CONCOMITANT SENSITIVITY TO ORIENTATION, DIRECTION, AND COLOR OF CELLSIN LAYER-2, LAYER-3, AND LAYER-4 OF MONKEY STRIATE CORTEX

The receptive field properties of cells in layers 2, 3, and 4 of area 17 (V1) of the monkey were studied quantitatively using colored and br oad-band gratings, bars, and spots. Many cells in all regions studied responded selectively to stimulus orientation, direction, and color. N early all cells (95%) in layers 2 and 3 exhibited statistically signif icant orientation preferences (biases), most exhibited at least some c olor sensitivity, and many were direction sensitive. The degree of sel ectivity of cells in layers 2 and 3 varied continuously among cells; w e did not find discrete regions containing cells sensitive to orientat ion and direction but not color, and vice versa. There was no relation ship between the degree of orientation sensitivity of the cells studie d and their degree of color sensitivity. There was also no obvious rel ationship between the receptive field properties studied and the cells ' location relative to cytochrome oxidase-rich regions. Our findings a re difficult to reconcile with the hypothesis that there is a strict s egregation of cells sensitive to orientation, direction, and color in layers 2 and 3. In fact, the present results suggest the opposite sinc e most cells in these layers are selective for a number of stimulus at tributes.