title: Ambient GABA-activated tonic inhibition sharpens auditory coincidence detection via a depolarizing shunting mechanism.
abstract: Tonic inhibition mediated by extrasynaptic GABA(A) receptors (GABA(A)Rs) has emerged as a novel form of neural inhibition in the CNS. However, little is known about its presence and function in the auditory system. Using whole-cell recordings in brain slices, we identified a tonic current mediated by GABA(A)Rs containing the δ subunit in middle/high-characteristic-frequency neurons of the chicken nucleus laminaris, the first interaural time difference encoder that computes information for sound localization. This tonic conductance was activated by ambient concentrations of GABA released from synaptic vesicles. Furthermore, pharmacological manipulations of the conductance demonstrated its essential role in coincidence detection. Remarkably, this depolarizing tonic conductance was strongly inhibitory primarily because of its shunting effect. These results demonstrate a novel role for tonic inhibition in central auditory information processing.
authors.affiliation: Department of Anatomy and Neurobiology, Northeastern Ohio Universities Colleges of Medicine and Pharmacy, Rootstown, Ohio 44272, USA.
authors.forename: Zheng-Quan
authors.initials: ZQ
authors.lastname: Tang
authors.forename: Emilie Hoang
authors.initials: EH
authors.lastname: Dinh
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Yong
authors.initials: Y
authors.lastname: Lu
mesh_terms: D000818:Animals; D001306:Auditory Pathways / Q000502:physiology*; D015153:Blotting, Western; D002642:Chick Embryo; D004558:Electric Stimulation; D053444:Inhibitory Postsynaptic Potentials; D008564:Membrane Potentials / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011963:Receptors, GABA-A / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid