Interrelation of Tuning Characteristics in Striate Neurons Sensitive to Cross and Corner

In the cat striate cortex we have found 56 out of 174 neurons that respond on average by a threefold increase of the responses to cross-like or corner figures flashing in the receptive field in comparison to those to a single light bar of preferred orientation. For 27/56 of these neurons tuning to both cross and corner was investigated. 18/27 neurons responded to both stimuli, while 3/27 cells were sensitive only to cross and 6/27 only to corner. The width, selectivity, and quality of tuning to orientation did not differ on average for stimulation by the bar and figures of both types. The characteristics of tuning to the shape of a figure (the angle between its lines) were about the same for cross and corner. We have found a direct relationship between the orientation tuning width, selectivity and quality for bar, cross, and corner. The relationships between the characteristics of tuning to the shape of a figure were found to be rather more complex. Thus, among 18 cells sensitive to both cross and corner we never met a high selectivity to cross, whereas that was typical for the selectivity to corner. Of the cells sensitive to cross, 35/46 responded to figures with angles of 45° or 90° between the lines, and the rest (11/46) responded to a cross with an angle of 67.5°. The neurons sensitive to corner responded most often to the angle of 67.5° (9/26) and in nearly equal but lower proportion to all other angles. The functional implication of neuronal sensitivity to cross and corner figures is discussed.