Neural development and plasticity of multisensory representations

Abstract

Although we live within a rich multisensory world, it is only relatively recently that we have gained some understanding of the brain mechanisms that serve to bind together information from the different senses. Despite this, our understanding of the developmental progression of events leading up to the mature multisensory state has lagged behind. Recent work carried out in both the primate and the cat models has enriched our understanding of the neural bases of multisensory development. This work has shown that there is a gradual growth in the size of the multisensory neuronal pools in both subcortical and cortical structures during early postnatal life, and that these neurons transition from an early non-integrative mode to a later mode in which they actively synthesize their multisensory inputs. The postnatal window within which these processes mature suggests that early sensory experience is a critical determinant in multisensory development. To assess the role of sensory experience, visual-nonvisual experiences have been eliminated (via dark-rearing) or altered (via spatial- or temporal-disparity rearing). In the absence of early postnatal visual experiences, a mature multisensory circuit fails to develop. In contrast, altering the statistics of early multisensory experiences results in the development of a circuit that reflects these experiences. New work is focused on characterizing the spatial receptive field (SRF) and spatiotemporal receptive field (STRF) architecture of subcortical and cortical multisensory neurons and has shown receptive field microstructure to be a key determinant in the evoked multisensory response. Although focused on the development of multisensory spatial representations, these studies provide important insights for studies examining the maturation of multisensory object representations.