The thalamus engages in sensation, action, and cognition, but the structure underlying these functions is poorly understood. Thalamic innervation of associative cortex targets several interneuron types, modulating dynamics and influencing plasticity. Is this structure-function relationship distinct from that of sensory thalamocortical systems? Here, we systematically compared function and structure across a sensory and an associative thalamocortical loop in the mouse. Enhancing excitability of mediodorsal thalamus, an associative structure, resulted in prefrontal activity dominated by inhibition. Equivalent enhancement of medial geniculate excitability robustly drove auditory cortical excitation. Structurally, geniculate axons innervated excitatory cortical targets in a preferential manner and with larger synaptic terminals, providing a putative explanation for functional divergence. The two thalamic circuits also had distinct input patterns, with mediodorsal thalamus receiving innervation from a diverse set of cortical areas. Altogether, our findings contribute to the emerging view of functional diversity across thalamic microcircuits and its structural basis.
All data generated or analyzed are included in the manuscript as source data files for Figures 1 to 7.
- Francisco Clasca
- Michael M Halassa
- Michael M Halassa
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All animal experiments were performed according to the guidelines of the US National Institutes of Health and the Institutional Animal Care and Use Committee at the Massachusetts Institute of Technology. Experimental procedures for bouton analysis as shown in figure 4 were approved by the Autonoma de Madrid University ethics committee and the corresponding Madrid Regional Government agency (PROEX175/16), in accordance with the European Community Council Directive 2010/63/UE.
- Mathieu Wolff, CNRS, University of Bordeaux, France
© 2020, Mukherjee et al.
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