ABSTRACT
The selectivity of single cells for the spatial and temporal qualities of a stimulus is progressively refined in the hierarchy of the primary visual pathway. In the visual cortex of the cat the same characteristics are highly constrained. Low spatial frequency attenuation is very evident in some cells, and spatial frequency bandpass averages 1.4 and 1.8 octaves for simple and complex cells, respectively. Differentiating between response modification by inherent physiological properties of a given cell and by network properties is more difficult. The spatial coverage and location of the stimulus is also a factor in defining the strength of cortical input. Point nonlinearities, manifested primarily in the response vs. contrast function, are generally similar across all cortical cells. Nonlinearities of spatial summation can, however, differ markedly between the simple and complex families of cells.
