Control of a depolarizing GABAergic input in an auditory coincidence detection circuit.

Title

Control of a depolarizing GABAergic input in an auditory coincidence detection circuit.

Creator

Tang Zheng-Quan; Gao Hongxiang; Lu Yong

Publisher

Journal of neurophysiology

Date

2009
2009-09

Description

Neurons in the chicken nucleus laminaris (NL), the third-order auditory neurons that detect the interaural time differences that enable animals to localize sounds in the horizontal plane, receive glutamatergic excitation from the cochlear nucleus magnocellularis (NM) and GABAergic inhibition from the ipsilateral superior olivary nucleus. Here, we study metabotropic glutamate receptor (mGluR)- and GABAB receptor (GABABR)-mediated modulation of synaptic transmission in NL neurons. Gramicidin-perforated recordings from acute brain stem slice preparations showed that the reversal potential of the GABAergic responses in NL neurons was more depolarized than the spike threshold. Activation of the GABAergic input produced a mix of inhibitory and excitatory actions in NL neurons. The inhibitory action is known to be critical in improving the acuity of temporal processing of sounds. The excitatory action, however, would reduce the phase locking fidelity of NL neurons in response to their excitatory inputs from the NM. We show that activation of presynaptic mGluRs or GABABRs by either exogenous agonists or synaptically released neurotransmitters reduced the GABAergic responses, preventing the excitatory action of GABA while leaving the inhibitory action intact. Unlike most CNS synapses, the glutamatergic transmission in the NL was not modulated by either mGluRs or GABABRs, indicating that fixed (nonmodulatory) excitatory inputs to the NL may be optimal for coincidence detection. This study contributes to our understanding of how selective neuromodulation is achieved to suit a particular function of neuronal circuits in the brain.

Subject

Animals; Auditory Pathways/physiology; Biophysics; Brain Mapping; Chick Embryo; Cochlear Nucleus/*cytology; Electric Stimulation/methods; Excitatory Amino Acid Agents/pharmacology; GABA Agents/pharmacology; gamma-Aminobutyric Acid/*metabolism/pharmacology; In Vitro Techniques; Inhibitory Postsynaptic Potentials/drug effects/physiology; Nerve Net/*physiology; Neural Inhibition/drug effects/*physiology; Neurons/*physiology; Patch-Clamp Techniques/methods; Synaptic Transmission/drug effects/*physiology; Time Factors

Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

1672–1683

Issue

3

Volume

102

Citation

Tang Zheng-Quan; Gao Hongxiang; Lu Yong, “Control of a depolarizing GABAergic input in an auditory coincidence detection circuit.,” NEOMED Bibliography Database, accessed April 19, 2021, https://neomed.omeka.net/items/show/4668.

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