title: Regulation of interneuron excitability by gap junction coupling with principal cells.
abstract: Electrical coupling of inhibitory interneurons can synchronize activity across multiple neurons, thereby enhancing the reliability of inhibition onto principal cell targets. It is unclear whether downstream activity in principal cells controls the excitability of such inhibitory networks. Using paired patch-clamp recordings, we show that excitatory projection neurons (fusiform cells) and inhibitory stellate interneurons of the dorsal cochlear nucleus form an electrically coupled network through gap junctions containing connexin36 (Cxc36, also called Gjd2). Remarkably, stellate cells were more strongly coupled to fusiform cells than to other stellate cells. This heterologous coupling was functionally asymmetric, biasing electrical transmission from the principal cell to the interneuron. Optogenetically activated populations of fusiform cells reliably enhanced interneuron excitability and generated GABAergic inhibition onto the postsynaptic targets of stellate cells, whereas deep afterhyperpolarizations following fusiform cell spike trains potently inhibited stellate cells over several hundred milliseconds. Thus, the excitability of an interneuron network is bidirectionally controlled by distinct epochs of activity in principal cells.
authors.affiliation: 1] Neuroscience Graduate Program, Oregon Health and Science University, Portland, Oregon, USA. [2] Vollum Institute and Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon, USA.
authors.forename: Pierre F
authors.initials: PF
authors.lastname: Apostolides
authors.forename: Laurence O
authors.initials: LO
authors.lastname: Trussell
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D055592:Biophysical Phenomena / Q000187:drug effects / Q000235:genetics; D000075402:Channelrhodopsins; D017626:Cochlear Nucleus / Q000166:cytology; D017630:Connexins / Q000172:deficiency / Q000235:genetics; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects / Q000235:genetics; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D008164:Luminescent Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000494:pharmacology; D050599:Vesicular Glutamate Transport Protein 2 / Q000235:genetics; D000097004:Gap Junction delta-2 Protein
chemical_list: D000075402:Channelrhodopsins; D017630:Connexins; D008164:Luminescent Proteins; D018377:Neurotransmitter Agents; D050599:Vesicular Glutamate Transport Protein 2; D000097004:Gap Junction delta-2 Protein