INFORMATION-FLOW AND TEMPORAL CODING IN PRIMATE PATTERN VISION

We perform time-resolved calculations of the information transmitted a bout visual patterns by neurons in primary visual and inferior tempora l cortices. All measurable information is carried in an effective time -varying firing rate, obtained by averaging the neuronal response with a resolution no finer than about 25 ms in primary visual cortex and a round twice that in inferior temporal cortex. We found no better way f or a neuron receiving these messages to decode them than simply to cou nt spikes for this long. Most of the information tends to be concentra ted in one or, more often, two brief packets, one at the very beginnin g of the response and the other typically 100 ms later. The first pack et is the most informative part of the message, but the second one gen erally contains new information. A small but significant part of the t otal information in the message accumulates gradually over the entire course of the response. These findings impose strong constraints on th e codes used by these neurons.