Visual properties of neurons in a polysensory area in superior temporal sulcus of the macaque.

dorsal bank and fundus of the anterior por-tion of the superior temporal sulcus, an area we term the superior temporal polysensory area (STP). Five macaques were studied under anesthesia ( N20) and immobilization in repeated recording sessions. 2. Almost all of the neurons were visually responsive, and over half responded to more than one sensory modality; 21 % responded to visual and auditory stimuli, 17 % re-sponded to visual and somesthetic stimuli, 17 % were trimodal, and 41 % were exclu-sively visual. 3. Almost all the visual receptive fields extended into both visual half-fields, and the majority approached the size of the visual field of the monkey, including both monoc-ular crescents. Somesthetic receptive fields were also bilateral and usually included most of the body surface. 4. Virtually all neurons responded better to moving visual stimuli than to stationary visual stimuli, and almost half were sensitive to the direction of movement. Several classes of directional neurons were found, including a) neurons selective for a single direction of movement throughout their receptive field, b) neurons selective for directions of move-ment radially symmetric about the center of gaze, and c) neurons selective for movement in depth. 5. The majority of neurons (70%) had lit-tle or no preference for stimulus size, shape, orientation, or contrast. The minority (30%) responded best to particular stimuli. Some of these appeared to be selective for faces. 6. The properties of most STP neurons, such as large receptive fields, sensitivity to movement, insensitivity to form, and poly-modal responsiveness, suggest that STP is more involved in orientation and spatial functions than in pattern recognition.