Enhanced GABA(A) inhibition enhances synchrony coding in human perception

The benzodiazepine, lorazepam enhances the efficiency of local, inhibitory GABA(A) synapses in the cortex, which stabilize postsynaptic, excitatory ac tivity by synchronizing their own discharges at around 40 Hz. Treatment wit h lorazepam has also been shown to adversely influence detection performanc e in perceptual tasks, suggesting a role for GABA(A)-mediated synchronizati on during visuo-perceptual organization. Consistent with these findings we report that reaction times to target stimuli were slower following lorazepa m treatment. However, when targets followed presentation of a synchronized prime, presented within a flickering 40-Hz display matrix, the effects of p riming were amplified relative to baseline and control conditions. We concl ude that enhanced GABAA-induced inhibition enhances stimulus-evoked synchro nization with differential effects upon mechanisms of perceptual segmentati on and grouping. NeuroReport 11:3403-3407 (C) 2000 Lippincott Williams & Wi lkins.