04 juinAwareness of visual targets within the field defect of hemianopic patients.04 juin 2012
Speaker: Arash Sahraie, University of Aberdeen
In hemianopic patients, Blindsight type I refer to detection within field defect in the absence of any awareness, whereas type II blindsight refers to above chance detection with reported awareness, but without seeing per se. Systematic sensory stimulation is the principle approach in many sensory and motor impairments in brain damaged patients. The parameters for visual stimulation are crucial in mediating any change. In detailed case studies, evidence for dependency of awareness responses on the stimulus properties will be presented. In addition in a number of cases it appears that the detection ability at early stages of training varies as a function of distance of the stimulated area from the sighted field border. There is a lack of detection ability at retinal locations deep within the field defect. Nevertheless following repeated stimulation and after 5,000 to 10,000 trials, the detection performance improves. Therefore, there appears to be a continuum of performance from no detection, to blindsight type I, and eventually type II detection.
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