Multielectrode analysis of information flow through cat primary visual cortex

Cells in cortical layer 4 contact layer 2+3 neurons that, in turn, send their main intracolumnar output to the infragranular layers. This simple outline of feedforward connections summarizes the main route followed by visual information through cat primary visual cortex. We studied the patterns of connectivity among physiologically identified neurons recorded at different depths within the same, or nearby, cortical columns using multielectrode recordings and cross-correlation analysis. Our preliminarily results suggest that the projection from layer 4 to layers 2+3 is actually split in parallel pathways of information flow that are defined by differences in the dynamic properties of the connections and that may be used to optimally decode the temporal information embedded on every spike train.