ABSTRACT
Spatial frequency and bandwith characteristics were determined for neurones in cat striate cortex. Responses to drifting sin-wave gratings, optimized for orientation, direction and velocity, were determined over a range of spatial frequencies. Comparative measurements of spatial frequency tuning at constant velocity and at constant temporal drift frequency revealed that, overall, tuning derived by either method was similar. Results were evaluated in relation to neuronal class (simple or complex); cell subclass (standard, intermediate or special), defined by length summation, directionality; and velocity selectivity. Distributions of optimal spatial frequency for simple and complex neurones were comparable. By contrast, bandwidths of simple neurones were markedly narrower than for complex neurones, Standard complex neurones, in turn, had narrower vandwidths than special or intermediate complex neurones. Optimal spaties frequency correlated inversely with optimal velocity, directly with orientation selectivity. Thus, neurones tuned to high spatial frequencies tended to respond optimally to low velocities, and were more sharply orientation selective, than neurones tuned to low spatial frequencies. In binocular nurones, spatial frequency tuning characteristics of the two monocular imputs were compared. For either eye, spatial frequency tuning curves were reproducible over time. In a minority of neurones, spatial frequency characteristics were matched for the two eyes . A Majority showed mismatch in spatial frequency characteristics between the eyes. Individual neurones were tuned to different bands of spatial frequencies through either eye; more sharply spatial-frequency selective through one eye than the other; or had both dissimilar bandwidth and spatial frequency. Changing imput spatial-frequency resulted in profound, systematic shifts in ocular dominance. These were progressive in the case of spatial-frequncy mismatch. In cases of bandwidth, or bandwidth an spatial-frequency mismatch, the eye associated with more sharply-tuned imput exerted relatively greater influence at centre frequencies, the other eye relatively greater influence at extreme frequencies...