Abstract
Neurons in the superior colliculus (SC) develop the capacity to integrate visual, auditory, and somatosensory information based on the animal's experience with concordant cross-modal cues. This elevates their multisensory responses over the component unisensory responses. When sensory experience is restricted in early life, neurons develop normal complements of multisensory neurons; but are unable to integrate cross-modal stimuli involving the deprived modality. Their responses to these cross-modal cue combinations are no greater than those to the component stimuli. What has not been known is whether experience leads to configurations that grant a neuron the general integrative capability to enhance responses to all cross-modal combinations to which it is sensitive, or if each must be learned separately. To investigate this issue we studied trisensory (visual-auditory-somatosensory) in normal animals, those reared in darkness, and those reared in constant masking noise. The results revealed that neurons learn to integrate cross-modal cues in a combination-specific manner. Thus, while trisensory neurons were able to integrate cross-modal pairs involving non-deprived senses, they were unable to integrate those involving a deprived sense. The findings indicate that developing multisensory integration capabilities does not involve a general change in processing capabilities, but one specific to each cross-modal configuration. The data also underscore the observation that the "default" plan instantiated in the absence of relevant experience renders a neuron responsive to multiple sensory modalities but unable to integrate them and thereby enhance the salience of the originating event. Supported by NIH grants EY016716 and NS036916 and the Tab Williams Foundation.
Meeting abstract presented at VSS 2014