The connectivity underlying the orientation selectivity in the infragranular layers of monkey striate cortex

The striate cortex of the monkey was studied with an array of 30 closely spaced microelectrodes. Responses to oriented light bars were recorded simultaneously, and interneuronal connectivity was inferred from spike train correlations of pairs of neurones. Between cells with parallel preferred orientations, interactions were strong at short ranges but negative or only weakly positive at separations of 0.3-0.4 mm. At these distances, the stronger correlations were observed between orthogonally oriented cells. The finding does not explain the generation of orientation selectivity, but it is in agreement with a cooperative principle explaining the spatially regular arrangement of oriented cells.