Tuning to Y-like figures in the cat striate neurons

Sensitivity to symmetric or asymmetric Y-like figures and crosses of different shapes and orientations flashed in the receptive field was studied in 101 neurons of the cat striate cortex (area 17) and compared with their orientation tuning to a single light bar. Selective sensitivity to the Y-like figure (figure/bar response ratio more than 1.25) was found in 78/101 neurons (77.2% of cases) and to the cross-in 54/101 units (53.4%). In 62.5% of neurons with sensitivity to both figures, sensitivity to the Y-like figure was higher than to a cross. Tuning to Y-like figure was typically (60%) selective to both its shape and orientation. The remaining Y-like selective neurons exhibited invariant tuning to orientation and/or shape of the figure. The preferred angles between two lines of Y-like figures were distributed in the range of 22.5-157.5 degrees with slight preference to 90 degrees, while crosses of 45 degrees and 90 degrees angles were preferable. Response magnitudes to a single bar, a Y-like figure and a cross were positively correlated. Possible mechanisms and functional implication of the striate sensitivity to Y-like figures are discussed.