The sensory control of movements has been shown to be impaired with Parkinson’s disease. I investigated the task, reach-to-eat, in which advancing of the limb towards a target is guided by vision and withdrawal of the grasped target to the mouth is guided by somatosensation (i.e., haptics and proprioception). Parkinson’s diseased subjects display an alteration in the balance of visual and proprioceptive guidance, such that they display increased visual fixation on the target prior to movement onset that persists following the grasp. Music therapy can normalize the balance between visual and proprioceptive guidance on the reach-to-eat task, as visual fixation with the target prior to movement onset is consistent with controls, and disengagement following grasp no longer differs from mild Parkinson’s disease subjects. These results are the first to demonstrate that music can have an ameliorating effect on the sensory impairments seen in the control of forelimb movements in Parkinson’s disease. / xiv, 147 leaves : ill. ; 29 cm. --

The neural and sensory mechanisms underlying appropriate muscle recruitment in response to balance challenges remains elusive. We asked whether the decerebrate cat preparation might be employed for further investigation of postural mechanisms. First, we evaluated the muscular activation patterns and three-dimensional whole limb forces generated by a modified premammillary decerebrated cat. We hypothesized that directionally appropriate muscle activation does not require the cerebral cortices. Furthermore, we hypothesized that the muscle responses would generate functionally appropriate and constrained force responses similar to those reported in the intact animal. Data confirmed both of our hypotheses and suggested important roles for the brainstem and spinal cord in mediating directionally appropriate muscular activation. Second, we investigated how individual muscle activation is translated to functional ground reaction forces. We hypothesized that muscles are selectively activated based upon their potential counteractive endpoint force. Data demonstrated that the endpoint force generated by each muscle through stimulation was directed oppositely to the principal direction of each muscle's EMG tuning curve. Further, muscles that have variable tuning curves were found to have variable endpoint forces in the XY plane. We further hypothesized that the biomechanical constraints of individual muscle actions generate the constrained ground reaction forces created in response to support surface perturbations. We found that there was a lack of muscles with strong medial-lateral actions in the XY plane. This was further exaggerated at long stance conditions, which corresponds to the increased force constraint present in the intact animal under the same conditions. Third, we investigated how loss of cutaneous feedback from the footpads affects the muscle recruitment in response to support surface perturbations. We utilized our decerebrate cat model as it allows 1) isolation of the proprioceptive system (cutaneous and muscle receptor) and 2) observation of the cutaneous loss before significant compensation by the animal. We hypothesized that muscle spindles drive directionally sensitive muscle activation during postural disturbances. Therefore, we expected that loss of cutaneous feedback from the foot soles would not alter the directional properties of muscle activation. While background activity was significantly diminished, the directionally sensitive muscular activation remained intact. Due to fixation of the head, the decerebrate cat additionally does not have access to vestibular or visual inputs. Therefore, this result strongly implicates muscle receptors as the primary source of directional feedback. Finally to confirm that muscle receptors, specifically muscle spindles, are capable of generating feedback to drive the directionally tuning, we investigated the response properties of muscle spindles to horizontal support surface perturbations in the anesthetized cat. As previously stated, we hypothesized that muscle spindles provide the feedback necessary for properly directed muscular responses. We further hypothesized that muscle spindles can relay feedback about the perturbation parameters such as velocity and the initial stance condtion. Results confirmed that muscle spindle generate activation patterns remarkably similar to muscular activation patterns generated in the intact cat. This information, along the knowledge that cutaneous feedback does not substantially eliminate directional tuning, strongly suggests that muscle spindles contribute the critical directional feedback to drive muscular activation in response to support surface perturbations.

