Fig 2.

Classification of LGN cells. Each column shows spatial frequency transfer functions for one cell of the indicated response type. Each row shows responses to one stimulus type. The top row shows responses to stimuli modulating only the S-cones and the second row shows responses to achromatic gratings modulating all three cone types in additive phase. The lower row shows responses to R/G (L–M) chromatic modulation. The temporal frequency of the drift was 4 Hz and the orientation was optimised for each cell. The cone contrasts for each stimulus are shown in Table 1. The insets show PSTHs made with a bin width of 10 ms from the response to a low (0.01 cycles/deg) spatial frequency condition in each panel. The phase of Blue On cell responses to achromatic stimuli could be either On or Off and, in this cell, it is Off. The abscissa is 0.25 s and the ordinate 10 impulses/s. The horizontal grey lines show the amplitude of the f1 component of the FFT in the absence of spatial contrast.