LESS SEGREGATED PROCESSING OF VISUAL INFORMATION IN V2 THAN IN V1 OF THE MONKEY VISUAL-CORTEX

To test the possibility of cross-talk between parallel pathways dealin g with different aspects of visual information, such as orientation, d irection of motion and colour in cortical area V2, we quantitatively a nalysed visual responses of 121 V2 cells recorded from anaesthetized a nd paralysed macaques and compared them with those of 147 V1 cells. A selectivity index of visual responses was calculated for each neuron, which was then classified as selective or not to a particular attribut e of Visual stimuli. Twenty-one percent of the V2 neurons had dual sel ectivity to both colour and direction of stimulus motion (C&D cells). In V1, only 5% of the cells were C&D cells. Thus, the proportion of C& D cells significantly increased from V1 to V2. We also carried out cro sscorrelation analysis of spike trains recorded simultaneously from pa irs of V2 neurons or pairs of V1 neurons. In V2, correlated firings co uld be observed between cells with completely different optimal orient ation, such as orthogonal, while it was never observed in V1. The cros s-correlation analysis further indicated that functional interactions in V2 were more widespread than those in V1. These results suggest tha t neurons which have different functional properties become less segre gated, and that functional interactions become more widespread in V2 t han in V1.