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Researchers used cortical cooling to reversibly inactivate higher-order visual areas in ferrets and observed how this affected visual responses in the auditory cortex. Approximately 50% of visually responsive neurons in auditory cortex lost their visual activity during cooling, confirming that these visual areas directly contribute to multisensory integration. Unexpectedly, about 5% of neurons showed enhanced or new visual responses during inactivation, indicating that these visual areas also suppress alternative visual pathways to auditory cortex.
Why it matters
This study identifies specific neural pathways responsible for cross-modal sensory processing, revealing that multisensory integration involves both direct excitation and complex network gating mechanisms. Understanding these pathways could inform treatments for sensory processing disorders and advance our knowledge of how the brain combines information from different senses.
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Multisensory integration is a fundamental feature of cortical processing, yet the functional pathways that deliver visual signals to the auditory cortex remain poorly understood. While anatomical studies reveal multiple candidate projection routes, demonstrating their causal contribution requires targeted manipulation of neural activity. Here, we used cortical cooling to reversibly inactivate the posteromedial lateral suprasylvian cortex (PMLS) and the adjacent area 21 to determine the functional role of higher-order visual areas in generating visual responses within the auditory cortex of the ferret. Units responsive to sound, light, or combined audiovisual stimuli were found across all sampled auditory fields and cortical depths, with visual responses most prominent within the infragranular layers and the non-tonotopic secondary auditory cortex of the Anterior Ectosylvian Gyrus (AEG). Cortical cooling induced robust, bi-directional, and stimulus-specific modulations of firing rates in AC. Approximately 50% of visually responsive units exhibited a significant decrease or complete elimination of visual activity during cooling, confirming a functional role for visual input from PLMS/area 21 to AC. Surprisingly, cooling also revealed circuit-level complexities: a subset (~5%) of units showed enhanced or newly emergent visual responses during inactivation, suggesting that PMLS/area 21 normally exerts a gating influence over alternative visual pathways. Furthermore, contrary to feedforward anatomical predictions, neurons in the AEG – the region most heavily innervated by the cooled visual areas – were less frequently impacted by cooling than those in PEG. Together, these findings demonstrate that higher visual areas causally shape cross-modal processing in the auditory cortex through a complex mixture of direct excitation and network-level modulation.
Source: Cortical cooling reveals a role for visual cortex in generating visual responses in auditory cortex