Mixed excitatory and inhibitory GABA-mediated transmission in chick cochlear nucleus

Research output: Contribution to journalArticle

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Abstract

1. Neurons of the chick nucleus magnocellularis (NM) receive depolarizing GABAergic input from the superior olivary nucleus (SON). We examined the response to exogenous GABA or to stimulation of GABAergic fibres in order to identify the ionic basis of GABAergic synaptic transmission and its physiological implications. 2. Reversal potentials of GABA responses (EGABA) were determined exclusively by the Cl- gradient, measured using whole-cell recording. With gramicidin-perforated patch recording, EGABA was -25 ± 5 mV (mean ± S.D.), and was stable between embryonic day 17 and post-hatch day 10. With normal intracellular Cl-, GABA depolarized neurons by 12 mV. 3. In current clamp, repetitive activation of the GABAergic axons reduced the probability of spiking in response to simultaneous stimulation of excitatory axons. However, IPSPs could themselves elicit action potentials, and facilitation of IPSPs by repetitive activation could lead to a characteristic pattern of spiking. 4. These data indicate that IPSPs with reversal potentials positive to spike threshold may have dual functions, depending on the context of their activation.

Original languageEnglish (US)
Pages (from-to)125-131
Number of pages7
JournalJournal of Physiology
Volume535
Issue number1
DOIs
StatePublished - Aug 15 2001

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Cochlear Nucleus
Inhibitory Postsynaptic Potentials
gamma-Aminobutyric Acid
Axons
Gramicidin
GABAergic Neurons
Patch-Clamp Techniques
Synaptic Transmission
Action Potentials
Neurons

ASJC Scopus subject areas

  • Physiology

Cite this

Mixed excitatory and inhibitory GABA-mediated transmission in chick cochlear nucleus. / Lu, T.; Trussell, Laurence.

In: Journal of Physiology, Vol. 535, No. 1, 15.08.2001, p. 125-131.

Research output: Contribution to journalArticle

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