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Chow J.W.,Center for Neuroscience and Neurological Recovery | Knudson D.V.,Texas State University
Sports Biomechanics | Year: 2011

A deterministic model is a modeling paradigm that determines the relationships between a movement outcome measure and the biomechanical factors that produce such a measure. This review provides an overview of the use of deterministic models in biomechanics research, a historical summary of this research, and an analysis of the advantages and disadvantages of using deterministic models. The deterministic model approach has been utilized in technique analysis over the last three decades, especially in swimming, athletics field events, and gymnastics. In addition to their applications in sports and exercise biomechanics, deterministic models have been applied successfully in research on selected motor skills. The advantage of the deterministic model approach is that it helps to avoid selecting performance or injury variables arbitrarily and to provide the necessary theoretical basis for examining the relative importance of various factors that influence the outcome of a movement task. Several disadvantages of deterministic models, such as the use of subjective measures for the performance outcome, were discussed. It is recommended that exercise and sports biomechanics scholars should consider using deterministic models to help identify meaningful dependent variables in their studies. © 2011 Taylor & Francis.


Sung P.S.,Korea University | Yoon B.,Korea University | Lee D.C.,Center for Neuroscience and Neurological Recovery
Spine | Year: 2010

Study Design: An experimental design comparing kinematic changes in the lumbar spine axis in subjects with and without low back pain (LBP) while standing on one leg with and without visual feedback. Objective: The purpose of this study was to evaluate the lumbar stability index, which includes re ative holding time (RHT) and relative standstill time (RST), in subjects with and without LBP. Summary of Background Data: Even though a number of studies have evaluated postural adjustments based on kinematic changes in subjects with LBP, lumbar spine stability has not been examined for abnormal postural responses with visual feedback. Methods: All participants were asked to maintain the stork test position (standing on one leg with the contra lateral hip flexed 90°) for 25 seconds. The outcome measures included RHT and RST for the axes of the core spine and lumbar spine. Independent t tests were used to compare the differences between groups. Two-way repeated measure analysis of variance was used to compare the differences for both axes. The age variable was used as a covariate to control confounding effects for the data analyses. Results: The RHT was longer for the lumbar spine axis in subjects without LBP than those with LBP, especially without visual feedback. There was also significant interaction in RST between subjects with and without LBP (F = 7.18, P = 0.01). For the core axis of the trunk, significant differences existed based on the main effect of side (F = 9.07, P = 0.004), trunk rotation (F = 24.30, P = 0.001), and both of these interactions (F = 8.93, P = 0.004). However, there was a lack of significant interaction with age for the lumbar and core spine axes (F = 0.06, P = 0.81). Conclusion: Although the control group included slightly younger volunteers compared with the LBP group, the stability index of the core spine significantly decreased in RHT and RST, especially when visual feedback was blocked for subjects with LBP. The interaction between visual feedback and trunk rotation indicated that core spine stability is critical in coordinating balance control. A trunk muscle imbalance may contribute to unbalanced postural activity, which could prompt a decreased, uncoordinated bracing effect in subjects with LBP. As a result, core spine training could be used in the prevention of postural instability in such subjects. © 2010, Lippincott Williams & Wilkins.


Gontkovsky S.T.,Center for Neuroscience and Neurological Recovery
Aging, Neuropsychology, and Cognition | Year: 2014

The Mini-Mental State Examination (MMSE) and Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) were administered to 46 outpatients diagnosed with multiple sclerosis (MS). MMSE total raw score was significantly and positively correlated with all WAIS-IV indexes, even when controlling for the effects of participant educational level, with the strongest relationship being with Full Scale IQ. These results suggest that clinicians consider patient intellectual functioning, in particular Full Scale IQ, when diagnosing neurocognitive impairment based on screening with the MMSE in individuals with MS. © 2014 © Taylor & Francis.


Gontkovsky S.T.,Center for Neuroscience and Neurological Recovery
Brain Injury | Year: 2011

Study design: Case report. Background: Systemic sclerosis is a rare and chronic autoimmune disease of the body's connective tissue that historically has not been associated with primary involvement of the central nervous system. Objective: To describe the neuropsychological sequelae of systemic sclerosis in a 56-year-old male. Results: Neurocognitive deficits were demonstrated by the patient on select components of memory and language as well as across measures of executive functioning. Significant depression and reduced self-concept were also identified. Discussion: Neuropsychological dysfunction in patients with systemic sclerosis has largely been ignored in the clinical setting. Identification of neurocognitive impairment and emotional stress can facilitate interventions that consequently may increase adherence with medical treatment and increase quality-of-life. © 2011 Informa UK Ltd All rights reserved.


