Study reveals visual cortex's causal role in generating visual responses in auditory cortex
Researchers used cortical cooling in ferrets to demonstrate that higher-order visual areas causally contribute to visual responses observed in the auditory cortex. The study found that approximately 50% of visually responsive auditory neurons lost their visual responses when visual cortex was inactivated, while some neurons showed enhanced responses, suggesting complex gating mechanisms. These findings advance understanding of multisensory integration in the brain and challenge simple feedforward models of cross-modal processing.
A new study published on bioRxiv used reversible cortical cooling to inactivate visual cortex regions (PMLS and area 21) in ferrets while recording neural activity in the auditory cortex. Researchers found that visual responses were widespread across auditory cortical fields and depths, with the strongest responses in deeper layers and non-tonotopic secondary auditory regions. Cooling-induced inactivation of visual areas caused robust, stimulus-specific changes in auditory neuron firing: about 50% of visually responsive units showed decreased or eliminated visual responses, confirming a direct functional pathway. Unexpectedly, approximately 5% of units exhibited enhanced or newly emergent visual responses during cooling, indicating that visual cortex normally gates alternative visual input pathways to auditory cortex. The findings also revealed that neurons in regions most heavily innervated by cooled visual areas were paradoxically less affected than those in other auditory regions, suggesting circuit-level complexities beyond simple feedforward connectivity.
What's missing
The study's own limitations and open questions include: whether findings generalize to other species including primates; the identity and anatomical routes of the alternative visual pathways that emerge during PMLS/area 21 inactivation; the functional significance of visual responses in auditory cortex for behavior; and whether similar gating mechanisms operate in other cross-modal pathways.
What different sources said
- bioRxivCenter
Cortical cooling reveals a role for visual cortex in generating visual responses in auditory cortex
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