The orientation selectivity of single neurons in cat striate cortex.

Abstract

The sensitivity to stimulus orientation — orientation selectivity — of simple and complex neurons in cat striate cortex was studied quantitatively. Orientation selectivity was found to be related to receptive field size — neurons with larger receptive fields being less sensitive to stimulus orientation than those with smaller receptive fields. Simple cells were more orientationally selective than complex cells. The orientation selectivity of simple cells was only weakly related to their receptive field geometry (i.e., receptive field width/length ratio), but simple cells with narrow, elongated excitatory receptive fields are more orientationally selective than those with squarer, excitatory receptive fields. These results indicate that orientation selectivity cannot be accounted for solely by the geometry of the excitatory zones and suggest that inhibitory influences sharpen the tuning of simple striate neurons for stimulus orientation.