[Temporal correlations and coding of information in the visual cortex of the cat]

We have observed repeated patterns in evoked spike trains recorded from the primary visual cortex of the cat. These patterns are called "triplets" and "ghost doublets". Triplets are groups of three pulses, that may or may not be adjacent to one other, the mutual intervals of which are replicated in one other group of three spikes with a precision higher than 0.15 ms. Ghost doublets are doublets of pulses whose interval replicates, with the above precision, one of the intervals of the repeated triplets and are also present in the record. In one of the 9 recorded cells, in which pulses were clearly emitted in bursts in phase with the drifting of the sinusoidal grating used as a stimulus, we could show that local temporal correlations in the form of replicating triplets and ghost doublets correspond very precisely to the temporal phase of the grating: the study of the distance between triplets, or between triplets and ghost doublets, gives a remarkably precise value of the time frequency of the grating.