title: Dense, unspecific connectivity of neocortical parvalbumin-positive interneurons: a canonical microcircuit for inhibition?
abstract: GABAergic interneurons play a major role in the function of the mammalian neocortex, but their circuit connectivity is still poorly understood. We used two-photon RuBi-Glutamate uncaging to optically map how the largest population of cortical interneurons, the parvalbumin-positive cells (PV+), are connected to pyramidal cells (PCs) in mouse neocortex. We found locally dense connectivity from PV+ interneurons onto PCs across cortical areas and layers. In many experiments, all nearby PV+ cells were connected to every local PC sampled. In agreement with this, we found no evidence for connection specificity, as PV+ interneurons contacted PC pairs similarly regardless of whether they were synaptically connected or not. We conclude that the microcircuit architecture for PV+ interneurons, and probably neocortical inhibition in general, is an unspecific, densely homogenous matrix covering all nearby pyramidal cells.
authors.affiliation: HHMI, Department of Biological Sciences, Columbia University, New York, New York 10027, USA. adampacker@gmail.com
authors.forename: Adam M
authors.initials: AM
authors.lastname: Packer
authors.forename: Rafael
authors.initials: R
authors.lastname: Yuste
mesh_terms: D000818:Animals; D001931:Brain Mapping / Q000379:methods; D005260:Female; D066298:In Vitro Techniques; D007395:Interneurons / Q000502:physiology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000379:methods; D019579:Neocortex / Q000033:anatomy & histology / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology* / Q000502:physiology*; D010320:Parvalbumins / Q000235:genetics; D018408:Patch-Clamp Techniques / Q000379:methods; D017966:Pyramidal Cells / Q000502:physiology
chemical_list: D010320:Parvalbumins