Chow J.W.,Center for Neuroscience and Neurological Recovery | Stokic D.S.,Center for Neuroscience and Neurological Recovery
Journal of Applied Physiology | Year: 2011

We tested the hypothesis that force variability and error during maintenance of submaximal isometric knee extension are greater in subacute stroke patients than in controls and are related to motor impairments. Contralesional (more-affected) and ipsilesional (less-affected) legs of 33 stroke patients with sufficiently high motor abilities (62 ± 13 yr, 16 ± 2 days postinjury) and the dominant leg of 20 controls (62 ± 10 yr) were tested in sitting position. After peak knee extension torque [maximum voluntary contraction (MVC)] was established, subjects maintained 10, 20, 30, and 50% of MVC as steady and accurate as possible for 10 s by matching voluntary force to the target level displayed on a monitor. Coefficient of variation (CV) and root-meansquare error (RMSE) were used to quantify force variability and error, respectively. The MVC was significantly smaller in the more-affected than less-affected leg, and both were significantly lower than in controls. The CV was significantly larger in the more-affected than less-affected leg at 20 and 50% MVC, whereas both were significantly larger compared with controls across all force levels. Both moreaffected and less-affected legs of patients showed significantly greater RMSE than controls at 30 and 50% MVC. The CV and RMSE were not related to the Fugl-Meyer motor score or to the Rivermead Mobility Index. The CV negatively correlated with MVC in controls but only in the less-affected leg of patients. It is concluded that isometric knee extension strength and force control are bilaterally impaired soon after stroke but more so in the more-affected leg. Future studies should examine possible mechanisms and the evolution of these changes. Copyright © 2011 the American Physiological Society.


Chow J.W.,Center for Neuroscience and Neurological Recovery | Yablon S.A.,Center for Neuroscience and Neurological Recovery | Yablon S.A.,University of Alberta | Stokic D.S.,Center for Neuroscience and Neurological Recovery
Clinical Neurophysiology | Year: 2012

Objective: Examine (1) coactivation between tibialis anterior (TA) and medial gastrocnemius (MG) muscles during stance phase of gait in patients with moderate-to-severe resting hypertonia after stroke or traumatic brain injury (TBI) and (2) the relationship between coactivation and stretch velocity-dependent increase in MG activity. Methods: Gait and surface EMG were recorded from patients with stroke or TBI (11 each) and corresponding healthy controls (n= 11) to determine the magnitude and duration of TA-MG coactivation. The frequency and gain of positive (>0) and significant positive (p< 0.05) EMG-lengthening velocity (EMG-LV) slope in MG were related to coactivation parameters. Results: The magnitude of coactivation was increased on the more-affected (MA) side, whereas the duration was prolonged on the less-affected (LA) side of both stroke and TBI patients. The difference reached significance during the initial and late double support. The magnitude of coactivation positively correlated with the gain of significant positive EMG-LV slope in TBI patients. Conclusions: Increased coactivation between TA and MG during initial and late double support is a unique feature of gait in stroke and TBI patients with muscle hypertonia. Significance: Increased coactivation may represent an adaptation to compensate for impaired stability during step transition after stroke and TBI. © 2012 International Federation of Clinical Neurophysiology.


Chow J.W.,Center for Neuroscience and Neurological Recovery | Stokic D.S.,Center for Neuroscience and Neurological Recovery
Experimental Brain Research | Year: 2014

We compared gait using the planar law of intersegmental coordination between 14 hemorrhagic stroke subjects walking at a self-selected normal speed (56 ± 21 cm/s) and 15 age-matched healthy controls walking at a very slow speed (56 ± 19 cm/s). Sagittal plane elevation angles of the thigh, shank, and foot segments were submitted to principal component analysis. Additional outcome measures included the range of elevation angle and timing of peak elevation angle of the thigh, shank, and foot segments. The range of elevation angles at the shank and foot was significantly smaller in the paretic leg than non-paretic and control legs. Also, the peak elevation angle at the thigh occurred significantly later in the gait cycle in the paretic than control leg. Gait of both stroke and control subjects followed the planar law with the first two principal components explaining approximately 99 % of the variance. However, the three-dimensional trajectory of elevation angles (gait loop) in stroke subjects deviated from the typical teardrop shape bilaterally, which was more exaggerated in the paretic leg. Compared to the non-paretic and control legs, the paretic leg showed significantly increased absolute loading of the thigh elevation angle and decreased absolute loadings of the shank and foot elevation angles on the first principal component, whereas the opposite was observed for the second principal component. Despite following the planar law, the gait of chronic stroke subjects is characterized by atypical timing of the thigh motion and disrupted intersegmental coordination of both legs. © 2014, Springer-Verlag Berlin Heidelberg.


