Restorative Neurology and Neuroscience - Volume 28, issue 2

Authors: Royal, David W. | Krueger, Juliane | Fister, Matthew C. | Wallace, Mark T.

Article Type: Research Article

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. Show more

Keywords: superior colliculus, multimodal, cat, cross-modal, experiential plasticity

DOI: 10.3233/RNN-2010-0488

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 259-270, 2010

Authors: Sathian, K. | Stilla, Randall

Article Type: Research Article

Abstract: This review focusses on cross-modal plasticity resulting from visual deprivation. This is viewed against the background of task-specific visual cortical recruitment that is routine during tactile tasks in the sighted and that may depend in part on visual imagery. Superior tactile perceptual performance in the blind may be practice-related, although there are unresolved questions regarding the effects of Braille-reading experience and the age of onset of blindness. While visual cortical areas are clearly more involved in …tactile microspatial processing in the blind than in the sighted, it still remains unclear how to reconcile these tactile processes with the growing literature implicating visual cortical activity in a wide range of cognitive tasks in the blind, including those involving language, or with studies of short-term, reversible visual deprivation in the normally sighted that reveal plastic changes even over periods of hours or days. Show more

DOI: 10.3233/RNN-2010-0534

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 271-281, 2010

Authors: Tremblay, Corinne | Champoux, François | Lepore, Franco | Théoret, Hugo

Article Type: Research Article

Abstract: Purpose: Recent studies suggest that cochlear implant (CI) users have a typical, and perhaps improved, ability to fuse congruent multisensory information. The ability to fuse incongruent auditory and visual inputs, however, remains to be fully investigated. Methods: Here, performance on a classical audiovisual task (the McGurk effect) was assessed in seventeen cochlear-implanted, postlingually deaf individuals with varied degrees of auditory competency. Results: In line with previous studies, our results …revealed audiovisual fusion abilities that were within normal limits in CI users compared to normally-hearing (NH) participants. A different pattern of response emerged, however, when participants' responses were analyzed according to the degree of auditory proficiency with the CI. Although proficient CI users (pCI) and NH participants favoured auditory input when multisensory signals were not fused, only the non-proficient CI users (npCI) relied predominantly on visual cues to resolve audiovisual conflict. This pattern was found despite a similar percentage of fused percepts between pCI users, npCI users and NH participants. Conclusion: These data show a remarkable level of similarity between pCI users and NH individuals in the perception of incongruent audiovisual information, suggesting that optimal auditory performance with the CI is associated with normal fusion of conflicting audiovisual input. Show more

Keywords: Multisensory integration, cochlear implant, deadness, McGurk effect

DOI: 10.3233/RNN-2010-0498

Citation: Restorative Neurology and Neuroscience, vol. 28, no. 2, pp. 283-291, 2010