The reach-to-eat movement, in which a hand is advanced towards a food item, shapes to grasp the food item, and withdrawals to place the food item into the mouth for eating, is a behaviour that is performed daily. The movement is controlled by two sensory systems, vision to guide hand advance and grasping, and somatosensation to guide hand withdrawal and mouth placement. The purpose of the present thesis was to examine how the sensory control of reaching-to-eat develops in infancy and degenerates following neurodegenerative disorder. The tight coupling of vision to hand advance and somatosensation to hand withdrawal has a developmental profile from six months to one year of age. That is, six-month-old infants rely on vision to advance their hand, grasp the target, and withdrawal the target to the mouth. By twelve months of age, infants display the adult pattern of coupling vision to hand advance and grasping. The tight coupling of vision to hand advance degenerates with basal ganglia disease, such that subjects with Parkinson’s disease and Huntington’s disease show an overreliance on vision to guide hand advance for grasping and hand withdrawal for mouth placement. The results of the thesis demonstrate that efficient use of sensory control to guide motor behaviour is an important aspect of development that is disrupted by neurodegenerative disease. / xiv, 286 leaves : ill. ; 29 cm

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 1999. / Vita. Includes bibliographical references (leaves 105-113).

Thesis (M.Sc.)--University of Ottawa, 2008. / Includes bibliographies.

Thesis (M.Sc.)--University of Ottawa, 2008. / Includes bibliographies.

Thesis (Ph. D.)--University of Virginia, 2006. / Includes bibliographical references (leaves 181-233). Also available online through Digital Dissertations.

This study is a multi-method, two-city, intensive, in-depth qualitative study of Huntington's disease (HD) caregivers (HDCs) in Colombia. I explored the Colombia HDCs' experience through the Hispanic culture of caring. I develop the theory of the subrogate agency based on 5 functional stages of HD from Shoulson and Fanh (1979). This study was conducted in two different regions of Colombia, Medellin and Juan de Acosta, in which high rates of HD cases have been identified. The data were collected through three methods: (a) 56 interviews with HDCs and 8 with physicians; (b) 28 participant observations of Huntington's disease sufferers (HDSs); (c) 4 interviews and 8 focus groups of 6 members each with HDCs of late HDSs. Human agency is the ability to monitor one's own action. This study showed that the gradual and serious loss of all capabilities in HDSs has a social effect on the HDSs' agency. HDSs' survival depends on the subrogation that the HDC offers to the HDS. The HDS retains self-hood, i.e. agency, through the HDC's action. This subrogation causes a paradoxical consequence, resulting in both negative and positive effects on the caregiver. The theory of surrogate agency is supported by the data. Through the progressive phases, the capacity of the sufferer for expressing suffering, and social embarrassment, as well as the capacity to fight against the illness and provide reciprocity to their caregivers, deceases. The reason is that physical and cognitive impairments, as well as depression and anger, continue to increase. The study also documented important socio-cultural differences among the study regions. For instance, HDC's solidarity was based on blood and friendship; in larger cities, HD fragmented families. The study also found that HD is taking an immense toll on caregivers, sufferers and families because they are excluded from the Colombia's Basic Health Plan.

Indiana University-Purdue University Indianapolis (IUPUI) / Huntington disease (HD) is an autosomal dominant disorder characterized by progressive decline of motor, cognitive, and behavioral function. Saccades (rapid, gaze-shifting eye movements) are affected before a clinical diagnosis of HD is certain (i.e. during the premanifest period of the disease). Fundamental questions remain regarding the neural substrates of abnormal saccades and the course of premanifest disease. This work addressed these questions using magnetic resonance imaging (MRI) and a longitudinal study of premanifest disease progression. Gray matter atrophy is a characteristic of HD that can be reliably detected during the premanifest period, but it is not known how such changes influence saccadic behavior. We evaluated antisaccades (AS) and memory guided saccades (MG) in premanifest and manifest HD, then tested for associations between impaired saccadic measures and gray matter atrophy in brain regions involved in these saccadic tasks. The results suggest that slowed vertical AS responses indicate cortical and subcortical atrophy and may be a noninvasive marker of atrophic changes in the brain. We also investigated the brain changes that underlie AS impairment using an event-related AS design with functional MRI (fMRI). We found that, in premanifest and manifest HD, blood oxygenation level dependent (BOLD) response was abnormally absent in the pre-supplementary motor area and dorsal anterior cingulate cortex following incorrect AS responses. These results are the first to suggest that abnormalities in an error-related response network underlie early disease-related saccadic changes, and they emphasize the important influence of regions outside the striatum and frontal cortex in disease manifestations. Though saccadic abnormalities have been repeatedly observed cross sectionally, they have not yet been studied longitudinally in premanifest HD. We found different patterns of decline; for some measures the rate of decline increased as individuals approached onset, while for others the rate was constant throughout the premanifest period. These results establish the effectiveness of saccadic measures in tracking premanifest disease progression, and argue for their use in clinical trials. Together, these studies establish the utility of saccade measures as a marker of HD neurodegeneration and suggest that they would be a valuable component of batteries evaluating the efficacy of neuroprotective therapies.

Thesis (Ph. D.)--University of Lund, 1994. / Published dissertation. Includes bibliographical references.

Thesis (Ph. D.)--University of Lund, 1994. / Published dissertation. Includes bibliographical references.