A common symptom of Idiopathic Parkinson’s disease (IPD) is decreased trunk and balance control. These deficits in patients with IPD are not treatable, and their underlying mechanisms are not well understood. Additionally, it is not known to what extent decreased trunk control contributes to postural instability in patients with IPD. Previous work by Martin (1965) observed that patients with post-encephalitatic Parkinson’s disease would fall in the direction of the tilt when perturbed while seated. In order to better understand the underlying causes of these observed trunk deficits and attempt to replicate Martins findings, this study investigated postural corrective movement of the trunk while seated in patients with IPD and age-matched healthy controls. Participants’ range of motion (ROM) was tested actively and passively while lying supine, following which, bilateral electromyography (EMG) (rectus abdominis (RA), external oblique (EO), and erector spinae (EST9, L3)) and 3-D kinematic measures were recorded while participants were seated on a modified chair and received unexpected perturbations, 7° at 40°/sec, in four different directions (forward, backward, left, and right). EMG responses were normalized to participant’s maximum voluntary contractions. We observed patients with IPD to have decreased active and passive ROM only in the frontal plane relative to controls. Patterning of muscle responses to rotational perturbations did not vary between groups in any direction, except backward, and trends toward significantly greater EST9 activity were observed during backward and left tilts in patients with IPD. Despite this both patients with IPD and controls were able to make appropriate trunk corrective movements opposite the direction of the tilt. However, two patients, who were most severely affected, did make incorrect trunk movements in the direction of the tilt during left and right tilting perturbations which, upon visual inspection, appear to be due to improperly modulated and timed muscle responses. Thus, our data counters the findings of Martin, and suggests the trunk is posturally stable in IPD. Therefore, balance instabilities during stance are likely due to improper responses of the lower limbs. However, as disease severity increases, the contributing influence of an improperly responding trunk may add to their postural deficits.

Rapid compensatory reach-to-grasp reactions are prevalent and functionally important responses to instability. The need to react very rapidly (to prevent falling) imposes temporal constraints on acquisition and processing of the visuospatial information (VSI) needed to guide the reaching movement. Previous results suggested that the CNS may deal with these constraints by using VSI stored in memory proactively, prior to perturbation-onset; however, the extent to which online visual control is necessary or sufficient to guide these reactions has not been established. Furthermore, the influence of memory-decay and concurrent cognitive-task on the performance of these reactions has not been examined. This Thesis employed a novel paradigm wherein the participant is stationary and a motor-driven handhold is positioned unpredictably in front of the participant for each trial. Reach-to-grasp reactions were evoked in healthy young and older adults by sudden unpredictable antero-posterior platform translation (barriers deterred stepping reactions). Liquid-crystal goggles were used to occlude vision either before (recall-delay time=0s/2s/5s/10s) or after perturbation-onset to force reliance on either stored- or online-VSI, respectively. Participants performed a spatial- or non-spatial-memory task during the delay-time in a subset of trials. When forced to rely on stored-VSI, all participants showed reduction in reach accuracy; however, a tendency to undershoot the handhold was exacerbated in the older adults. Forced-reliance on online-VSI led to similar delays in all participants; however, the older adults were more likely to reach with the “wrong” arm or raise both arms. Comparison with normal-VSI trials suggests that both sources of VSI are utilized when grasping the movable handhold for support, with stored-VSI predominating during initiation/transport and online-VSI contributing primarily to final target acquisition/prehension. In terms of recall-delay, both age groups showed comparable reduction in medio-lateral endpoint accuracy when delay-time was longest. Moreover, both cognitive tasks had similar (slowing) effects in both age-groups, suggesting these effects were related to generic attentional demands. However, the older-adults also showed a dual-task interference effect (poorer cognitive-task performance) that was specific to the spatial-memory-task. Further research is needed to establish whether interventions aimed to improve visual/cognitive processing speed, visuospatial memory, and/or attention capacity can reduce risk of falling among senior populations.

