-group design was used. A 2 x 2 analysis of variance was used to assess whether interference gunnery training resulted in improvements in interference posttest scores. During the first three weeks of training, the interference group committed 106% more systems errors and 75% more acquisition errors than the standard group. The interference training condition was associated with a significant improvement from pre- to posttest of 44% in over-all UCOFT scores; however, when examined on the posttest the standard training did not improve performance significantly over the same period. It was concluded that auditory radio interference degrades performance of this fine, continuous, open motor skill, and interference training appears to abate the effects of this degradation.
  •  

    1994

    M H Trimble; D M Koceja

    Modulation of the triceps surae H-reflex with training.

    Int. J. Neurosci. 76, 293 (1994)
    Indiana University School of Medicine, Department of Physical Therapy, Indianapolis 46202-5119.
    Thirteen neurologically healthy adults were asked to balance on a specially designed balance board. This board allowed rotation in the sagittal plane only. Muscle activity of the triceps surae and tibialis anterior was sampled at 2 kHz and recorded. When the subject was balanced, soleus H-reflexes were elicited in the right leg with a constant-current stimulus pulse. The peak to peak amplitude of the soleus H-reflex served as the perturbation to the subject's balance as well as the dependent variable in question. Subjects performed three blocks (7 H-reflexes/block) of standing control trials with the balance board supported, and seven blocks of balancing trials. Prior to each block, maximal M-waves were recorded to ensure electrode stability across blocks. Results indicated that the subjects were able to significantly reduce (p < .001) the gain the soleus H-reflex while balancing and after the balance training. As a group, the subjects decreased their peak to peak amplitude of the soleus H-reflex by 26.2 percent from the initial standing block to the last balancing block. Moreover, subjects were also able to significantly reduce the gain of their standing control H-reflexes, supporting the notion of longer-term adaptability of the spinal stretch reflex. It is concluded that the progressive reduction in the H-reflex gain with short-term training may represent functional adaptation in the central nervous system.
  •  

    1993

    D M Koceja; M H Trimble; D R Earles

    Inhibition of the soleus H-reflex in standing man.

    Brain Res. 629, 155 (1993)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    Thirteen neurologically healthy adults were asked to balance on a specially designed balance board. This board allowed rotation in the sagittal plane only. Muscle activity of the triceps surae and tibialis anterior was sampled at 2 kHz and recorded. When the subject was balanced, soleus H-reflexes were elicited in the right leg with a constant-current stimulus pulse. The peak to peak amplitude of the soleus H-reflex served as the perturbation to the subject's balance as well as the dependent variable in question. Subjects performed three blocks (7 H-reflexes/block) of standing control trials with the balance board supported, and seven blocks of balancing trials. Prior to each block, maximal M-waves were recorded to ensure electrode stability across blocks. Results indicated that the subjects were able to significantly reduce (p < .001) the gain the soleus H-reflex while balancing and after the balance training. As a group, the subjects decreased their peak to peak amplitude of the soleus H-reflex by 26.2 percent from the initial standing block to the last balancing block. Moreover, subjects were also able to significantly reduce the gain of their standing control H-reflexes, supporting the notion of longer-term adaptability of the spinal stretch reflex. It is concluded that the progressive reduction in the H-reflex gain with short-term training may represent functional adaptation in the central nervous system.
  •  

    1993

    J R Burke; D M Koceja; G Kamen

    The relationship between body height extremes and the conditioned patellar tendon reflex response.

    Int. J. Neurosci. 72, 45 (1993)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    The purpose of this study was to determine the effects of extreme body heights on the conditioned patellar tendon reflex response in an attempt to differentiate between the contributions of supraspinal and spinal mechanisms on long-latency reflex facilitation. Unilateral and conditioned right patellar tendon reflexes were assessed in 10 extremely short males and females and 10 extremely tall males and females. The conditioning stimulus was a contralateral patellar tendon tap and the conditioning intervals were 10, 15, 25, 50, 60, 75, 100, 150, and 300 ms. There was a long-latency facilitation of quadriceps excitability beginning at the 75 ms conditioning interval regardless of the height of the subject. It is hypothesized that the similar conditioned patellar tendon recovery profiles in the extremely short subjects and the extremely tall subjects reflects the activation of a spinal polysynaptic pathway as the predominant mechanism for our long-latency reflex facilitation.
  •  

    1993

    D M Koceja

    Influence of quadriceps conditioning on soleus motoneuron excitability in young and old adults.

