To make a comprehensive percept of the environment, the brain must take into account inputs from all of its sensory systems. Therefore, at some level in the nervous system, inputs from different sensory modalities must converge onto individual neurons. At present, there is essentially a single model of multisensory processing at the neuronal level: cells in the superior colliculus that receive excitatory afferents from different sensory modalities. However, it is unlikely that the architecture of the midbrain or the excitatory-excitatory nature of its convergent sensory inputs represent the full range of multisensory possibilities. Numerous reports indicate that multisensory convergence also occurs within the cerebral cortex. Here, newly identified connections that violate modality-specific borders may provide a different model to examine other possible forms of multisensory interactions. Specifically, projections within the Anterior Ectosylvian Sulcal (AES) cortex from auditory FAES to somatosensory AES (SIV) cross modality boundaries, but the expected bimodal neurons are not evident. This apparent contradiction (and preliminary data) leads to the hypothesis that the FAES-SIV connection represents a form of excitatory-inhibitory multisensory convergence. Furthermore, these intermodal connections may provide a ready-made substrate on which cross-modal plasticity can it an occur as a result of abnormal postnatal sensory experience. These possibilities will be tested using neuroanatomical and pharmacophysiological methods both in normal somatosensory (SIV) cortex and in that which has been reorganized by neonatal deafening. Because current search paradigms used to identify multisensory neurons are biased toward neurons which receive convergent excitatory inputs, the proposed experiments are likely to reveal a vastly underestimated source of multisensory processing. The proposed studies will also elucidate the circuitry not only for multisensory convergence, but for AES/""""""""association"""""""" cortex as well. Ultimately, this excitatory-inhibitory model of multisensory convergence will contribute to a comprehensive conceptual framework in which the mechanisms of perceptual, developmental, and plastic features of a broad range of multisensory cortical processes may be interpreted.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS039460-01
Application #
6032696
Study Section
Special Emphasis Panel (ZRG1-IFCN-4 (01))
Program Officer
Nichols, Paul L
Project Start
2000-01-01
Project End
2003-12-31
Budget Start
2000-01-01
Budget End
2000-12-31
Support Year
1
Fiscal Year
2000
Total Cost
$218,947
Indirect Cost
Name
Virginia Commonwealth University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
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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