Thesis (M.S.)--Oregon State University, 2005. / Includes bibliographical references.

Orientador: Gil Lucio Almeida / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-08T18:24:05Z (GMT). No. of bitstreams: 1 Carvalho_RegianeLuz_D.pdf: 2608751 bytes, checksum: ce9d54702e5b3dae42169737d4eb3c81 (MD5) Previous issue date: 2006 / Resumo: O objetivo deste estudo foi investigar o papel e a integração das informações sensoriais em indivíduos neurologicamente normais e portadores da síndrome de Down durante a manutenção do equilíbrio em condição de grande instabilidade. Métodos: Participaram deste estudo 8 sujeitos portadores da síndrome de Down (SD) pareados por sexo e idade com o grupo controle que balançaram em uma gangorra de 60cm de raio com combinação de 3 alturas (7,12 e 17cm). As informações sensoriais foram manipuladas pela oclusão da visão, aplicação da estimulação galvânica nos processos mastóideos e vibração no tendão de Aquiles. Os ângulos das articulações do quadril, joelho e tornozelo e a atividade eletromiográfica de alguns músculos da perna e do tronco foram registrados. Resultados: Na ausência de manipulação sensorial os dois grupos analisados mantiveram o equilíbrio na gangorra utilizando principalmente o deslocamento e contração dos músculos do tornozelo. Os indivíduos controle adotaram um padrão alternado de ativação muscular, sendo que a magnitude da resposta postural foi modulada com a altura da gangorra. Em contrapartida os indivíduos portadores da SD apresentaram um padrão generalizado de cocontração e não foram de capazes de modular sua resposta com a demanda mecânica da tarefa. No grupo controle a estimulação galvânica reduziu a magnitude da resposta muscular, mas não alterou o padrão alternado de contração. Já a vibração alterou este padrão de ativação, tornando-o de certa forma semelhante ao observado nos indivíduos portadores da SD. Nos indivíduos portadores da SD a estimulação galvânica reduziu significantemente a habilidade de manutenção do equilíbrio na gangorra, ao passo que a vibração não alterou nem o equilíbrio nem a estratégia postural. Discussão. Os indivíduos controle se adaptaram a redução de uma modalidade sensorial. A perda da modulação do padrão alternado com a vibração indicou a grande importância da propriocepção na elaboração de respostas coordenadas ao nível do tornozelo. Por outro lado, os indivíduos portadores da SD apresentaram déficits na elaboração das respostas posturais. A perda do equilíbrio com a estimulação galvânica e a falta de efeito da vibração nos permite sugerir que, devido a déficits proprioceptivos a importância destas informações é reduzida acarretando em um aumento da importância das informações vestibulares durante o balanço na gangorra / Abstract: Introduction: The main of this study was investigates the sensory integration and function in neurological (CG) and Down syndrome (DS) subjects during balance on unstable seesaw. Methods: Eight individuals with DS and eight CG were studied. Six balancing conditions were collected combining 3 seesaw heights and two manipulations: Galvanic Vestibular Stimulation (GVS) and Achilles tendon vibration. The angles and EMG activities of the some leg and trunk muscles were collected. Results: The CG adopted an alternated pattern of ankle muscle activation during balance and modulated the balance with the seesaw height. The individuals with DS showed the co-contraction muscle pattern during balance and were not able to modulate the muscle answer with the seesaw height. The GVS did not affect CG pattern of muscle contraction although the muscle activation has been partially inhibit. However the detriment of reciprocal pattern was observed due to vibration and under this perceptual condition the control subjects adopted a muscle pattern that remember the ones used by individuals with DS. On the other hand, individuals with DS lack the ability to keep balance during the vestibular manipulation and were no affected by vibration. Discussion: The CNS of CG rapidly assess and re-weigh available sensory inputs, assuring the balance success. On the other hand, individuals with DS showed a deficit in the mechanism responsible to elicit an appropriate postural response. They increased the postural response with GVS and decreased with vibration. This fact may indicate that because of proprioceptive dysfunctions the individuals with DS re-weigh the organization of sensory systems increasing the importance of vestibular system and decreasing the proprioceptive importance / Doutorado / Fisiologia / Mestre em Biologia Funcional e Molecular