Chow J.W.,Center for Neuroscience and Neurological Recovery | Stokic D.S.,Center for Neuroscience and Neurological Recovery
Neuroscience | Year: 2014

We examined changes in the variability, frequency composition, and complexity of force signal from subacute to chronic stage of stroke during maintenance of isometric knee extension and compared these parameters between chronic stroke and healthy subjects. The sample included 15 healthy (65 ± 8. years) and 23 chronic stroke subjects (65 ± 14. years, 6-112. months post-stroke) of whom 10 (64 ± 15. years) were also examined 11-22. days post-stroke (subacute stage). The subjects performed isometric knee extension at 10%, 20%, 30%, and 50% of peak torque for 10. s (two trials each). Coefficient of variation (CV) was used as a measure of force variability. The median frequency and relative power in the 0-3, 4-6, and 8-12. Hz bands were obtained through a power spectrum analysis of the force signal. The signal complexity was quantified using the sample entropy (SampEn). The longitudinal analysis revealed a significant decrease in CV from subacute to chronic stage across all contraction levels (P<. 0.001) but no significant changes in the frequency and entropy parameters. Comparison between the chronic stroke and control subjects revealed no significant difference in CV across the force levels (P > 0.05) but significantly decreased median frequency (P<. 0.01), with the relative power increased in 0-3. Hz band and decreased in 4-6 and 8-12. Hz bands in both paretic and non-paretic legs (P<. 0.001). SampEn was also significantly decreased in chronic stroke, bilaterally (P<. 0.001). These results indicate a shift toward lower frequencies and a less complex physiological process underlying force control in chronic stroke. The overall results suggest the improvement in force variability from subacute to chronic stroke but without normalization in the frequency composition and complexity of the force signal. Thus, disordered structure of the force signal remains a marker of impaired motor control long after stroke occurrence despite apparent recovery in force variability. © 2014 IBRO.


Nevels R.M.,Jackson State University | Dehon E.E.,Jackson State University | Alexander K.,Jackson State University | Gontkovsky S.T.,Center for Neuroscience and Neurological Recovery
Experimental and Clinical Psychopharmacology | Year: 2010

Research examining the role of pharmacological therapy in the treatment of children and adolescents with clinical disorders is growing. Clinical disorders that present with comorbid aggression can add a challenge to treatment. Child and adolescent neuropsychiatric disorders associated with aggression include attention-deficit hyperactivity disorder, various mood disorders and in particular bipolar disorders/pediatric mania, schizophrenia, mental retardation, oppositional defiant disorder, conduct disorder, and autism spectrum disorders. This review describes the psychopharmacy to treat these disorders and the aggression that often appears comorbidly. Existing literature regarding the efficacy and safety of psychotropics for youth with neuropsychiatric disorders also is discussed. In addition, general guidelines for psychopharmacy of aggression in children and adolescents are presented. Studies reviewed in this article provide evidence for the use of psychostimulants, alpha-2 agonists, beta blockers, lithium, anticonvulsant mood-stabilizers, atypical antipsychotics, traditional antipsychotics, and selective serotonin reuptake inhibitors in treating pediatric aggression with the choice of medication dependent on symptomology. Despite increased support for pediatric psychotropic use, there is a need for more long-term safety and efficacy studies of existing medications and newer, safer, and more effective agents with fewer side effects for the pharmacological treatment of all childhood disorders in which aggression is prominent. © 2010 American Psychological Association.


Leis A.A.,Center for Neuroscience and Neurological Recovery | Stokic D.S.,Center for Neuroscience and Neurological Recovery
Frontiers in Neurology | Year: 2012

The most common neuromuscular manifestation of West Nile virus (WNV) infection is a poliomyelitis syndrome with asymmetric paralysis variably involving one (monoparesis) to four limbs (quadriparesis), with or without brainstem involvement and respiratory failure. This syndrome of acute flaccid paralysis may occur without overt fever or meningoen-cephalitis. Although involvement of anterior horn cells in the spinal cord and motor neurons in the brainstem are the major sites of pathology responsible for neuromuscular signs, inflammation also may involve skeletal or cardiac muscle (myositis, myocarditis), motor axons (polyradiculitis), and peripheral nerves [Guillain-Barre syndrome (GBS), brachial plex-opathy]. In addition, involvement of spinal sympathetic neurons and ganglia provides an explanation for autonomic instability seen in some patients. Many patients also experience prolonged subjective generalized weakness and disabling fatigue. Despite recent evidence that WNV may persist long-term in the central nervous system or periphery in animals, the evidence in humans is controversial. WNV persistence would be of great concern in immunosuppressed patients or in those with prolonged or recurrent symptoms. Support for the contention thatWNV can lead to autoimmune disease arises from reports of patients presenting with various neuromuscular diseases that presumably involve autoimmune mechanisms (GBS, other demyelinating neuropathies, myasthenia gravis, brachial plexopathies, stiff-person syndrome, and delayed or recurrent symptoms). Although there is no specific treatment or vaccine currently approved in humans, and the standard remains supportive care, drugs that can alter the cascade of immunobiochemical events leading to neuronal death may be potentially useful (high-dose corticosteroids, interferon preparations, and intravenous immune globulin containing WNV-specific antibodies). Human experience with these agents seems promising based on anecdotal reports. © 2012 Leis and Stokic.

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