Flow and Temporal Coding in Primate Pattern

We perform time-resolved calculations of the information transmitted about visual patterns by neurons in primary visual and inferior temporal cortices. All measurable information is carried in an eeective time-varying ring rate, obtained by averaging the neuronal response with a resolution no ner than about 25 ms in primary visual cortex and around twice that in inferior temporal cortex. We found no better way for a neuron receiving these messages to decode them than simply to count spikes for this long. Most of the information tends to be concentrated in one or, more often, two brief packets, one at the very beginning of the response and the other typically 100 ms later. The rst packet is the most informative part of the message, but the second one generally contains new information. A small but signiicant part of the total information in the message accumulates gradually over the entire course of the response. These ndings impose strong constraints on the codes used by these neurons.