    Med Sci Sports Exerc 25, 245 (1993)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    In an effort to investigate neuromuscular changes with age, the isometric force-time curve of the Achilles tendon-tap reflex (ATR) was measured in 10 college age (M = 20.9 yr) and 10 healthy active old subjects (M = 74.3 yr). In an effort to investigate spinal interneuronal pathways, the tendon-jerk was also conditioned with a tap to the ipsilateral or contralateral patellar tendon. The conditioning stimulus preceded the ATR by 25, 40, 55, 70, 85, 100, 115, 130, or 145 ms. Three trials were elicited at each conditioning interval plus three unilateral trials, for 30 trials per experimental session. Results indicated that the force production of the unilateral Achilles tendon-tap reflex was significantly reduced and the half-relaxation times were significantly lengthened in the old subjects. Moreover, ipsilateral conditioning produced short-latency facilitation and long-latency inhibition to the triceps surae in young subjects, whereas the same conditioning produced only a delayed long-latency inhibition in the old subjects. Similarly, the contralateral conditioning produced short-latency facilitation in the young subjects, with no changes observed in the old subjects. It is concluded that unilateral Achilles tendon-tap responses are different for the two groups, and that the reflex recovery profiles for the two groups are different. Several neurophysiological mechanisms are proposed to contribute to these differences.
  •  

    1992

    D M Koceja; G Kamen

    Contralateral influences on triceps surae motoneuron excitability.

    Electroencephalogr Clin Neurophysiol 85, 177 (1992)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time curve of the tibial nerve H-reflex in 12 college age subjects. We also conditioned the reflex with a contralateral H-reflex stimulus or a contralateral tendon-tap, to ascertain the effects of crossed spinal segmental inputs on alpha motoneuron excitability. The conditioning stimulus preceded the test reflex by 10, 25, 40, 55, 70, 85, 100, 115, 130 or 145 msec. The results demonstrate that a conditioning tibial nerve H-reflex produced marked facilitation onto the contralateral triceps surae motoneurons, predominantly at longer-latency intervals. Conversely, a conditioning Achilles tendon-tap produced long-latency inhibition to the triceps surae. These results demonstrate that differential motoneuron excitability changes can be produced by electrical and mechanical conditioning stimuli. Moreover, these excitability changes may be long lasting and only appear after a relatively long latency. Several neurophysiological mechanisms are proposed to contribute to these changes.
  •  

    1992

    D M Koceja; G Kamen

    Segmental reflex organization in endurance-trained athletes and untrained subjects.

    Med Sci Sports Exerc 24, 235 (1992)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    In an effort to investigate the effects of training on spinal reflex pathways in humans, we measured the isometric force-time curve of the patellar (PTR) and Achilles (ATR) tendon-tap reflex in 12 endurance-trained (ET) athletes and 12 control (C) subjects. We also conditioned the tendon jerk with a contralateral or ipsilateral tendon-tap stimulus, to ascertain the effects of segmental inputs on crossed-spinal reflex activity. The conditioning stimulus preceded the test reflex by 25, 40, 55, 70, 85, 100, 115, 130, or 145 ms. The results demonstrated significant differences in control reflexes and conditioned reflexes between the two groups. A contralateral patellar tendon-tap produced a significantly greater excitatory effect to the contralateral quadriceps motoneurons for the ET group, whereas a contra- or ipsilateral conditioning caused a significantly greater inhibitory effect to the triceps surae motoneurons for the ET athletes. These results demonstrate that motoneuron excitability changes can be produced as a result of ipsi- and contralateral segmental inputs, and raise the possibility that trained athletes demonstrate different reflex recovery profiles. Several neurophysiological mechanisms are proposed to contribute to these changes.
  •  

    1991

    D M Koceja; R H Bernacki; G Kamen

    Methodology for the quantitative assessment of human crossed-spinal reflex pathways.

    Med Biol Eng Comput 29, 603 (1991)
    Department of Kinesiology, Indiana University, Bloomington 47405.
     
  •  

    1991

    D M Koceja; J R Burke; G Kamen

    Organization of segmental reflexes in trained dancers.

    Int J Sports Med 12, 285 (1991)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    Unilateral and conditioned Achilles tendontap reflex (ATR) characteristics were examined in a group of skilled dancers and a group of sedentary, untrained subjects (n = 7/group). For the conditioned reflex, the right ATR was conditioned by a tap to the left Achilles tendon using intervals of 10, 40, 70, 100, 130, 160 and 190 ms. Peak isometric force, contraction time and half-relaxation time were examined on each trial. The results indicated that the trained dancers exhibited less unilateral isometric force and longer half-relaxation times (p less than 0.05) than the untrained subjects. Moreover, the contralateral conditioning stimulus caused a more marked short-latency facilitation as well as a long-latency inhibition in the reflex force characteristics for the trained dancers when compared with the untrained subjects. These differences in both simple and conditioned reflexes in individuals trained for dance activities may reflect differences in muscle stiffness, tissue compliance or neural organization.
  •  

    1991

    D M Koceja; G Kamen

    Interactions in human quadriceps-triceps surae motoneuron pathways.

