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We describe a region-based shape representation that might be particularly useful from a biological perspective because it promotes the localization of objects, and object parts relative to each other. The proposed medial-point representation is similar to medial-axis type representations, but it is more compact. The medial points are those points along the(More)
Membrane vesicles from rat cerebral cortex were prepared and the functional response of the GABAA receptor was followed by monitoring GABA-activated influx of the radiotracer 36Cl- ion. CuCl2 decreased GABA-activated 36Cl- influx into synaptosomal membrane vesicles. The effect of Cu2+ was concentration dependent (5-500 microM CuCl2) and occurred with(More)
Two relevant dimensions are revealed within which developmental patterns of perceptual organization might be investigated. Within the local-integrative dimension, employing a contour integration task, we found indications that spatial integration develops slowly. We also found reduced contextual modulation of a local target in children employing the(More)
Previous studies have suggested that the integration of orientation information across space is impaired in amblyopia. We developed a method for quantifying orientation-domain processing using a test format that is suitable for clinical application. The test comprises a graded series of cards where each card includes a closed path (contour) of high contrast(More)
Behavioral and electrophysiological studies of schizophrenia have consistently demonstrated impairments in the integration of visual features into unified perceptual representations. Specific brain regions involved in this dysfunction, however, remain to be clarified. This study used functional Magnetic Resonance Imaging (fMRI) to examine the relative(More)
INTRODUCTION Chronic schizophrenia patients have previously demonstrated performance deficits in contour integration tasks. The purpose of this study was to investigate whether schizophrenia patients, spanning a range of illness severity, would demonstrate responsiveness to manipulations that recruit top-down processing strategies involving learning and(More)
The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia initiative highlighted a contour integration test as a promising index of visual integration impairment because of its well-established psychometric properties; its prior validation in healthy adults, patients, and nonhuman primates; and its potential sensitivity to(More)
The present study used an operant conditioning procedure and contour integration stimuli to test three-month-olds' sensitivity to both contour continuity and contour closure. The data demonstrate an immaturity of continuity detection and a lack of closure detection at that age, relative to a previous finding of a heightened sensitivity to closed contours in(More)
PURPOSE Sprinting, bouncing, and spontaneous landings are associated with a forefoot contact whereas walking, running, and jumping are associated with heel-toe foot placement. Because such foot placement strategies influence landing mechanics or the ensuing performance, the purpose of this work was to compare lower extremity kinematics and kinetics and(More)