Temporal correlations in modulated evoked responses in the visual cortical cells of the cat

We analysed evoked responses recorded from 97 cells in the visual cortex of 4 adult cats and 8 kittens, stimulated by a drifting sinusoidal grating. A Fourier analysis of the responses allowed us to select 30 cells showing a clear modulating response (relative modulation index greater than 1). The 162 records from these selected cells were scanned to detect precise temporal correlations in the form of replicating triplets and associated "ghost" doublets. Temporal correlations of this nature were observed in these cells. They are about 10 times more abundant in adult cats than in kittens, and mostly observed in infragranular cortical layer cells. The possible role of these precise temporal patterns in information processing in the brain is examined, as well as the relation between this type of temporal correlation with coherent oscillations and principal components waveforms.