Complex cells increase their phase sensitivity at low contrasts and following adaptation

Abstract

One of the best-known dichotomies in neuroscience is the division of neurons in the mammalian primary visual cortex into simple and complex cells. Simple cells have receptive fields with separate ON and OFF subregions and give phasesensitive responses to moving gratings, whereas complex cells have uniform receptive fields and are phase invariant. The phase sensitivity of a cell is calculated as the ratio of the first Fourier coefficient (F1) to the mean time-average (F0) of the response to moving sinusoidal gratings at 100% contrast. Cells are then classified as simple (F1/F 0 >1) or complex (F1/F0 <1). We manipulated cell responses by changing the stimulus contrast or through adaptation. Th..