In just the last decade, studies of multisensory processing have doubled all preceding efforts and a multitude of behavioral and perceptual manifestations have already been documented. It is widely accepted that differences in these final products of neural processing depend on differences in the arrangement and weighting of relevant neural inputs. However, investigations into the neural bases for multisensory processing have been relatively uncommon and, consequently, only one model of multisensory convergence has been offered despite these disparate effects. In this model, converging excitatory afferents from different sensory modalities combine to enhance responses to spatially and temporally coincident multisensory stimuli in a fashion that is clearly linked to detection and orientation behaviors. Yet some multisensory effects do not obey these conventions and it is the central hypothesis of this proposal that there is more than one form of multisensory convergence. Accordingly, during the previous grant period, a 'new' form of multisensory convergence was discovered in somatosensory cortex whereby excitatory afferents from one modality were modulated by inhibitory inputs from another. In fact, a high proportion (approximately 70%) of seemingly 'unimodal' neurons in the fourth somatosensory cortical area (S IV) was suppressed by inputs from the auditory Field of the Anterior Ectosylvian Sulcus (FAES) by GABA-ergic mechanisms. The goal of the present proposal is to expose the fundamental properties of this 'new' form of multisensory convergence by exploring the connectional, functional and developmental mechanisms which underlie it. As more models of convergence become available, understanding the relationship between a particular afferent architecture and the resulting behavioral or perceptual effect will help devise testable hypotheses by which the mechanisms of multisensory processing can be further manipulated and assessed. Ultimately, by understanding the neural bases for multiple forms of cross-modal architecture, we will gain insight into not only non-tactile influences on tactual processing, but also into broad features underlying behavior and perception relevant to both normal and clinical conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS039460-06
Application #
7057777
Study Section
Cognitive Neuroscience Study Section (COG)
Program Officer
Babcock, Debra J
Project Start
2000-01-01
Project End
2010-02-28
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
6
Fiscal Year
2006
Total Cost
$391,340
Indirect Cost
Name
Virginia Commonwealth University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
105300446
City
Richmond
State
VA
Country
United States
Zip Code
23298
Meredith, M A; Clemo, H R; Lomber, S G (2017) Is territorial expansion a mechanism for crossmodal plasticity? Eur J Neurosci 45:1165-1176
Meredith, M Alex; Lomber, Stephen G (2017) Species-dependent role of crossmodal connectivity among the primary sensory cortices. Hear Res 343:83-91
Meredith, M Alex; Clemo, H Ruth; Corley, Sarah B et al. (2016) Cortical and thalamic connectivity of the auditory anterior ectosylvian cortex of early-deaf cats: Implications for neural mechanisms of crossmodal plasticity. Hear Res 333:25-36
Meredith, M Alex; Allman, Brian L (2015) Single-unit analysis of somatosensory processing in the core auditory cortex of hearing ferrets. Eur J Neurosci 41:686-98
Meredith, M Alex; Allman, Brian L (2012) Early hearing-impairment results in crossmodal reorganization of ferret core auditory cortex. Neural Plast 2012:601591
Meredith, M A; Keniston, L P; Allman, B L (2012) Multisensory dysfunction accompanies crossmodal plasticity following adult hearing impairment. Neuroscience 214:136-48
Foxworthy, W Alex; Meredith, M Alex (2011) An examination of somatosensory area SIII in ferret cortex. Somatosens Mot Res 28:1-10
Meredith, M Alex; Lomber, Stephen G (2011) Somatosensory and visual crossmodal plasticity in the anterior auditory field of early-deaf cats. Hear Res 280:38-47
Keniston, Leslie P; Henderson, Scott C; Meredith, M Alex (2010) Neuroanatomical identification of crossmodal auditory inputs to interneurons in somatosensory cortex. Exp Brain Res 202:725-31
Allman, Brian L; Keniston, Leslie P; Meredith, M Alex (2009) Adult deafness induces somatosensory conversion of ferret auditory cortex. Proc Natl Acad Sci U S A 106:5925-30

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