New measures of functional (but not perceptual) continuity in visual grouping

Abstract

The benzodiazepine, Lorazepam enhances the efficiency of inhibitory GABA-A synapses in the cortex, which stabilize postsynaptic, excitatory activity by synchronizing their own discharges at around 40 Hz. Lorazepam treatment also affects contour integration processes, suggesting GABAA-mediated synchronization may be of direct influence during visuo-perceptual organization. By adding contours orthogonal (but at varying distances) to the unspecified continuances formed by the collinear arrangement of cross elements that flicker asynchronously but in a regularly arranged 3 x 3 element matrix, we found priming by means of 4 synchronized crosses presented in square arrangement was substantially increased when orthogonal contours were placed directly adjacent to the virtual continuances between the crosses, but only following lorazepam administration. We conclude that GABAA-induced inhibition influences directly the coding of relations between spatially separate visual stimuli related to the Gestalt principle of good continuation.