Thesis (MScSportSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Postural deformities are a commonly encountered problem among children. Most of the aches and pains of adults are the result, not of injuries, but of the long-term effects of distortions in posture or alignment that have their origins in childhood or adolescence. Television, video entertainment, motorized transportation, fast food and lack of regular physical activity contribute to the poor physical condition of children. School screening for scoliosis is mandated in schools in 26 states of the United States (US) for children between 10 and 16 years of age. Previous studies conducted in the US found that 160 out of 1000 people suffer from scoliosis. This means that scoliosis is as prevalent as hypertension or diabetes mellitus (Boachie-Adjei & Lonner, 1996). Identification of postural deformities at an early stage makes early treatment possible, which may, in future, prevent serious postural abnormalities. The American Academy of Orthopedic Surgeons approved the implementation of screening programs in schools in 1974 (Lonstein, 1988). Few studies have included the entire musculoskeletal system. The purpose of this study was to determine the prevalence of postural deformities among children aged 11 to 13 years in selected primary schools in the Western Cape. The study also proposes to investigate factors that may influence the prevalence rate of postural deformities. These factors included age, gender, school district, weight, height, BMI (Body Mass Index), fat%, waist-hip ratio, and physical activity. Letters were sent to 15 primary schools within a 30km radius of Stellenbosch. This region included Stellenbosch, Strand, and Kuilsrivier. Four schools replied, giving permission to conduct the study at their schools. The sample (N=288, mean age=12.36, SD=0.92) consisted of 78 scholars from grade five; 104 scholars form grade six; and 106 scholars from grade seven. Of the total number of scholars examined (288), 154 were boys, and 134 were girls. Only children with parental consent were allowed to participate in the study. Anthropometric measures included stature, mass, skinfoids (two-site skinfoid), waist- and hip circumferences and trochanterion leg length. Level of physical activity and family history of deformities were obtained by means of a questionnaire. The New York Posture Test was used for postural evaluation (Bloomfield et aI., 1994:320; Reedeo Inc., 2001. This Posture Test was designed for the screening of 13 categories of deformities. Using a "see-through" posture grid, lateral and posterior examinations were performed. The "Adam's position" (forward bending) was used for further scoliosis evaluation. Quantitative data was analyzed, using Statistica (Statsoft, 2001) and classification tree methodology (Breiman et aI., 1993). The anthropometric results indicated that the subjects had a mean stature of 1.54m, mass of 47.48kg, BMI of 19.75, waist-hip ratio of 0.79 and fat% (Lohman, 1987) of 21.35%. The prevalence of postural deformities was as follows: Lordosis, 70%; Kyphosis, 57%; Uneven shoulders, 55%; Inclined trunk, 43%; Winged scapulae, 42%; Pronated feet, 30%; Flat feet, 30%; Flat chest, 29%; Forward head, 28%; Protruding abdomen, 28%; Uneven hips, 11%; Scoliosis, 10%; and Twisted head, 1%. Uneven hips, scoliosis and twisted head were not considered for statistical purposes, because of their low incidence compared to the other deformities. The factors that influenced the prevalence rate of deformities the most were BMI and fat%. A higher BMI and fat% resulted in a higher prevalence rate in most deformities. The prevalence rate of postural deformities in this study was considerably high. Sedentary lifestyles of children (watching television, computer games, junk food and physical inactivity) were a contributing factor in the high prevalence rate of postural deformities. It is known that overweight and sedentary behavior of children is increasing and this could pose an alarming concern to the health of a child. Also, if a significant correlation does exist between the prevalence of postural deformities and conditions such as back pain, the high prevalence rate reported in this study is a matter of concern. / AFRIKAANSE OPSOMMING: Postuurafwykings