This study examined: the features and extent of the gait velocity decrement following stroke; the nature of the balance disorder and; investigated relationships between gait and balance. Twenty, fully-ambulant, hemiplegic subjects (12 men and 8 women), with a mean age of 57.2 years (± 10.7), were compared with 20 age- and sex-matched controls. Spatiotemporal gait kinematics were measured at five walking speeds ranging from "very slow" to "very fast". Balance was then measured while subjects maintained a variety of weight shift postures both with feet parallel and then in diagonal positions similar to those assumed during the double support phases of gait. Location and variability of centre of pressure (CP) were measured and the ranges over which CP could be shifted were calculated. Stroke subjects walked very slowly with their "fastest" walking speed (0.5 stat/s ± 0.23) no different from the "slowest" speed (0.38 stat/s ± 0.11) of the controls (p > 0.05). Differences between the other parameters were also found, many of which could be attributed to the differences in walking speeds. However, where the subjects walked at similar velocities, the hemiplegic sample walked with quicker and shoner strides suggesting a "cautious" gait pattern. The single support asymmetry of the strokes decreased with increasing walking speed. The positions of CP in the hemiplegic sample were found to be significantly displaced towards the unaffected leg and deficiencies were found in posterior shifts (p < 0.05). Postural sway was significantly greater in the hemiplegic sample implying less stable balance and the ranges over which the hemiplegic sample shifted weight were significantly less than the controls. The diagonal weight shift tests revealed the difficulty the stroke subjects experienced in shifting CP posterolaterally over the affected leg. Significant correlations were detected confmning the presence of relationships between static balance performance and gait. However, these correlation findings left considerable percentages of variance unexplained. These findings suggest that future rehabilitation should address the poverty of range of walking speed possessed by hemiplegic subjects as well as the reduced ability to weight shift over the hemiplegic limb, particularly posterolaterally. Further study to test these proposals is indicated.

Traumatic brain injury (TBI) is a prevalent condition worldwide with 1.7 million incidences in the U.S. alone. A range of clinical outcomes have been reported post TBI, including dementia, memory loss, and impaired balance and coordination. The lack FDA approved treatments for TBI drives the need for improved prevention and therapeutic strategies. Finite element (FE) models of brain injury mechanics can be used to advance these efforts. These computational models require appropriate constitutive properties in order to predict accurate brain tissue response to injury loading. Suitable experimental models need to be implemented to match the resolution and computational power of FE models. The first aim of this thesis was to characterize the mechanical properties of brain tissue. Here, human, porcine, and rat brain tissue mechanical responses to multistep indentation of increasing strains up to 30% strain were recorded. We tested whether the quasilinear theory of viscoelasticity (QLV) was required to capture the mechanical behavior of brain tissue, but observed that linear viscoelasticity was sufficient under the loading condition applied. Using this fitting model, brain tissue stiffness was found to be dependent on anatomical region, loading direction, age, sex and species to varying degrees. This analysis elucidated factors that affect brain tissue injury mechanics and can be used to improve the accuracy of FE models of brain tissue deformation to predict a biofidelic response to TBI. There is growing evidence linking TBI to pathologies leading to increased risk of neurodegeneration, like tauopathies. However better understanding of these underlying mechanisms is still needed. In our study, we utilized a custom shock tube design to induce blast TBI (bTBI). To isolate the effect of bTBI-induced tau pathology, tau was extracted from sham and shockwave exposed mice 24 hours post injury, referred to as sham and blast tau respectively. We showed that bTBI increased phosphorylation of tau and its propensity to oligomerize. Treatment with blast