title: Neocortical somatostatin-expressing GABAergic interneurons disinhibit the thalamorecipient layer 4.
abstract: 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.
authors: Department of Physiology and Neuroscience, Smilow Neuroscience Program, NYU School of Medicine, New York, NY 10016, USA. han.xu@nyumc.org
authors: Han
authors: H
authors: Xu
authors: Hyo-Young
authors: HY
authors: Jeong
authors: Robin
authors: R
authors: Tremblay
authors: Bernardo
authors: B
authors: Rudy
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D059330:GABAergic Neurons / Q000502:physiology*; D005786:Gene Expression Regulation; D007395:Interneurons / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D019579:Neocortex / Q000166:cytology / Q000378:metabolism*; D009433:Neural Inhibition / Q000235:genetics*; D013004:Somatostatin / Q000096:biosynthesis* / Q000235:genetics; D013788:Thalamus / Q000166:cytology / Q000378:metabolism*
chemical_list: D013004:Somatostatin