Control of a Depolarizing GABAergic Input in an Auditory Coincidence Detection Circuit Export

@article{citeulike:5713201, abstract = {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. 10.1152/jn.00419.2009}, author = {Tang, Zheng-Quan and Gao, Hongxiang and Lu, Yong}, citeulike-article-id = {5713201}, citeulike-linkout-0 = {http://dx.doi.org/10.1152/jn.00419.2009}, citeulike-linkout-1 = {http://jn.physiology.org/content/102/3/1672.abstract}, citeulike-linkout-2 = {http://jn.physiology.org/content/102/3/1672.full.pdf}, citeulike-linkout-3 = {http://jn.physiology.org/cgi/content/abstract/102/3/1672}, citeulike-linkout-4 = {http://view.ncbi.nlm.nih.gov/pubmed/19571192}, citeulike-linkout-5 = {http://www.hubmed.org/display.cgi?uids=19571192}, day = {1}, doi = {10.1152/jn.00419.2009}, journal = {J Neurophysiol}, month = {September}, number = {3}, pages = {1672--1683}, posted-at = {2009-10-27 01:50:03}, priority = {2}, title = {Control of a Depolarizing GABAergic Input in an Auditory Coincidence Detection Circuit}, url = {http://dx.doi.org/10.1152/jn.00419.2009}, volume = {102}, year = {2009} }

TY - JOUR ID - citeulike:5713201 L3 - citeulike-article-id:5713201 N2 - 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. 10.1152/jn.00419.2009 IS - 3 JF - J Neurophysiol EP - 1683 TI - Control of a Depolarizing GABAergic Input in an Auditory Coincidence Detection Circuit VL - 102 SP - 1672 AU - Tang, Zheng-Quan AU - Gao, Hongxiang AU - Lu, Yong PY - 2009/09/01/ UR - http://dx.doi.org/10.1152/jn.00419.2009 ER -