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Neuron. 2015 May 6;86(3):768-82. doi: 10.1016/j.neuron.2015.03.040. Epub 2015 Apr 23.

A corticothalamic switch: controlling the thalamus with dynamic synapses.

Author information

1
Department of Neuroscience, Brown University, 185 Meeting Street, Box G-LN, Providence, RI 02912, USA.
2
Department of Neuroscience, Brown University, 185 Meeting Street, Box G-LN, Providence, RI 02912, USA. Electronic address: bc@brown.edu.

Abstract

Corticothalamic neurons provide massive input to the thalamus. This top-down projection may allow the cortex to regulate sensory processing by modulating the excitability of thalamic cells. Layer 6 corticothalamic neurons monosynaptically excite thalamocortical cells, but also indirectly inhibit them by driving inhibitory cells of the thalamic reticular nucleus. Whether corticothalamic activity generally suppresses or excites the thalamus remains unclear. Here we show that the corticothalamic influence is dynamic, with the excitatory-inhibitory balance shifting in an activity-dependent fashion. During low-frequency activity, corticothalamic effects are mainly suppressive, whereas higher-frequency activity (even a short bout of gamma frequency oscillations) converts the corticothalamic influence to enhancement. The mechanism of this switching depends on distinct forms of short-term synaptic plasticity across multiple corticothalamic circuit components. Our results reveal an activity-dependent mechanism by which corticothalamic neurons can bidirectionally switch the excitability and sensory throughput of the thalamus, possibly to meet changing behavioral demands.

PMID:
25913856
PMCID:
PMC4425600
DOI:
10.1016/j.neuron.2015.03.040
[Indexed for MEDLINE]
Free PMC Article

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