tau resulted in impaired behavior in mice as well as reduced long term potentiation (LTP) in acute hippocampal slices. Treatment with brain isolate from shockwave exposed tau knockout mice did not exhibit altered behavior or LTP response, eliminating the possibility that any confounding factor in the blast tau preparation was responsible for the impaired outcome. Administration of de-oligomerized blast tau prevented these cognitive impairments, suggesting that toxic effect of blast tau was attributed to its oligomeric form. Here we showed that blast injury can initiate cascades in tau pathology and exposure to this progression results in worsened neurological outcome. Tau phosphorylation is mainly regulated by protein phosphatase 2A (PP2A), whose activity can be altered by leucine carboxyl methyltransferase 1 (LCMT-1) and protein phosphatase methylesterase 1 (PME-1). We sought to leverage this mechanism by infusing LCMT-1 and PME-1 transgenic mice with sham and blast tau. LCMT-1 overexpression prevented behavior and LTP deficits induced by oligomeric blast tau. Furthermore, PME-1 overexpression worsened behavior and LTP response at subthreshold doses of oligomeric blast tau. Together, this illustrated the ability of these two enzymes to regulate the response to exposure of bTBI-induced pathogenic forms of tau. This study indicates the potential of targeting PP2A activity as a viable strategy for therapeutic intervention. In conclusion, this research expands our understanding of the complexity of brain tissue injury mechanics to inform computational models of TBI, illustrates the deleterious effect of pathogenic forms of tau induced by blast injury on cognitive function, and presents a potential target mechanism for the investigation of therapeutic strategies.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The Dorsiflexometer is a device designed and built for the assessment of a patient’s balance capabilities. The birth of the Dorsiflexometer is due to a serious need for physiological balance assessment equipment, capable of conducting dynamic tests in the clinical setting. This is accomplished by recording and analysing the patient’s response to sagittal plane perturbations. The Dorsiflexometer is operated from a computer software interface program. It uses the measurements from a single force plate to calculate four balance metrics’ characterising a patient’s ability to maintain balance. These balance metrics include the sway index, equilibrium score, postural stability index and radius parameter. A single and a double inverted pendulum model of the human body is derived to calculate a patient’s centre of mass movement in the sagittal plane with the measured force plate data and body parameters. Three experiments, involving 48 subjects, were conducted. The experimental tests proved the competency of the machine, the accuracy of both inverted pendulum models and the balance response of seafarers aboard an Antarctic research and supply vessel during rough sea conditions. The tests concluded that the inverted pendulum models can be used to calculate the body centre of mass displacement. The double inverted pendulum model results are more accurate compared with the single inverted pendulum model. During rough sea conditions, the body movement and postural response of seafarers are increased in order to keep themselves upright. The body is furthermore exposed to a fluctuating ground reaction force which may lead to the progression of osteoarthritis and musculoskeletal injuries. The Dorsiflexometer proved to be capable of conducting repeatable assessments and yielding accurate results which can be used to distinguish between balance capabilities. / AFRIKKANSE OPSOMMING: Die Dorsiflexometer is ’n apparaat wat die balansvermoë van pasiënte analiseer. Die masjien is ontwerp en vervaardig weens die groot behoefte aan fisiologiese balans assesserings toerusting wat dinamiese toetse in die mediese sektor kan bepaal. Dit word bereik deur pasiënte se liggaamsreaksie in die sagittale vlak te meet en te assesseer. Die Dorsiflexometer is beheerbaar vanaf ’n rekenaar sagteware koppelvlak program. Die masjien maak gebruik van ’n enkele kragplaat om pasiënte se balans statistieke te meet. Hierdie balans statistieke wat die pasiënte se balans vermoë beskryf en karakteriseer behels die sogenaamde: swaai indeks, balans telling, posturale stabiliteit indeks en die radius parameter. ’n Enkel en dubbel inverse slinger model van die liggaam is afgelei. Hierdie