title: Phasic, suprathreshold excitation and sustained inhibition underlie neuronal selectivity for short-duration sounds.
abstract: Sound duration is important in acoustic communication, including speech recognition in humans. Although duration-selective auditory neurons have been found, the underlying mechanisms are unclear. To investigate these mechanisms we combined in vivo whole-cell patch recordings from midbrain neurons, extraction of excitatory and inhibitory conductances, and focal pharmacological manipulations. We show that selectivity for short-duration stimuli results from integration of short-latency, sustained inhibition with delayed, phasic excitation; active membrane properties appeared to amplify responses to effective stimuli. Blocking GABAA receptors attenuated stimulus-related inhibition, revealed suprathreshold excitation at all stimulus durations, and decreased short-pass selectivity without changing resting potentials. Blocking AMPA and NMDA receptors to attenuate excitation confirmed that inhibition tracks stimulus duration and revealed no evidence of postinhibitory rebound depolarization inherent to coincidence models of duration selectivity. These results strongly support an anticoincidence mechanism of short-pass selectivity, wherein inhibition and suprathreshold excitation show greatest temporal overlap for long duration stimuli.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112;
authors.forename: Rishi K
authors.identifier: http://orcid.org/0000-0002-4229-927X
authors.initials: RK
authors.lastname: Alluri
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112; rose@bioscience.utah.edu.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Rose
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112;
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Hanson
authors.affiliation: Department of Biology, University of Mississippi, Oxford, MS 38677;
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Leary
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, UT 84112;
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Vasquez-Opazo
authors.affiliation: Neuroscience Program, University of California, Davis, CA 95616;
authors.forename: Jalina A
authors.initials: JA
authors.lastname: Graham
authors.affiliation: TalkingApe.org, Redwood City, CA 94063.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Wilkerson
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D001309:Auditory Threshold; D005260:Female; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D008297:Male; D008636:Mesencephalon / Q000166:cytology / Q000502:physiology*; D008954:Models, Biological; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011894:Rana pipiens; D018091:Receptors, AMPA / Q000037:antagonists & inhibitors / Q000502:physiology; D011963:Receptors, GABA-A / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology; D013016:Sound; D013997:Time Factors
chemical_list: D058787:GABA-A Receptor Antagonists; D018091:Receptors, AMPA; D011963:Receptors, GABA-A; D016194:Receptors, N-Methyl-D-Aspartate
keywords: GABA; gabazine; inferior colliculus; synaptic conductance; whole-cell