Callosal projections drive neuronal-specific responses in the mouse auditory cortex.
In the auditory cortex (AC), interhemispheric communication is involved in sound localization processes underlying spatial hearing. However, the neuronal microcircuits recruited by the callosal projections are unknown. We addressed this fundamental question by taking advantage of optogenetics and examining directly the functional effects of interhemispheric inputs to specific pyramidal neurons in layer 5 of the mouse AC, defined by their output as either corticocortical (CCort) or corticocollicular (CCol). We found that callosal projections suppress the activity of CCort pyramidal neurons, but facilitate firing of CCol pyramidal neurons. This difference is mechanistically explained by callosal activation of fast-spiking parvalbumin-expressing interneurons (FS-PARV), which provide selective inhibition to CCort pyramidal neurons. Our results establish two distinct previously unknown cortical circuits underlying either callosal suppression (callosal projections → FS-PARV → CCort) or facilitation (callosal projections → CCol) of projecting neurons in layer 5 of the AC and attribute a specific function to a genetically defined type of interneuron in interhemispheric communication.
Department of Biology, Neuroscience Institute, University of Texas at San Antonio, San Antonio, Texas 78249.
Crystal
http://orcid.org/0000-0002-6986-6166
C
Rock
Department of Biology, Neuroscience Institute, University of Texas at San Antonio, San Antonio, Texas 78249 alfonso.apicella@utsa.edu.
Alfonso Junior
AJ
Apicella
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology*; D001306:Auditory Pathways / Q000502:physiology*; D000075402:Channelrhodopsins; D003337:Corpus Callosum / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000235:genetics / Q000502:physiology; D066298:In Vitro Techniques; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009415:Nerve Net / Q000502:physiology*; D062308:Optogenetics; D010320:Parvalbumins / Q000235:genetics; D018408:Patch-Clamp Techniques; D011506:Proteins / Q000235:genetics; D017966:Pyramidal Cells / Q000502:physiology*
D000075402:Channelrhodopsins; D008164:Luminescent Proteins; D010320:Parvalbumins; D011506:Proteins; C472408:ROSA22 protein, mouse
auditory cortex; excitation; feedforward; inferior colliculus; inhibition; interhemispheric communication