Affiliations: Kennedy Center for Research on Human Development,
Nashville, Tennessee, USA | Department of Hearing and Speech Sciences, Vanderbilt
University, Nashville, Tennessee, USA
Note: [] Corresponding author: David W. Royal, Vanderbilt University,
7110 MRB III, Nashville, TN 37232, USA. Tel.: +1 615 936 7104; Fax: +1 615 936
3745; E-mail: [email protected]
Abstract: Purpose: Previous work has established that the integrative capacity
of multisensory neurons in the superior colliculus (SC) matures over a
protracted period of postnatal life (Wallace and Stein, 1997), and that the
development of normal patterns of multisensory integration depends critically
on early sensory experience (Wallace et al., 2004). Although these studies
demonstrated the importance of early sensory experience in the creation of
mature multisensory circuits, it remains unknown whether the reestablishment of
sensory experience in adulthood can reverse these effects and restore
integrative capacity. Methods: The current study tested this hypothesis
in cats that were reared in absolute darkness until adulthood and then returned
to a normal housing environment for an equivalent period of time. Single unit
extracellular recordings targeted multisensory neurons in the deep layers of
the SC, and analyses were focused on both conventional measures of multisensory
integration and on more recently developed methods designed to characterize
spatiotemporal receptive fields (STRF). Results: Analysis of the STRF
structure and integrative capacity of multisensory SC neurons revealed
significant modifications in the temporal response dynamics of multisensory
responses (e.g., discharge durations, peak firing rates, and mean firing
rates), as well as significant changes in rates of spontaneous activation and
degrees of multisensory integration. Conclusions: These results emphasize
the importance of early sensory experience in the establishment of normal
multisensory processing architecture and highlight the limited plastic
potential of adult multisensory circuits.
Keywords: superior colliculus, multimodal, cat, cross-modal, experiential plasticity
