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bioRxiv · 10.1101/571711

Connectional heterogeneity in the mouse auditory corticocollicular system

Yudintsev, G.·Asilador, A.·Coppinger, M.·Nair, K.·Prasad, M.·Llano, D. A.
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Abstract

The auditory cortex (AC) sends long-range projections to virtually all subcortical structures important for hearing. One of the largest and most complex of these - the projection between AC and inferior colliculus (IC, the corticocollicular pathway) - has attracted attention due to its potential to alter IC response properties. The corticocollicular pathway comprises a component originating from layer 5, but recent evidence suggests a significant contribution from deep layer 6, constituting 25% of corticocollicular neurons in mouse. The functions of layer-specific corticocollicular projections are poorly understood. Here, using a combination of tracers and in vivo imaging, we observed that layer 5 and layer 6 corticocollicular neurons differ in their cortical areas of origin, as well as IC termination patterns. Layer 5 corticocollicular neurons are concentrated in primary AC areas while layer 6 corticocollicular neurons emanate from broad auditory and non-auditory areas of temporal cortex. In addition, layer 5 projects to three IC subdivisions with axo-somatic terminals in the central nucleus, while layer 6 projects to non-central nuclei and targets the most superficial layers. These findings suggest that layer 5 corticocollicular neurons form a direct connection between primary AC and IC while the layer 6 projection is more diffusely organized and carries non-auditory information to modulate IC.

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Yudintsev, G., Asilador, A., Coppinger, M., Nair, K., Prasad, M., Llano, D. A.. 2019-03-08. Connectional heterogeneity in the mouse auditory corticocollicular system. https://doi.org/10.1101/571711

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