The benzodiazepine, lorazepam enhances the efficiency of local, inhibitory GABAA synapses in the cortex, which stabilize postsynaptic, excitatory activity by synchronizing their own discharges at around 40 Hz. Treatment with lorazepam has also been shown to adversely influence detection performance in perceptual tasks, suggesting a role for GABAA-mediated synchronization during visuo-perceptual organization. Consistent with these findings we report that reaction times to target stimuli were slower following lorazepam treatment. However, when targets followed presentation of a synchronized prime, presented within a flickering 40-Hz display matrix, the effects of priming were amplified relative to baseline and control conditions. We conclude that enhanced GABAA-induced inhibition enhances stimulus-evoked synchronization with differential effects upon mechanisms of perceptual segmentation and grouping.
1Institut für Allgemeine Psychologie, Universität Leipzig, Seeburgstr. 14/20, D-04103 Leipzig, Germany
2Unité INSERM U405, Département de Psychiatrie, Hôpitaux Universitaires de Strasbourg, 1, Place de l'Hôpital, 67091 Strasbourg Cedex, France
3Université Lille 1- SN4 Laboratoire de Neuroscience du Comportement, 59655 Villeneuve d'Ascq, France
4Corresponding Author: Mark A. Elliott
Acknowledgements: This research was supported by Deutsche Forschungsgemeinschaft project grant SCHR 375/8-1 and an EEC Biomed 2 project grant. The authors are indebted to Anne Giersch for assistance during experimentation and valuable advice during preparation of this manuscript.
Received 9 August 2000; accepted 16 August 2000