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Cereb Cortex. 2015 Aug;25(8):2049-64. doi: 10.1093/cercor/bhu010. Epub 2014 Feb 10.

Flexibility and Stability in Sensory Processing Revealed Using Visual-to-Auditory Sensory Substitution.

Author information

1
Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Hadassah Medical School, Hebrew University of Jerusalem, Jerusalem 91220, Israel Interdisciplinary Center for Neural Computation, The Edmond & Lily Safra Center for Brain Sciences (ELSC), Hebrew University of Jerusalem, Jerusalem 91905, Israel.

Abstract

The classical view of sensory processing involves independent processing in sensory cortices and multisensory integration in associative areas. This hierarchical structure has been challenged by evidence of multisensory responses in sensory areas, and dynamic weighting of sensory inputs in associative areas, thus far reported independently. Here, we used a visual-to-auditory sensory substitution algorithm (SSA) to manipulate the information conveyed by sensory inputs while keeping the stimuli intact. During scan sessions before and after SSA learning, subjects were presented with visual images and auditory soundscapes. The findings reveal 2 dynamic processes. First, crossmodal attenuation of sensory cortices changed direction after SSA learning from visual attenuations of the auditory cortex to auditory attenuations of the visual cortex. Secondly, associative areas changed their sensory response profile from strongest response for visual to that for auditory. The interaction between these phenomena may play an important role in multisensory processing. Consistent features were also found in the sensory dominance in sensory areas and audiovisual convergence in associative area Middle Temporal Gyrus. These 2 factors allow for both stability and a fast, dynamic tuning of the system when required.

KEYWORDS:

audiovisual integration; crossmodal effects; fMRI; multisensory processing; sensory cortices

PMID:
24518756
PMCID:
PMC4494022
DOI:
10.1093/cercor/bhu010
[Indexed for MEDLINE]
Free PMC Article

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