modelle maak gebruik van ’n pasiënt se kragplaat metings en sy liggaamlike parameters om die swaartepunt tydens beweging te bereken. Drie eksperimente, waarin 48 persone betrokke was, is gedoen. Die eksperimente is gedoen om die apparaat se bevoegdheid te bewys, die akkuraatheid van altwee inverse slinger modelle te toets en verder die balans van seevaarders op die Antarktiese navorsings en toevoer skip tydens rowwe see toestande te analiseer. Die toetse het bewys dat die inverse modelle gebruik kan word om die liggaam se swaartepunt te bereken. Die dubbel inverse slinger model resultate is wel akkurater as die enkel slinger model. Daar is bevind dat seevaarders van meer liggaamsbeweging en posturale reaksies gebruik moet maak om orent te bly tydens rowwe seetoestande. Verder word hul liggame blootgestel aan ’n wisselende grond reaksie krag wat kan lei tot die ontwikkeling van osteoarthritis en muskuloskeletale beserings. Die Dorsiflexometer is bewys as ’n aparaat wat wat akurate resultate lewer vir herhaalbare assesserings. Dit kan gebruik word om te onderskei tussen verskillende balans vermoëns.

Thesis (M Sport Sc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Many children experience developmental problems without being aware thereof. In a school setting these developmental delays mostly remain unnoticed and are scarcely remediated sufficiently, if at all. Children with developmental deficits often experience movement difficulties and are labelled as clumsy, sloppy or having two left feet. The development of, and proficiency in specific motor skills have been found to play a critical role in the participation of physical activity in children, as well as the maintenance of health and well-being later in life, when entering adulthood. There are, however, countless other factors that affect the optimal development of motor skills and physical activity participation. One such factor is ascribed to instances where children experience problems associated with their environment or the circumstances in which they grow up. Poor socio-economic circumstances and a culturally poor environment, lacking sufficient developmental opportunities, may hinder a child‟s motor skills development and skill learning to such an extent that they cannot reach their full developmental potential. Research suggests that the school environment can provide ample opportunity for the development of motor skills and that all schools should consider implementing motor skills development programmes during the Physical Education (PE) time slots. The mastery of motor skills may influence and benefit the participation in various school sports and may also enhance the ability of children to learn and master new and more complex movement skills within and outside the classroom environment. Thus, due to the fact that children spend a great part of their day at school and in the classroom setting, teachers, especially those facilitating PE, have the opportunity to play a vital role in the acquisition and mastery of important motor skills and subsequently affect the physical activity and developmental future of children. The purpose of this study was to design and implement a motor skills development programme to improve the balance and bilateral coordination of children between the ages of 10 and 12 years in the Stellenbosch region. Two existing classes, from a previously disadvantaged school, were recruited and randomly selected as an experimental (n=35) and control group (n=32). The children completed the Short Form as well as all the Long Form activities for the balance and bilateral coordination subtests of the Bruininks-Oseretsky Test of Motor Proficiency-2 (BOT-2). This was done to provide an overview of the overall motor proficiency and more specifically the level of balance and bilateral coordination. A 12-week motor skills development programme, with a specific focus on balance and bilateral coordination, was designed and implemented by the researcher. The effect of this programme was determined by statistically analysing and comparing the pre- and post-test results with the use of Statistica 2010. The main findings of this study indicated that the intervention programme had a positive, although not statistically significant, effect on the overall motor proficiency and balance and significantly improved bilateral coordination. This study suggests that some of the children, between the ages of 10 and 12, from a previously disadvantaged school in the Stellenbosch