Representation of foveal visual fields in the ventral bank of the superior temporal sulcus in the posterior inferotemporal cortex of the macaque monkey.

Using anesthetized and immobilized monkeys, this study investigated the representation of the visual field in the superior temporal sulcus in the posterior inferotemporal cortex. Of 1043 neurons in the posterior inferotemporal cortex including the sulcus and the gyrus, and surrounding areas that were tested, 540 (52%) responded to visual stimuli and their receptive fields were mapped. In the ventral bank of the superior temporal sulcus at the level corresponding to the posterior middle temporal sulcus, the foveal visual fields, which were dominant, were represented ventrally and the parafoveal visual fields dorsally. The upper and lower visual fields were represented intermingledly and no segregation between the representation of the upper and lower visual fields was seen. In the lateral convexity of the gyrus, the foveal visual fields were represented dorsally and the peripheral visual fields ventrally with the foveal visual fields being predominant. The upper visual fields were represented posteriorly, however locations and sizes of the representation of the upper and lower visual fields varied between hemispheres. The receptive field sizes of neurons in the sulcus were almost the same as those in the gyrus, and these receptive field sizes were intermediate between those of anterior inferotemporal neurons and V4 neurons. These findings suggest that the cortex in the sulcus in the posterior inferotemporal cortex is involved in the central vision, similarly to the cortex in the gyrus.