THE VISUALLY RESPONSIVE NEURON AND BEYOND - MULTISENSORY INTEGRATION IN CAT AND MONKEY

The cat superior colliculus neuron is a major site for the convergence and integration of multisensory information. It is only one of many central nervous system sites in many species where information from several modalities converges. Single cells in cat LS (lateral suprasylvian) and AES (anterior ectosylvian sulcus) and in monkey IPS (intraparietal sulcus) and STS (superior temporal sulcus) were examined. Although the spatial, temporal, and multiplicative characteristics of multisensory integration were most closely examined in cat cortex, all of the observations in monkey were consistent with those described in cat. The multisensory receptive fields of a single neuron overlapped one another in space, such that sensory stimuli that were in close spatial register fell within their excitatory receptive fields and enhanced the neuron's activity; spatially disparate stimuli produced either no interaction or depressed responses. The rules of multisensory integration evident at the level of the single neuron are also consistent with studies of intact behaving animals. The attentive and orientation responses cats make to visual and auditory stimuli were predictable based on the reactions of superior colliculus neurons to these stimuli. The data indicate that the visual responses of many neurons, whether in the superior colliculus or cortex, represent only one facet of their sensory coding capabilities. © 1993, Academic Press Inc.