Is GABA neurotransmission enhanced in auditory thalamus relative to inferior colliculus?

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the central auditory system. Sensory thalamic structures show high levels of non-desensitizing extrasynaptic GABAA receptors (GABAARs) and a reduction in the redundancy of coded information. The present study compared the inhibitory potency of GABA acting at GABAARs between the inferior colliculus (IC) and the medial geniculate body (MGB) using quantitative in vivo, in vitro, and ex vivo experimental approaches.

Reduced GABA(A) receptor-mediated tonic inhibition in aged rat auditory thalamus.

Age-related deficits in detecting and understanding speech, which can lead to social withdrawal and isolation, have been linked to changes in the central auditory system. Many of these central age-related changes involve altered mechanisms of inhibitory neurotransmission, essential for accurate and reliable auditory processing. In sensory thalamus, GABA mediates fast (phasic) inhibition via synaptic GABA(A) receptors (GABA(A)Rs) and long-lasting (tonic) inhibition via high-affinity (extrasynaptic) GABA(A)Rs, which provide a majority of the overall inhibitory tone in sensory thalamus.

Age-related GABAA receptor changes in rat auditory cortex.

Auditory cortex (AI) shows age-related decreases in pre-synaptic markers for gamma-aminobutyric acid (GABA) and degraded AI neuronal response properties. Previous studies find age-related increases in spontaneous and driven activity, decreased spectral and directional sensitivity, and impaired novelty detection. The present study examined expression of GABA(A) receptor (GABA(A)R) subunit message, protein, and quantitative GABA(A)R binding in young, middle-aged, and aged rat AI, with comparisons with adjoining parietal cortex.

Targeting inhibitory neurotransmission in tinnitus.

Tinnitus perception depends on the presence of its neural correlates within the auditory neuraxis and associated structures. Targeting specific circuits and receptors within the central nervous system in an effort to relieve the perception of tinnitus and its impact on one's emotional and mental state has become a focus of tinnitus research. One approach is to upregulate endogenous inhibitory neurotransmitter levels (e.

Extrasynaptic GABA(A) receptors and tonic inhibition in rat auditory thalamus.

Background: Neural inhibition plays an important role in auditory processing and attentional gating. Extrasynaptic GABA(A) receptors (GABA(A)R), containing α(4)and δ GABA(A)R subunits, are thought to be activated by GABA spillover outside of the synapse following release resulting in a tonic inhibitory Cl(-) current which could account for up to 90% of total inhibition in visual and somatosensory thalamus. However, the presence of this unique type of inhibition has not been identified in auditory thalamus.