Tonotopic and multisensory organization of the mouse dorsal inferior colliculus revealed by two-photon imaging

Abstract

1The dorsal (DCIC) and lateral cortices (LCIC) of the inferior colliculus are major targets of the auditory 2 and non-auditory cortical areas, suggesting a role in complex multimodal information processing. 3 However, relatively little is known about their functional organization. We utilized in vivo two-photon 4 Ca 2+ imaging in awake mice expressing GCaMP6s in GABAergic or non-GABAergic neurons in the IC to 5 investigate their spatial organization. We found different classes of temporal response, which we 6 confirmed with simultaneous juxtacellular electrophysiology. Both GABAergic and non-GABAergic 7 neurons showed spatial microheterogeneity in their temporal responses. In contrast, a robust reversed 8 rostromedial-caudolateral gradient of frequency tuning was conserved between the two groups, and 9 even among the subclasses. This, together with the existence of a subset of neurons sensitive to 10 spontaneous movements, provides functional evidence for redefining the border between DCIC and 11 LCIC. 12