A common symptom of Idiopathic Parkinson’s disease (IPD) is decreased trunk and balance control. These deficits in patients with IPD are not treatable, and their underlying mechanisms are not well understood. Additionally, it is not known to what extent decreased trunk control contributes to postural instability in patients with IPD. Previous work by Martin (1965) observed that patients with post-encephalitatic Parkinson’s disease would fall in the direction of the tilt when perturbed while seated. In order to better understand the underlying causes of these observed trunk deficits and attempt to replicate Martins findings, this study investigated postural corrective movement of the trunk while seated in patients with IPD and age-matched healthy controls. Participants’ range of motion (ROM) was tested actively and passively while lying supine, following which, bilateral electromyography (EMG) (rectus abdominis (RA), external oblique (EO), and erector spinae (EST9, L3)) and 3-D kinematic measures were recorded while participants were seated on a modified chair and received unexpected perturbations, 7° at 40°/sec, in four different directions (forward, backward, left, and right). EMG responses were normalized to participant’s maximum voluntary contractions. We observed patients with IPD to have decreased active and passive ROM only in the frontal plane relative to controls. Patterning of muscle responses to rotational perturbations did not vary between groups in any direction, except backward, and trends toward significantly greater EST9 activity were observed during backward and left tilts in patients with IPD. Despite this both patients with IPD and controls were able to make appropriate trunk corrective movements opposite the direction of the tilt. However, two patients, who were most severely affected, did make incorrect trunk movements in the direction of the tilt during left and right tilting perturbations which, upon visual inspection, appear to be due to improperly modulated and timed muscle responses. Thus, our data counters the findings of Martin, and suggests the trunk is posturally stable in IPD. Therefore, balance instabilities during stance are likely due to improper responses of the lower limbs. However, as disease severity increases, the contributing influence of an improperly responding trunk may add to their postural deficits.

Issued also as thesis, Utrecht.

Issued also as thesis, Utrecht.

A postura bípede reduz a área de apoio e demanda a atuação de um sistema de controle para manter o equilíbrio e a orientação dos segmentos corpóreos. A avaliação postural é muito importante nas intervenções fisioterapêuticas e a busca de sistemas confiáveis para avaliar a postura tem sido uma constante dentro da área. Nesta linha, a avaliação do equilíbrio sagital dado pela relação entre coluna lombar e pelve e pelo ângulo de incidência pélvica (IPE) tem sido usado para as alterações da coluna vertebral. Objetivo: fazer a mensuração dos parâmetros posturais pelo programa de avaliação postural (SAPO) e do equilíbrio sagital pelo programa Keops e fazer a correlação entre eles. Metodologia: foram avaliados 80 indivíduos saudáveis de ambos os sexos com idade entre 20 e 35 anos. Foi feita a biofotogrametria (marcação dos pontos anatômicos do indivíduo e fotografias com os marcadores) do programa SAPO. Foram utilizadas as variáveis obtidas nas vistas lateral esquerda e direita. As medidas dos parâmetros do equilíbrio sagital (ângulo de incidência pélvica é o mais relevante) foram obtidas pela análise de uma radiografia panorâmica em perfil da coluna vertebral, na qual se fazia a marcação digital de pontos anatômicos de referência. O cálculo dos ângulos era feito de forma automática pelo programa Keops. Resultados: pela avaliação do programa Keops: 17,5% dos indivíduos tinham ângulos de incidência pélvica altos ( > 60o), 51,2% tinham ângulos incidência pélvica médios (46-59o) e 31,5% tinham ângulos de incidência pélvica baixos ( < 45o). O SAPO mostrou 12,5% de lordose, 40% de retificação e 47,5% com curvatura normal. Na vista lateral direita, o ângulo de incidência pélvica teve correlação moderada e positiva com o alinhamento vertical do tronco e com o alinhamento vertical do corpo e negativa e moderada com o alinhamento horizontal da pelve. Na vista lateral esquerda o ângulo de incidência pélvica teve correlação fraca e negativa com o alinhamento horizontal da pelve. Não houve correlação entre os parâmetros avaliados pelo programa / Bipedal stance raises the center of mass, reduces the support area, and demands action of the postural control system, which maintains balance and orientation of body segments. Postural alterations may affect the control system, causing pain and motor dysfunctions. Postural assessment is fundamental for therapy recommendation, and some parameters related to the sagittal balance of the lumbar spine and pelvis, like the pelvic incidence angle (PI), have been studied in alterations of the spine. The goal of this study is to assess and look for correlations between postural measurements, with photographs marked in anatomical points, through the Postural Assessment Program (SAPO), and radiographic assessment of the spine to analyze the pelvic incidence angle (PI), using of the computer software Keops. Casuistry and methods: eighty-one healthy individuals of both sexes, aged between twenty and thirty-five were evaluated. Results: in the Keops assessment, 17.5 % of the sample had high pelvic incidence angles ( > 60o), 31.5 % had low pelvic incidence angles ( < 45o), and 51.2 % had medium pelvic incidence angles (between 46o and 59o). SAPO showed 12,5% of lordosis , 40% of retroversion and 47,5% normal curvature.In the right lateral view, the pelvic incidence angle had a moderate and positive correlation with the vertical alignment of the trunk and with the vertical alignment of the body and negative and moderate with the horizontal alignment of the pelvis. In the left lateral view the pelvic incidence angle had a weak and negative correlation with the horizontal alignment of the pelvis. There was no correlation between the parameters evaluated by the Keops program

