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Author Notes:

Correspondence should be addressed to Adriana Galvan, PhD, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, NE, Atlanta, GA 30329. E-mail:agalvan@emory.edu.

A.G., Y.S., and T.W. designed research.

A.G. and X.H. performed research.

A.G. and X.H. analyzed data.

A.G., Y.S., and T.W. wrote the paper.

We thank Jean-Francois Pare, Damien Pittard, Yuxian Ma, and Susan Jenkins for expert technical assistance and Karl Deisseroth for the ChR2 and C1V1 DNA plasmids.

The authors declare no competing financial interests.


Research Funding:

This work was supported by the National Institutes of Health (NIH)/Office of Research Infrastructure Programs (Grant P51-OD011132 to the Yerkes National Primate Research Center), NIH/National Institute of Neurological Disorders and Stroke (NINDS Udall Center Grant P50-NS071669 and Grant GR01-NS083386 to T.W.).


  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Neurosciences & Neurology
  • C1V1
  • ChR2
  • motor cortex
  • motor thalamus
  • optogenetics
  • single unit recording

Effects of Optogenetic Activation of Corticothalamic Terminals in the Motor Thalamus of Awake Monkeys


Journal Title:

Journal of Neuroscience


Volume 36, Number 12


, Pages 3519-3530

Type of Work:

Article | Final Publisher PDF


The role of the corticothalamic projection in the ventral motor thalamus remains poorly understood. Therefore, we studied the electrophysiological responses of neurons in the basal ganglia and cerebellar receiving-territories of the motor thalamus (BGMT and CbMT, respectively) using optogenetic activation of corticothalamic projections in awake rhesus macaques. After injections of viral vectors carrying the excitatory opsins ChR2 or C1V1 into the primary motor and premotor cortices of two monkeys, we used optrodes to light activate opsin-expressing neurons in cortex or their terminals in the thalamus while simultaneously recording the extracellular activity of neuronsin the vicinity of the stimulationsites. Asexpected, light activation of opsinsin the cerebral cortex evoked robust,short-latency increases in firing of cortical neurons. In contrast, light stimulation of corticothalamic terminals induced small-amplitude, long-latency increases and/or decreases of activity in thalamic neurons. In postmortemmaterial, opsins were found to be expressed in cell bodies and dendrites of cortical neurons and along their corticothalamic projections. At the electron microscopic level, opsin labeling was confined to unmyelinated preterminal axons and small terminals that formed asymmetric synapses with dendrites of projection neurons or GABAergic interneurons in BGMT and CbMT and with neurons in the reticular thalamic nucleus. The morphological features of the transfected terminals, along with the long latency and complex physiological responses of thalamic neurons to their activation, suggest a modulatory role of corticothalamic afferents upon the primate ventral motor thalamus.

Copyright information:

© 2016 the authors.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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