region and with access to an established school PE programme, experienced movement difficulties. Consequently, there is great room for improvement and motor skill development in these children. This study can, therefore, be a stepping stone into future research regarding further motor skills research in primary school children, the implementation of expanded motor skills intervention programmes and to improve all the motor skills as opposed to selected motor skills as in this study. / AFRIKAANSE OPSOMMING: Ontwikkelingsprobleme word, sonder dat ʼn mens daarvan bewus is, deur vele kinders ervaar. In die skool-omgewing bly hierdie ontwikkelingsagterstande meestal ongesiens en word min kinders, indien enige, voldoende geremedieer. Kinders met ontwikkelingsagterstande ervaar gereeld bewegingsprobleme en word as lomp, slordig of as iemand met twee linkervoete beskryf. Daar word beweer dat die ontwikkeling van, en vaardigheid in, spesifieke motoriese vaardighede van kinders ʼn kritieke rol in hul deelname aan fisieke aktiwiteit, asook die onderhoud van gesondheid en welstand tydens volwassenheid, speel. Daar is egter talle ander faktore wat die optimale motoriese ontwikkeling en fisieke aktiwiteit deelname van kinders kan beïnvloed. ʼn Voorbeeld van so ʼn faktor word toegeskryf aan gevalle waar kinders probleme, wat met hulle omgewing of die omstandighede waarin hul grootword geassosieer word, ervaar. Swak sosio-ekonomiese omstandighede en ʼn kultureel-arme omgewing, wat tekort skiet aan voldoende ontwikkelingsgeleenthede, mag die motoriese ontwikkeling en die aanleer van nuwe vaardighede tot so ʼn mate inhibeer dat kinders nie in staat is om hulle volle ontwikkelingspotensiaal te bereik nie. Navorsing dui daarop dat die skoolomgewing vele geleenthede vir die ontwikkeling van motoriese vaardighede kan bied en dat daar onderneem moet word om motoriese vaardigheid-ontwikkelingsprogramme tydens Liggaamlike Opvoeding (LO) periodes te implementeer. Die bemeestering van motoriese vaardighede mag die deelname aan verskeie skoolsporte beïnvloed en bevoordeel, asook die vermoë om nuwe en meer komplekse bewegingsvaardighede binne en buite die klasomgewing aan te leer en te bemeester, bevorder. Dus, aangesien kinders ʼn groot gedeelte van hul dag by die skool en in ʼn klasomgewing deurbring, het onderwysers, veral die wat LO fasiliteer, die geleentheid om ʼn noodsaaklike rol in die aanleer en bemeestering van belangrike motoriese vaardighede, en vervolgens fisieke aktiwiteit, asook die toekomstige ontwikkeling van kinders te beïnvloed. Die doel van hierdie studie was om ʼn motoriese vaardigheid-ontwikkelingsprogram, wat balans en bilaterale koördinasie bevorder, vir 10 tot 12-jarige kinders in die Stellenbosch omgewing te ontwerp en implementeer. Twee bestaande klasse vanuit ʼn voorheenbenadeelde skool was gewerf en lukraak verkies as ʼn eksperimentele- (n=35) en kontrolegroep (n=32). Kinders het die kort vorm- asook al die lang vorm-aktiwiteite vir balans en bilaterale koördinasie sub-toetse van die Bruininks-Oseretsky Test of Motor Proficiency-2 (BOT-2) voltooi. Hierdie toetse is afgelê om ʼn oorsig van die algehele motoriese vaardigheidsvlak, en meer spesifiek die vlak van balans en bilaterale koördinasie, te bepaal. ʼn 12-week motoriese vaardigheid-ontwikkelingsprogram, met ʼn spesifieke fokus op balans en bilaterale koördinasie, is deur die navorser ontwerp en geïmplementeer. Die effek van hierdie program is bepaal deur die pre- en post-toets resultate met behulp van Statistica 2010 statisties te analiseer en vergelyk. Die primêre bevindinge van hierdie studie dui daarop dat die intervensieprogram ʼn positiewe, alhoewel nie statisties beduidende, effek op die bevordering van algehele motoriese vaardigheidsvlak en balans, asook ʼn statisties beduidende effek op bilaterale koördinasie gehad het. Hierdie studie dui daarop dat kinders, tussen die ouderdomme van 10 en 12, vanuit ʼn voorheenbenadeelde skool in die Stellenbosch omgewing en wat toegang tot ʼn gevestigde LO program het, steeds bewegingsprobleme ervaar. Dus, is daar groot ruimte vir die verbetering en ontwikkeling van motoriese vaardighede by hierdie kinders. Hierdie studie kan dus as ʼn beginpunt vir toekomstige navorsing in verdere motoriese vaardigheids-navorsing van laerskool kinders, die implementering van uitgebreide motoriese intervensieprogramme, asook die bevordering van alle motoriese vaardighede in vergelyking met geselekteerde motoriese vaardighede soos in die huidige studie dien.

