Quantitative Analysis of Cooperation and Structure in the Cat Striate Cortex

We applied information-theoretic methods to multi-electrode array recordings in the primary visual cortex of cats to quantify the cooperation and temporal structure that arises in the responses to drifting sinusoid gratings. When testing small differences in orientation (<10o), the temporal structure and joint firing can contribute information for discriminating responses. The contributions from joint firing proportionally increase with larger populations of cells. We find that the independent rates of individual cells can essentially represent coarser orientation differences. The orientation of the visual stimulus can determine the timing of the response onset, which can generate synchrony across the cortical circuit. Further structure in the responses in the form of intervals also depends on orientation and maintains multi-unit response coordination. We believe that cortical synchronization reliably propagates visual information with greater efficiency and supports greater precision and complexity.