Benzodiazepine receptor involvement in the control of receptive field size and responsiveness in primary somatosensory cortex.

Microiontophoretic ejection of 3 benzodiazepines (BZDs), flurazepam, diazepam and midazolam, and of Ro 15-1788 to primary somatosensory cortical neurons altered the nature of the responses evoked by natural stimulation of the cutaneous surface. BZDs raised the thresholds to tactile stimulation and produced a decrease of the receptive field areas of neurons situated in rapidly adapting submodality regions of S1 cortex; these effects of the BZDs were exerted at different apparent potencies. Ro 15-1788 antagonized the BZD-induced receptive field size decreases and threshold changes. When administered alone, this substance sometimes lowered the threshold for tactile activation and slightly enlarged the receptive field size.