Submitted in fulfillment of Masters Degree in Technology: Chiropractic, Durban University of Technology, Durban, South Africa, 2016. / Background: Myofascial therapies are widely researched with regards to their effects on pain, disability and range of motion. The benefits of such therapies are attributed to the mechanical changes that myofascial therapies are proposed to have on the fascial and myofascial structures. Breakthrough imaging and laboratory techniques, have allowed the in vivo study of these structures, resulting in new hypotheses regarding the roles that connective tissues might play in proprioception. Objectives: The purpose of this investigation was to assess the effects of two myofascial therapies, in terms of immediate changes in navicular pronation, great toe extension measurements and balance tests, as indicated by the postural stability (eyes open and closed) and limits of stability tests. Pre-, post-intervention analysis was used to determine if there were significant changes between the groups. Aims: The myofascial interventions aimed to reduce myofascial restriction and adhesions, within the plantar and crural fasciae’s of individuals with bilateral pronation. Methods: The study recruited 45 subjects with bilateral pronation (2 or more degrees) and randomly allocated them into a placebo ultrasound, ischaemic compression or myofascial release group. Each subject underwent a case history, physical examination, foot, ankle and knee regional examinations, as well as screened for contraindications. A blinded assistant examiner helped measured and record the baseline measurements for navicular position and great toe extension, using a standard two arm goniometer. The researcher then tested participants for postural stability (eyes open, eyes closed) and limits of stability, on the Biosway Portable Balance System. Subjects were then examined and treated bilaterally, for myofascial restrictions in the foot, lower leg and ankle, related or unrelated to the pronation present. Pre- and post-intervention measurements were recorded within a 20 minute window immediately before and after the relevant intervention. Statistical Analysis: Repeated measures ANOVA testing was used to compare the rate of change (between pre- and post-intervention measurements) amongst the three groups, and a p-value <0.05 was considered statistically significant. Post hoc Bonferroni adjusted tests were done to compare all pair wise groups, as well as identify trends between groups. Results and Discussion: The data showed that both myofascial groups, significantly improved in postural stability (eyes closed) overall, post hoc testing showed the ischaemic compression group (p=0.004) and myofascial release group (p=0.031), compared to changes in the placebo ultrasound group.The overall changes were predominantly found in the anterior-posterior axes, with significant improvements in ischaemic compression (p=0.007) and myofascial release group (p=0.053) axes compared to placebo. For the other outcome variables, statistically significant treatment effects were not consistant bilaterally between the groups. Significant (p=0.051) time*group differences for changes in right navicular position. Post hoc testing revealed a borderline significant (p=0.056) improvement in pronation for the myofascial release group in comparison to the ischaemic compression group, which on average got worse. With regards to passive non-weight bearing great toe extension left, significant (p=0.067) improvements for the ischaemic compression group were shown compared to placebo, although this was not consistent for all the great toe extension tests. A borderline significant (p=0.059) time*group effect for postural stability (eyes open) medial-lateral test was obtained. Post hoc Bonferroni adjusted testing showed a non-significant (p=0.063) correlation between the myofascial release group and placebo ultrasound group. Conclusion: The results of this study, rejects the Null hypothesis for changes in balance measurements and suggests that both myofascial interventions had a significant positive outcome for postural stability, compared to placebo. The postural stability (eyes closed) test gave an indication of positive or negative changes in centre of pressure displacement, about the centre of gravity. It is noted that the sham ultrasound, used as a placebo intervention may have produced a treatment effect and is therefore not a reliable placebo measure for this type of investigation. / M

