Deactivation of Sensory-Specific Cortex by Cross-Modal Stimuli

TLDR

Visual and auditory cortices have been viewed as modality‑specific and presumed unaffected by other sensory inputs. fMRI experiments show that auditory input can deactivate the visual cortex and visual input can deactivate the auditory cortex, but this cross‑modal inhibition is absent during simultaneous presentation, indicating that modality‑specific cortices can be switched on or off by inhibitory processes.

Abstract

Visual and auditory cortices traditionally have been considered to be "modality-specific." Thus, their activity has been thought to be unchanged by information in other sensory modalities. However, using functional magnetic resonance imaging (fMRI), the present experiments revealed that ongoing activity in the visual cortex could be modulated by auditory information and ongoing activity in the auditory cortex could be modulated by visual information. In both cases, this cross-modal modulation of activity took the form of deactivation. Yet, the deactivation response was not evident in either cortical area during the paired presentation of visual and auditory stimuli. These data suggest that cross-modal inhibitory processes operate within traditional modality-specific cortices and that these processes can be switched on or off in different circumstances.