CODING STRATEGIES IN MONKEY V1 AND INFERIOR TEMPORAL CORTICES

We would like to know whether the statistics of neuronal responses var y across cortical areas. We examined stimulus-elicited spike count res ponse distributions in V1 and inferior temporal (IT) cortices of awake monkeys. In both areas, the distribution of spike counts for each sti mulus was well described by a Gaussian distribution, with the log of t he variance in the spike count linearly related to the log of the mean spike count. Two significant differences in response characteristics were found: both the range of spike counts and the slope of the log(va riance) versus log(mean) regression were larger in V1 than in IT. Howe ver, neurons in the two areas transmitted approximately the same amoun t of information about the stimuli and had about the same channel capa city (the maximum possible transmitted information given noise in the responses). These results suggest that neurons in V1 use more variable signals over a larger dynamic range than IT neurons, which use less v ariable signals over a smaller dynamic range. The two coding strategie s are approximately as effective in transmitting information.