By understanding and mimicking characteristics of postural control used by animals, scientist and engineers may develop standing autonomous robots that work safely within home environments, and treatment strategies that help people overcome postural impairments. To increase our understanding of postural control we developed physical and computational models of standing posture to explain the interrelation of stance width and feedback gain in controlling the stability and dynamics of the postural response. These models facilitated precise analysis of mechanical dynamics and their effects on compliant feedback control, and provided a physical implementation to verify predictions developed from simulation. We show that a scaling of active feedback gain is required to maintain postural stability. These results are consistent with previous studies that have shown that a correlation exists between increased stance width and decreased postural responses. However, these studies have not quantified the relation between stance and the active control of standing posture. This scaling of gains that we show is dependent on the changing kinematic relations of the mechanical structure as it undergoes stance width adjustments. Specifically, we show that increasing stance width increases the leverage of the mechanical system. Feedback gains must be reduced by the reciprocal of the increase in mechanical leverage in order to maintain a consistent postural response; otherwise, the system may become unstable with increasing oscillations. We also showed that increasing magnitudes of intrinsic stiffness increases postural stability by facilitating stable responses over larger ranges of active feedback gain and increasing the stability of responses by decreasing settling time, oscillations, and displacement magnitude. The conclusions of this study were that the variation of mechanical leverage is responsible for changing the dynamics of the response during stance width variation, and that scaling of feedback gains with the changing mechanical leverage of stance width variations is required to maintain consistent response dynamics across stance widths.

The purpose of this thesis was to investigate the influence of postural anxiety on the capacity for Flexible Resource Allocation (FRA) among younger (YA) and older adults (OA). Two experiments were conducted to explore (a) the influence of heightened postural anxiety on the flexible allocation of attention among OA and (b) the influence of concurrent postural challenge and postural anxiety on FRA among YA. Participants performed a postural task concurrently to a cognitive task according to three instructional sets directing task priority. Experiment one revealed that FRA was compromised among OA during circumstances of heightened anxiety. This capacity however, remained available among YA. Therefore, for the second experiment I varied the support surface to explore whether the capacity for FRA could be sustained when posture was challenged beyond static stance. Results indicated that YA altered cognitive task performance according to instructional set without compromising postural stability. These findings suggest that even when posture is challenged during heightened postural anxiety, YA maintain the capacity to automatically allocate attention to a postural task while performing a secondary task. Conversely, it seems that heightened postural anxiety strengthens the attentional bias to posture and subsequently compromises FRA among OA. Overall, results from this thesis suggest that the capacity for FRA is age and situation dependent. / xi, 107 leaves : ill. ; 29 cm

The effect of anxiety on motor learning during a balance relevant task was investigated. Twenty participants (mean age 22.0 ± 2.7 years) were randomly divided into groups that completed the task whilst standing directly on the platform or on 9cm high pedestals, thus constructing Non-Anxious (NA) or Anxious (A) environments. Participants trained for 36 trials in a continuous, pseudo-random oscillating balance task consisting of pseudo-random amplitude translation at 0.5Hz for 45 seconds each on Day 1 and returned for Retention and Transfer tests on Day 2. Motor performance was impaired by training in an anxious environment and this effect persisted across retesting in both non-anxious and anxious environments. Anxiety also tended to further impair transfer of motor performance improvements to a non-anxious environment. These findings have implications for the success of balance training programs in patients who are anxious or afraid of falling. / ix, 103 leaves : ill. ; 29 cm