Functional synergism between putative gamma-aminobutyrate-containing neurons and pyramidal neurons in prefrontal cortex.

The responses of putative gamma-aminobutyratergic interneurons (fast-spiking) and pyramidal (regular-spiking) cell pairs were compared in monkeys performing visual and memory-guided oculomotor tasks. Both fast- and regular-spiking neurons had similar receptive fields, indicating that gamma-aminobutyratergic interneurons carry a specific informational signal, as opposed to providing nonspecific modulation. However, the responses of the pairs were inverted and the timing of excitatory and inhibitory responses appeared to be phased, a property consistent with gamma-aminobutyrate-mediated shaping of receptive fields. These observations (i) provide evidence that interneurons and pyramidal cells can be differentiated in vivo and (ii) begin to elucidate the role of gamma-aminobutyratergic mechanisms in cognition.