Convergence of inputs from the basal ganglia with layer 5 of motor cortex and cerebellum in mouse motor thalamus

Abstract
Data availability
Article and author information
Metrics

Abstract

A key to motor control is the motor thalamus, where several inputs converge. One excitatory input originates from layer 5 of primary motor cortex (M1_L5), while another arises from the deep cerebellar nuclei (Cb). M1_L5 terminals distribute throughout the motor thalamus and overlap with GABAergic inputs from the basal ganglia output nuclei, the internal segment of the globus pallidus (GPi) and substantia nigra pars reticulata (SNr). In contrast, it is thought that Cb and basal ganglia inputs are segregated. Therefore, we hypothesized that one potential function of the GABAergic inputs from basal ganglia is to selectively inhibit, or gate, excitatory signals from M1_L5 in the motor thalamus. Here, we tested this possibility and determined the circuit organization of mouse (both sexes) motor thalamus using an optogenetic strategy in acute slices. First, we demonstrated the presence of a feedforward transthalamic pathway from M1_L5 through motor thalamus. Importantly, we discovered that GABAergic inputs from the GPi and SNr converge onto single motor thalamic cells with excitatory synapses from M1_L5. Separately, we also demonstrate that, perhaps unexpectedly, GABAergic GPi and SNr inputs converge with those from the Cb. We interpret these results to indicate that a role of the basal ganglia is to gate the thalamic transmission of M1_L5 and Cb information to cortex.

Data availability

All data generated or analyzed during this study are represented in the Figures. Mean values and sample variability are listed in the Results section of the text where applicable. Individual data points are represented on the graphs/Figures. In addition, source data files for all quantitate data are provided.

Article and author information

Author details

Kevin P Koster

Department of Neurobiology, University of Chicago, Chicago, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-2935-3427
S Murray Sherman

Department of Neurobiology, University of Chicago, Chicago, United States

For correspondence
msherman@bsd.uchicago.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-1520-2778

Funding

National Institute of Neurological Disorders and Stroke (NS094184)

S Murray Sherman

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 were performed in accordance with protocols approved by the Institutional Animal Care and Use Committee at the University of Chicago.

Copyright

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.