is "n algemene probleem wat dikwels onder kinders voorkom. Baie van die skete en pyne by volwassenes spruit nie uit beserings nie, maar vanuit langtermyn gevolge van swak postuur wat huloorsprong uit die kinderjare het. Televisie, videospeletjies, vervoer per motor, kitskos en gebrek aan fisieke aktiwiteit dra by tot die swak fisieke kondisie van kinders. Evalueringsprogramme in skole word in 26 state in die Verenigde State van Amerika (VSA) toegepas vir kinders tussen die ouderdomme van 10 en 16 jaar. Vorige studies in die VSA het getoon dat 160 uit 1000 mense skoliose het (Boachie-Adjei & Lonner, 1996). Dit beteken dat skoliose net so veel voorkom soos hipertensie of diabetes mellitus. Identifikasie van postuurafwykings op "n vroeë stadium maak vroeë behandeling moontlik, wat in die toekoms ernstige postuurafwykings kan voorkom. Die "American Academy of Orthopedie Surgeons" het reeds in 1974 die implementering van assesseringsprogramme goedgekeur (Lonstein, 1988). Volgens navorsing het slegs "n beperkte aantal studies die hele spierskeletale stelsel geëvalueer. Die doel van hierdie studie was om die voorkoms van postuurafwykings by kinders tussen die ouderdomme van 11 en 13 jaar in geselekteerde Wes-Kaapse skole te bepaal. Die studie het ook faktore wat "n invloed op die voorkoms van postuurafwykings kan hê, ingesluit. Hierdie faktore het onder andere ouderdom, geslag, skool, gewig, lengte, LMI (Liggaamsmassa-indeks), vet%, middel-heup-ratio en fisieke aktiwiteit ingesluit. Uitnodigingsbriewe is na 15 laerskole binne "n 30km radius vanaf Stellenbosch gestuur. Dit het ingesluit Stellenbosch, Strand, en Kuilsrivier. Vier skole het toestemming verleen om die studie by die betrokke skole te loods. Die steekproef (N=288, gemiddelde ouderdom = 12.36, SD=0.92) het bestaan uit 78 leerlinge uit graad vyf; 104 leerlinge uit graad ses en 106 leerlinge uit graad sewe. Uit die totale aantal leerlinge wat geëvalueer is, was daar 154 seuns en 134 dogters. Antropometriese metings het die volgende ingesluit: lengte, gewig, velvoue (twee-velvou meting), middel- en heupomtrekke en trochanterion beenlengte. Fisieke aktiwiteitsvlak en familiegeskiedenis van postuurafwykings is bepaal met behulp van "n vraelys. Die "New York Posture Tesf' is gebruik vir postuurevaluasie (Bloomfield et al., 1994:320; Reedco Inc., 2001). Hierdie toets is ontwerp vir die evaluering van 13 deformiteite. Die kinders is vanuit 'n posterior en anterior aansig ge-evalueer met behulp van 'n "deurskynende" postuurruitnet (grid). Die "Adam's-" toets (vooroorbuig-toets) is gebruik vir verdere evaluering van skoliose. Statistica (StatSoft, 2001) en klassifikasieboom-metodologie (Breiman et al., 1993) is gebruik vir statistiese ontleding. Die proefpersone het 'n gemiddelde lengte van 1.54m, gewig van 47.48kg, LMI van 19.75, middel-heup-ratio van 0.79 en vet% (Lohman, 1987) van 21.35% gehad. Die voorkoms van die onderskeie postuurafwykings was as volg: Lordose,70%; Kifose, 57%; Ongelyke skouers, 55%; Romp na posterior gebuig, 43%; Gevleuelde skapulas, 42%; Voetpronasie, 30%; Plat voete, 30%; Plat bors, 29%; Protraksie: skedel, 28%; Uitstaan buik, 28%; Ongelyke heupe, 11%; Skoliose, 10%; en Gekantelde hoof, 1%. Ongelyke heupe, skoliose en gekantelde hoof het minder voorgekom in vergelyking met die ander deformiteite, daarom is die deformiteite nie vir statistiese analise in aammerking gebring nie. LMI en vet% was die faktore wat die voorkoms van postuurafwykings die meeste beïnvloed het. 'n Hoër LMI en vet% het 'n toenemende voorkoms in meeste deformiteite veroorsaak. Die voorkoms van postuurafwyking in hierdie studie was hoog. Sedentêre leefwyses van kinders (TV, rekenaarspeletjies, gemorskos, en fisieke onaktiwiteit) het bygedra tot die hoë voorkoms. Die voorkoms van oorgewig en sedentêre leefwyses is besig om te verhoog by kinders en kan ernstige gevolge vir die gesondheid van die kind inhou. Indien daar 'n betekenisvolle korrelasie tussen die voorkoms van postuurafwykings en kondisies soos rugpyn is, dan blyk die hoë voorkoms, wat in hierdie studie gevind is, 'n bron van bekommernis te wees. Postuurevalueringsprogramme is 'n effektiewe metode vir die vroeë identifikasie van postuurafwykings, aangesien dit vroeë identifikasie en konserwatiewe behandeling moontlik maak.

