The Spatial Extent of Optogenetic Silencing in Transgenic Mice Expressing Channelrhodopsin in Inhibitory Interneurons

Cell Rep. 2019 Oct 29;29(5):1381-1395.e4. doi: 10.1016/j.celrep.2019.09.049.


Optogenetic stimulation of inhibitory interneurons has become a commonly used strategy for silencing neuronal activity. This is typically achieved using transgenic mice expressing excitatory opsins in inhibitory interneurons throughout the brain, raising the question of how spatially extensive the resulting inhibition is. Here, we characterize neuronal silencing in VGAT-ChR2 mice, which express channelrhodopsin-2 in inhibitory interneurons, as a function of light intensity and distance from the light source in several cortical and subcortical regions. We show that light stimulation, even at relatively low intensities, causes inhibition not only in brain regions targeted for silencing but also in their subjacent areas. In contrast, virus-mediated expression of an inhibitory opsin enables robust silencing that is restricted to the region of opsin expression. Our results reveal important constraints on using inhibitory interneuron activation to silence neuronal activity and emphasize the necessity of carefully controlling light stimulation parameters when using this silencing strategy.

Keywords: ArchT; VGAT-ChR2; channelrhodopsin; inhibitory interneurons; neuronal silencing; optogenetics; spatial specificity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Channelrhodopsins / metabolism*
  • Gene Silencing*
  • Hippocampus / metabolism
  • Interneurons / metabolism*
  • Light
  • Male
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Neural Inhibition*
  • Opsins / metabolism
  • Optogenetics*
  • Somatosensory Cortex / metabolism
  • Thalamus / metabolism
  • Vesicular Inhibitory Amino Acid Transport Proteins / metabolism


  • Channelrhodopsins
  • Opsins
  • Vesicular Inhibitory Amino Acid Transport Proteins
  • Viaat protein, mouse