The effects of lorazepam on visual integration processes: How useful for neuroscientists?

The effects of psychotropic drugs can be seen as a reversible lesion of the central nervous system. We studied the effect of lorazepam, a benzodiazepi ne facilitating the fixation of GABA on the GABAA receptor. Evidence will b e reviewed that lorazepam affects integration processes, using static fragm ented pictures or compound stimuli. It will be shown how these effects can be dissociated from other peripheral or central effects of the drug. As a w hole, the results suggest that lorazepam improves the detection of disconti nuities between collinear elements, but impairs the detection of discontinu ities between two parallel line-ends. Recent results will be presented that support the hypothesis that lorazepam does not affect integration processe s themselves but modulates the mechanisms involved in the processing of dis continuities, i.e., the processing of line-ends and/or the production of vi rtual lines orthogonal to the line-ends. An understanding of the effects of the drug might give insights into the way these signals are used and modul ated by the visual system.