Optogenetic assessment of horizontal interactions in primary visual cortex

J Neurosci. 2014 Apr 2;34(14):4976-90. doi: 10.1523/JNEUROSCI.4116-13.2014.


Columnar organization of orientation selectivity and clustered horizontal connections linking orientation columns are two of the distinctive organizational features of primary visual cortex in many mammalian species. However, the functional role of these connections has been harder to characterize. Here we examine the extent and nature of horizontal interactions in V1 of the tree shrew using optical imaging of intrinsic signals, optogenetic stimulation, and multi-unit recording. Surprisingly, we find the effects of optogenetic stimulation depend primarily on distance and not on the specific orientation domains or axes in the cortex, which are stimulated. In addition, across a wide range of variation in both visual and optogenetic stimulation we find linear addition of the two inputs. These results emphasize that the cortex provides a rich substrate for functional interactions that are not limited to the orientation-specific interactions predicted by the monosynaptic distribution of horizontal connections.

Publication types

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

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / genetics
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism
  • Excitatory Amino Acid Antagonists / pharmacology
  • Female
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Male
  • Microscopy, Confocal
  • Neurons / physiology
  • Optogenetics*
  • Orientation / physiology*
  • Photic Stimulation
  • Quinoxalines / pharmacology
  • Rhodopsin / genetics
  • Rhodopsin / metabolism
  • Synapsins / genetics
  • Synapsins / metabolism
  • Tupaiidae
  • Valine / analogs & derivatives
  • Valine / pharmacology
  • Visual Cortex / cytology
  • Visual Cortex / physiology*
  • Visual Pathways / physiology*


  • Excitatory Amino Acid Antagonists
  • Luminescent Proteins
  • Quinoxalines
  • Synapsins
  • 2,3-dioxo-6-nitro-7-sulfamoylbenzo(f)quinoxaline
  • 2-amino-5-phosphopentanoic acid
  • Rhodopsin
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Valine