A corticothalamic switch: controlling the thalamus with dynamic synapses

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


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Central Nervous System Stimulants / pharmacology
  • Channelrhodopsins
  • Excitatory Amino Acid Antagonists / pharmacology
  • Excitatory Postsynaptic Potentials / physiology*
  • In Vitro Techniques
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mice
  • Mice, Inbred ICR
  • Mice, Transgenic
  • N-Methylaspartate / pharmacology
  • Neural Pathways / physiology*
  • Optogenetics
  • Picrotoxin / pharmacology
  • Receptors, Neurotensin / genetics
  • Receptors, Neurotensin / metabolism
  • Somatosensory Cortex / physiology*
  • Synapses / genetics
  • Synapses / physiology*
  • Thalamus / physiology*
  • Valine / analogs & derivatives
  • Valine / pharmacology
  • gamma-Aminobutyric Acid / pharmacology


  • Bacterial Proteins
  • Central Nervous System Stimulants
  • Channelrhodopsins
  • Excitatory Amino Acid Antagonists
  • Luminescent Proteins
  • Receptors, Neurotensin
  • neurotensin type 1 receptor
  • yellow fluorescent protein, Bacteria
  • Picrotoxin
  • gamma-Aminobutyric Acid
  • N-Methylaspartate
  • 2-amino-5-phosphopentanoic acid
  • Valine