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

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Abstract

The dorsal (DCIC) and lateral cortices (LCIC) of the inferior colliculus are major targets of the auditory and non-auditory cortical areas, suggesting a role in complex multimodal information processing. However, relatively little is known about their functional organization. We utilized in vivo two-photon Ca²⁺ imaging in awake mice expressing GCaMP6s in GABAergic or non-GABAergic neurons in the IC to investigate their spatial organization. We found different classes of temporal responses, which we confirmed with simultaneous juxtacellular electrophysiology. Both GABAergic and non-GABAergic neurons showed spatial microheterogeneity in their temporal responses. In contrast, a robust, double rostromedial-caudolateral gradient of frequency tuning was conserved between the two groups, and even among the subclasses. This, together with the existence of a subset of neurons sensitive to spontaneous movements, provides functional evidence for redefining the border between DCIC and LCIC.

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Source data files have been provided for Figures 1,4-8, and Figure 3 -figure supplement 1.

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Aaron Benson Wong

Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1650-2710
J Gerard G Borst

Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands

For correspondence
g.borst@erasmusmc.nl

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-6092-1544

Funding

Agentschap NL (FES0908)

J Gerard G Borst

European Commission (660157-OPTIMAPIC)

Aaron Benson Wong
J Gerard G Borst

ZonMw (91218033)

Aaron Benson Wong
J Gerard G Borst

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All experiments in this study were performed in accordance with the ethical guidelines for laboratory animals within our institute and with European guidelines. The study was carried out under the project license (AVD2016789) approved by the Centrale Commissie Dierproeven (CCD) and the animal ethical committee (Instantie voor Dierenwelzijn; IvD) of the Erasmus MC. All recovery surgeries were performed under general isoflurane anesthesia supplemented with lidocaine, carprofen and buprenorphine as peri-operative analgesics. Terminal transcardiac perfusion was performed under pentobarbital anesthesia. Every effort was made to minimize suffering.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.