    Exp Brain Res 86, 433 (1991)
    Department of Kinesiology, Indiana University, Bloomington 47405.
    In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time curve of the patellar (PTR) and Achilles (ATR) tendon-tap reflex in 12 college age subjects. We also conditioned the tendon jerk with a contralateral or ipsilateral tendon-tap stimulus, to ascertain the effects of segmental inputs on crossed-spinal reflex activity. The conditioning stimulus preceded the test reflex by 25, 40, 55, 70, 85, 100, 115, 130 or 145 ms. The results demonstrate that a tap to the contralateral patellar tendon produced long-latency excitation of quadriceps motoneurons, but a tap to the contralateral Achilles tendon produced short-latency facilitation and long-latency inhibition of the triceps surae motoneurons. Also, a conditioning tap to the contra- or ipsilateral patellar tendon produced a brief short-latency facilitation that was followed by a distinct, long-latency inhibition of triceps surae motoneurons. These results demonstrate that motoneuron excitability changes can be produced as a result of ispi- and contralateral segmental inputs. Moreover, these excitability changes may be long-lasting and only appear after a relatively long-latency. Several neurophysiological mechanisms are proposed to contribute to these changes.
  •  

    1990

    D M Koceja; G Kamen; J R Burke

    Quadriceps excitability is enhanced by a conditioning tap to the Achilles tendon.

    Electromyogr Clin Neurophysiol 30, 415 (1990)
    Motor Control Laboratory, Indiana University, Bloomington.
    In an effort to more fully investigate spinal reflex pathways in humans, we measured the isometric force-time characteristics of the patellar tendon-tap reflex in ten college-age subjects. We also conditioned the tendon jerk with a tap to the contralateral Achilles tendon or the ipsilateral Achilles tendon. The results clearly demonstrated that a conditioning tap to the Achilles tendon produced a marked (greater than 200 percent) excitatory effect onto the quadriceps muscle. Also, this effect occurred sooner when the quadriceps was conditioned by an ipsilateral stimulus rather than a contralateral stimulus. It is concluded that in accord with other conditioning studies to date, the quadriceps muscle is characterized by a predominantly excitatory effect caused by a conditioning stimulus, and that this arousal is independent of the origin of the conditioning stimulus.
  •  

    1989

    J R Burke; G Kamen; D M Koceja

    Long-latency enhancement of quadriceps excitability from stimulation of skin afferents in young and old adults.

    J Gerontol 44, (1989)
    Motor Control Laboratory, Indiana University.
    This study examined the role of cutaneous input on spinal excitability in young and old adults. Patellar tendon reflexes were elicited in 15 old adults (M = 75 yrs) and 25 young adults (M = 26 yrs) at intervals ranging from 15 to 175 ms following cutaneous stimulation to one of four skin sites: (a) ipsilateral calf, (b) contralateral calf (old adults only), (c) ipsilateral anterior thigh, and (d) contralateral anterior thigh. The younger adults had a more vigorous reflex response than the older adults, as indicated by peak force. Force latencies were also faster for the younger adults than the older adults. However, both age groups showed a long-latency facilitation of quadriceps excitability regardless of cutaneous stimulation site. Thus, it seems that low threshold cutaneous afferents contribute an excitatory input to the extensor motoneuron pool that is maintained with age.
  •  

    1989

    G Kamen; D M Koceja

    Contralateral influences on patellar tendon reflexes in young and old adults.

    Neurobiol. Aging 10, 311 (1989)
    Department of Physical Therapy, Boston University, MA 02215.
    In an effort to more fully investigate age-related changes in spinal reflex parameters, we measured force-time characteristics of the patellar tendon reflex in aged subjects and contrasted these with data obtained from college-age individuals. We also conditioned the tendon jerk with a tap to the contralateral tendon. The results showed a marked tendon reflex enhancement in the old group, consisting of greater overall reflex force produced by the quadriceps. In both groups, the contralateral conditioning stimulus produced a short-latency inhibition (at 25 msec) followed by a longer-latency facilitation (beginning at 75 msec). Both the early inhibition and the later reflex enhancement were greater in the aged subjects. We suggest that some age-related change may occur at the spinal level to compensate for decrements in more complex motor functioning.
  •  

    1988

    D M Koceja; G Kamen

    Conditioned patellar tendon reflexes in sprint- and endurance-trained athletes.

    Med Sci Sports Exerc 20, 172 (1988)
    Indiana University Motor Control Laboratory, Bloomington 47405.
    Tendon reflex characteristics were examined in endurance-trained, sprint-trained, and control subjects (10 SS/group) using a conditioned patellar tendon reflex (PTR) paradigm. Paired PTRs were administered using inter-tap intervals of 0, 25, 50, 75, 150, and 300 ms, with the left leg reflex elicited first, followed by a right leg PTR. A force transducer secured at the ankle was used to measure peak force, time to peak force, and reflex latency. In the unilateral condition, significant differences (P less than 0.05) existed between athletic groups, with the sprint-trained athletes exhibiting greater peak force, faster time to peak force, and faster reflex latency than the endurance athletes. Significant differences (P less than 0.05) also existed for the conditioned reflex. There was a slight depression in reflex parameters in the untrained and sprint-trained groups up to an interval of 50 ms. At later intervals (greater than 50 ms), a marked enhancement occurred in all groups for all dependent measures studied. This longer latency excitatory effect persisted until the 150 ms interval. These differences in both simple and conditioned reflexes in individuals trained for endurance and sprint activities may reflect inherent differences in muscle-tendon stiffness or neural organization.

 

 

 
 
 

 
 
 
 
 
 
 
 

David M. Koceja
David M. Koceja

 

 

 



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