M. Tech. Electrical Engineering. / Investigates a new approach of wheelchair control, based on the user behaviour recognition. This objective involves two steps in the resolution of the problem. The first step is to determine the action the user initiates. Therefore, the present study will mostly refer to literatures on car driver behaviour modelling, as several studies have been conducted in that domain. The proposed model of user's behaviour presented here is based on probabilistic graphical model, for instance, Bayesian network. The second step is the generation of an assistive control signal that will compensate the user input, depending on the driving task inferred by the Bayesian network.Experiments have been conducted on a virtual environment model developed in Matlab and several users participated to the experiments. The results show a great potential of Bayesian Network model to infer on human behaviour and also a satisfying output from the ANFIS model as it delivers signals following the user's behaviour.

The effect of concurrent music on gait was investigated amongst Parkinson‟s disease (PD) patients and age-matched control subjects. Ten people (mean age 66.6 ± 6.5 years) with idiopathic Parkinson‟s disease and ten healthy age-matched (mean age 65.4 ± 6.3 years) control subjects completed steady state gait, dual task and obstacle negotiation trials in two differing test conditions; no music and whilst listening to music. Testing conditions were counterbalanced between subjects. The gait performance of PD patients was detrimentally affected by concurrently listening to music during steady state gait and obstacle negotiation, an effect that was further compounded in the dual task context. These findings imply that listening to music concurrent to gait may increase the attentional cost for PD patients. The findings of these studies have implications for patients, who may be at greater risk of falls in multi-task situations. / xi, 113 leaves ; 29 cm. --

Falls are a common problem among older adults, including those who are relatively healthy and living independently. Exercise has been recommended as an intervention to reduce falls by slowing and/or reversing age-related declines in balance, strength, and mobility. However, it remains unclear which types or combinations of programs are most effective. The objective of this study was to investigate whether exercise programs performed by healthy older adults were associated with superior balance, strength, and functional mobility measures that are pertinent to fall prevention. This study compared three distinct groups: participants of a balance- and strength-focused training program (i.e., Better Bones and Balance®), participants engaged in a general walking program, and sedentary individuals. Balance was measured using the Sensory Organization Test composite score and sensory ratios. Isometric strength of the lateral hip stabilizers (i.e., abductors and adductors) was measured in terms of maximum voluntary contraction and rapid torque production. Rapid torque measures included contractile impulse and rate of torque development evaluated at 0-100 ms and 0-300 ms from contraction onset. Functional mobility was measured by the time to complete the Four Square Step Test. Hip abduction contractile impulse (0-300 ms) was 1.905 Nm*s and 1.539 Nm*s higher for the Better Bones and Balance (BBB) group compared to the walking and sedentary groups, respectively. No differences were found among the groups for any of the hip adduction torque measures or Sensory Organization Test balance scores. The BBB group completed the Four Square Step Test faster than the walking and sedentary groups by 0.90 s and 1.06 s, respectively. In conclusion, participation in the balance- and strength-focused training program was associated with superior performance in some measures of strength and functional mobility that may be important for fall prevention. / Graduation date: 2013