Skip Navigation



Cerebral Cortex Advance Access published online on January 17, 2008
Cerebral Cortex, doi:10.1093/cercor/bhm230
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Allman, B. L.
Right arrow Articles by Meredith, M. A.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Allman, B. L.
Right arrow Articles by Meredith, M. A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2008. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Do Cross-Modal Projections Always Result in Multisensory Integration?

Brian L. Allman1, Ruben E. Bittencourt-Navarrete2, Leslie P. Keniston1, Alexandre E. Medina1, Meng Y. Wang1 and M. Alex Meredith1

1 Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, VA 23298, USA, 2 Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ), Brazil 21941-902

Address correspondence to Brian L. Allman, PhD, Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, 1101 E Marshall Street, Sanger Hall 12-067, Richmond, VA, 23298-0709, USA. Email: ballman2{at}vcu.edu

Convergence of afferents from different sensory modalities has generally been thought to produce bimodal (and trimodal) neurons (i.e., exhibit suprathreshold excitation to more than 1 sensory modality). Consequently, studies identifying cross-modal connections assume that such convergence results in bimodal (or trimodal) neurons that produce familiar forms of multisensory integration: response enhancement or depression. The present study questioned that assumption by anatomically identifying a projection from ferret auditory to visual cortex Area 21. However, electrophysiological recording within Area 21 not only failed to identify a single bimodal neuron but also familiar forms of multisensory integration were not observed either. Instead, a small proportion of neurons (9%; 27/296) showed subthreshold multisensory integration, in which visual responses were significantly modulated by auditory inputs. Such subthreshold multisensory effects were enhanced by {gamma}-aminobutyric acid antagonism, whereby a majority of neurons (87%; 20/23) now participated in a significant, multisensory population effect. Thus, multisensory convergence does not de facto result in bimodal (or trimodal) neurons or the traditional forms of multisensory integration. However, the fact that unimodal neurons exhibited a subthreshold form of multisensory integration not only affirms the relationship between convergence and integration but also expands our understanding of the functional repertoire of multisensory processing itself.

Key Words: auditory cortex • bicuculline methiodide • bimodal neuron • extra striate visual cortex • ferret • subthreshold facilitation


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.