Orientador: José Angelo Barela / Banca: Sergio Tosi Rodrigues / Banca: Renato de Moraes / Banca: Dora Selma Fix Ventura / Banca: Ana Maria Pellegrini / Resumo: A fim de investigar a utilização da informação visual por crianças e adultos jovens diante de alterações das características do estímulo visual durante a manutenção da posição em pé foram realizados dois experimentos. O primeiro experimento investigou a influência da estrutura do fluxo ótico no acoplamento entre informação visual e oscilação corporal em crianças de 4, 8 e 12 anos de idade e adultos jovens. Os participantes permaneceram em pé dentro de uma sala móvel, em diferentes distâncias da parede frontal da sala, e em três condições: fluxo global, frontal, e lateral. Os resultados indicaram que a influência da distância e da estrutura do fluxo ótico no acoplamento entre informação visual e oscilação corporal foram dependentes da idade e a influência da estrutura do fluxo ótico no acoplamento entre informação visual e oscilação corporal foi dependente da distância. Com base nestes resultados, é possível sugerir que diferenças desenvolvimentais no relacionamento entre informação visual e oscilação corporal estão relacionadas ao modo como as crianças utilizam a informação ótica em diferentes estruturas do fluxo ótico. O segundo experimento investigou a influência de características do estímulo visual no acoplamento entre informação visual e oscilação corporal em crianças de 4, 8 e 12 anos de idade e adultos jovens. Os participantes permaneceram em pé dentro de uma sala móvel em três condições experimentais: diâmetro, contraste, e velocidade do estímulo visual. Os resultados indicaram que o relacionamento temporal entre informação visual e oscilação corporal e a variabilidade do acoplamento entre informação visual e oscilação corporal foram dependentes da idade em todas as condições. O diâmetro e o contraste do estímulo visual não influenciaram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In order to investigate how children and adults use different visual stimulus characteristics during maintenance of upright stance two experiments were designed. The first experiment investigated the influence of optic flow structure in the visual information and body sway coupling of 4-, 8-, and 12-year-old participants and young adults. Participants stood upright inside a moving room at different distances from the frontal wall and at three conditions: global; central; and peripheral optic flow. The results showed that the influence of distance and optic flow structure in the visual information and body sway coupling is age and distance dependent. These results suggest that age-related changes observed in the relationship between visual information and body sway are related to how children use optic information in different optic flow structures. The second experiment investigated the influence of visual stimulus characteristics manipulation in the visual information and body sway coupling of 4-, 8-, and 12-year-old participants and young adults. Participants stood upright inside a moving room with reduced optic flow at three conditions: target with different diameter; contrast; and velocity. The results showed that temporal relationship and variability of coupling between visual information and body sway were age dependent in all conditions. Visual stimulus diameter and visual stimulus contrast did not influence this coupling. Visual stimulus velocity influenced the coupling but this influence was not age dependent. Thus, it can be concluded that age-related changes in coupling between visual information and body sway are not related to different use of stimulus characteristics of the target manipulated in the present experiment. Based upon these results, it can be suggested that the differences in postural control between children and adults... (Complete abstract click electronic access below) / Doutor

M.Tech.

