Society for Neuroscience 2002
Prog#160.7

VISUAL RESPONSE PROPERTIES OF PRESUMED INHIBITORY NEURONS IN THE INFERIOR TEMPORAL CORTEX OF MACAQUE MONKEY
H. Tamura1*; H. Kaneko2; K. Kawasaki1; I. Fujita1
1. Graduate School of Frontier Bioscience, Osaka University, Toyonaka, Japan
2. National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan

Neurons within area TE of the inferior temporal cortex respond to images of particular objects. The neural basis of the response selectivity of TE neurons, however, is largely unknown. We addressed the mechanism whereby the inhibitory interaction within the TE contributes to selectivity by examining the visual response properties of presumed inhibitory neurons. We applied cross-correlation analysis to spike trains recorded simultaneously from pairs of adjacent neurons in area TE of 4 anesthetized monkeys (Macaca fuscata). A neuron in a pair whose activity decreased the activity of its partner was presumed to be an inhibitory neuron. Out of 455 neurons, 49 were classified as inhibitory neurons. Most of the presumed inhibitory neurons were visually responsive. On average, these neurons increased the rate of firing in response to 10% of the stimuli within the stimulus set, which consisted of geometric figures and object photographs. Similarities in overall stimulus preferences were lower between members of pairs of neurons with an inhibitory linkage than those with either common inputs or excitatory linkages. In addition, the smaller the similarity between the overall stimulus preferences, the stronger the inhibitory interactions. These results indicate that inhibitory neurons in area TE are driven selectively by specific visual images; robust inhibition occurs among adjacent neurons with differing stimulus preferences, suggesting that local inhibitory interactions contribute to shaping stimulus selectivity of TE neurons.