Neocortical somatostatin-expressing GABAergic interneurons disinhibit the thalamorecipient layer 4

Neuron. 2013 Jan 9;77(1):155-67. doi: 10.1016/j.neuron.2012.11.004.


Subtypes of GABAergic interneurons (INs) are crucial for cortical function, yet their specific roles are largely unknown. In contrast to supra- and infragranular layers, where most somatostatin-expressing (SOM) INs are layer 1-targeting Martinotti cells, the axons of SOM INs in layer 4 of somatosensory cortex largely remain within layer 4. Moreover, we found that whereas layers 2/3 SOM INs target mainly pyramidal cells (PCs), layer 4 SOM INs target mainly fast-spiking (FS) INs. Accordingly, optogenetic inhibition of SOM INs in an active cortical network increases the firing of layers 2/3 PCs whereas it decreases the firing of layer 4 principal neurons (PNs). This unexpected effect of SOM INs on layer 4 PNs occurs via their inhibition of local FS INs. These results reveal a disinhibitory microcircuit in the thalamorecipient layer through interactions among subtypes of INs and suggest that the SOM IN-mediated disinhibition represents an important circuit mechanism for cortical information processing.

Publication types

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

MeSH terms

  • Action Potentials / physiology
  • Animals
  • Animals, Newborn
  • GABAergic Neurons / physiology*
  • Gene Expression Regulation
  • Interneurons / metabolism*
  • Mice
  • Mice, Transgenic
  • Neocortex / cytology
  • Neocortex / metabolism*
  • Neural Inhibition / genetics*
  • Somatostatin / biosynthesis*
  • Somatostatin / genetics
  • Thalamus / cytology
  • Thalamus / metabolism*


  • Somatostatin