Recent findings have suggested that the type of postural control seems to change, with certain conditions promoting a more conscious control and others, a more automatic control. It has been proposed that by withdrawing attention from postural control, external focus and cognitive task conditions allow automatic mechanisms to control sway more efficiently. The present dissertation aimed to investigate whether two types of postural control exist and to provide evidence for these two types of postural control in healthy young and older adults. In experiment 1, the effect of attentional focus and cognitive tasks was examined in healthy older adults. It was found that the cognitive task yielded improvements in stability compared to focus conditions, which highlighted the fact that automaticity is possible in this group. In experiment 2, the effect of attentional focus and cognitive tasks was once again observed in older adults, this time by including electromyographic recordings of lower leg muscles to examine if changes were due to stiffening. Although improvements were observed in external focus and cognitive task conditions compared to baseline and internal focus, no change occurred in muscle activity which lends further support to the idea that changes are due to automaticity. Finally, dynamic measures of sway were used to help interpret the changes that occurred in attentional focus and cognitive task conditions in both young and older adults. The wavelet transform revealed a change in sensory contributions to postural control in cognitive task conditions. There was a shift to increased contributions from the cerebellum and the vestibular system, and a decrease in visual contributions, compared to other conditions. Sample entropy revealed changes in complexity of sway, with cognitive tasks presenting more complex, irregular and efficient sway in both groups compared to baseline standing and attentional focus conditions. Finally, the rambling-trembling decomposition highlighted increases in the spinal reflex contributions to sway in external focus and difficult cognitive task conditions in young adults, while no change occurred in older adults. Results of these experiments provide the evidence of two types of postural control; a more automatic type in cognitive task conditions and a more conscious type in baseline and internal focus conditions. The external focus elicited some changes that could have indicated automaticity, but clear differences were still present between this condition and the cognitive tasks, which suggest automaticity of sway should be viewed as a continuum.

A common symptom of Idiopathic Parkinson’s disease (IPD) is decreased trunk and balance control. These deficits in patients with IPD are not treatable, and their underlying mechanisms are not well understood. Additionally, it is not known to what extent decreased trunk control contributes to postural instability in patients with IPD. Previous work by Martin (1965) observed that patients with post-encephalitatic Parkinson’s disease would fall in the direction of the tilt when perturbed while seated. In order to better understand the underlying causes of these observed trunk deficits and attempt to replicate Martins findings, this study investigated postural corrective movement of the trunk while seated in patients with IPD and age-matched healthy controls. Participants’ range of motion (ROM) was tested actively and passively while lying supine, following which, bilateral electromyography (EMG) (rectus abdominis (RA), external oblique (EO), and erector spinae (EST9, L3)) and 3-D kinematic measures were recorded while participants were seated on a modified chair and received unexpected perturbations, 7° at 40°/sec, in four different directions (forward, backward, left, and right). EMG responses were normalized to participant’s maximum voluntary contractions. We observed patients with IPD to have decreased active and passive ROM only in the frontal plane relative to controls. Patterning of muscle responses to rotational perturbations did not vary between groups in any direction, except backward, and trends toward significantly greater EST9 activity were observed during backward and left tilts in patients with IPD. Despite this both patients with IPD and controls were able to make appropriate trunk corrective movements opposite the direction of the tilt. However, two patients, who were most severely affected, did make incorrect trunk movements in the direction of the tilt during left and right tilting perturbations which, upon visual inspection, appear to be due to improperly modulated and timed muscle responses. Thus, our data counters the findings of Martin, and suggests the trunk is posturally stable in IPD. Therefore, balance instabilities during stance are likely due to improper responses of the lower limbs. However, as disease severity increases, the contributing influence of an improperly responding trunk may add to their postural deficits. / Education, Faculty of / Kinesiology, School of / Graduate