Ingham, NJ;
Mcalpine, D;
(2005)
GABAergic inhibition controls neural gain in inferior colliculus neurons sensitive to interaural time differences.
J NEUROSCI
, 25
(26)
6187 - 6198.
10.1523/JNEUROSCI.0146-05.2005.
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Abstract
We investigated the role of GABAergic inhibition on the responses of inferior colliculus (IC) neurons sensitive to interaural time differences (ITDs) in anesthetized guinea pigs. Responses to static and dynamic ITDs were obtained before, during, and after recovery from ionotophoretic application of GABA, or antagonists to the GABA(A) receptor gabazine and bicuculline. For most neurons, a linear relationship was observed between discharge rates evoked by a particular ITD during drug application and control discharge rates. Blocking GABAergic inhibition, or adding exogenous GABA, scaled IC discharge rates in a multiplicative (divisive) and/or additive (subtractive) manner. When the influence of iontophoresed GABA antagonists or exogenous GABA on discharge rates was accounted for, GABAergic inhibition was found to have no effect on the ITD tuning properties of IC neurons. The tuning sharpness of ITD functions, the ITD that evoked 50% response magnitude, and the relative symmetry of ITD functions around their peak response were unaffected by blockade of inhibition or addition of tonic inhibition. However, the ability of neurons to discriminate between ITDs by virtue of differences in their discharge rate was altered by blocking or adding GABA. We propose that inhibition in the IC is involved in the control of the neural gain of the output of IC neurons rather than the regulation of ITD tuning. This gain control appears to arise from a combination of additive and multiplicative processes, and may involve mechanisms such as shunting inhibition or changes in the efficacy of inhibitory and excitatory inputs.
| Type: | Article |
|---|---|
| Title: | GABAergic inhibition controls neural gain in inferior colliculus neurons sensitive to interaural time differences |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1523/JNEUROSCI.0146-05.2005 |
| Keywords: | inferior colliculus, inhibition, GABAergic, interaural time differences, gain control, iontophoresis, TEMPORAL RESPONSE PROPERTIES, SPATIAL RECEPTIVE-FIELDS, MEDIAL SUPERIOR OLIVE, LATERAL LEMNISCUS, SOUND LOCALIZATION, CENTRAL NUCLEUS, DORSAL NUCLEUS, DESCENDING PROJECTIONS, BINAURAL INTERACTION, SHUNTING INHIBITION |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/7846 |
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