Receptive Fields of Disparity - Tuned Simple Cells in Macaque

between the two eyes' receptive fields. The phase-shift model proposes that disparity is computed by a difference in the arrangement of ON and OFF subunits between the two eyes' receptive fields. This model is based Harvard Medical School on the hypothesis that simple cell receptive fields are 220 Longwood Avenue well modeled by A Gabor function is a product of a Gaussian and a sine wave. The phase of a Gabor refers to the phase of the sine wave and Summary represents a way to describe the sequence of ON and OFF subunits. The position-shift model can also be rep-Binocular simple cells in primary visual cortex (V1) are resented in terms of a Gabor model, as a shift in the the first cells along the mammalian visual pathway center location of the Gaussian. to receive input from both eyes. Two models of how The shape of the disparity tuning curve of a binocular binocular simple cells could extract disparity informa-simple cell is determined by whether its monocular re-tion have been put forward. The phase-shift model ceptive fields are related through a phase or a position proposes that the receptive fields in the two eyes have shift, assuming the inputs to the cell interact multipli-different subunit organizations, while the position-catively (see Supplemental Appendix 1 at http://www. shift model proposes that they have different overall neuron.org/cgi/content/full/38/1/103/DC1). Position locations. In five fixating macaque monkeys, we re-shifts produce symmetric disparity tuning curves (Figure corded from 30 disparity-tuned simple cells that 1B), while phase shifts produce asymmetric disparity showed selectivity to the disparity in a random dot tuning curves. If one assumes that simple-cell disparity stereogram. High-resolution maps of the left and right tuning curves are inherited by downstream complex eye receptive fields indicated that both phase and po-cells, then measurements of disparity tuning in complex sition shifts were common. Single cells usually showed cells (which are numerous in the monkey) can be used a combination of the two, and the optimum disparity as an indirect assay for the underlying mechanism used was best correlated with the sum of receptive field in simple cells. Applying this method, Prince et al. phase and position shift. (2002a) inferred that both phase and position shifts are common in the monkey. But given that (1) the shape of Introduction the disparity-tuning curve of a complex cell is most likely a result not only of the shape of disparity tuning …