TY - JOUR T1 - Synaptic Release Generates a Tonic GABA<sub>A</sub> Receptor-Mediated Conductance That Modulates Burst Precision in Thalamic Relay Neurons JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2560 LP - 2569 DO - 10.1523/JNEUROSCI.5100-06.2007 VL - 27 IS - 10 AU - Damian P. Bright AU - M. Isabel Aller AU - Stephen G. Brickley Y1 - 2007/03/07 UR - http://www.jneurosci.org/content/27/10/2560.abstract N2 - Tonic inhibition has emerged as a key regulator of neuronal excitability in the CNS. Thalamic relay neurons of the dorsal lateral geniculate nucleus (dLGN) exhibit a tonic GABAA receptor (GABAAR)-mediated conductance that is correlated with δ-subunit expression. Indeed, consistent with the absence of δ-subunit expression, no tonic conductance is found in the adjacent ventral LGN. We show that, in contrast to the situation in cerebellar granule cells, thalamic δ-subunit-containing GABAARs (δ-GABAARs) do not contribute to a spillover component of IPSCs in dLGN. However, tonic activation of thalamic δ-GABAARs is sensitive to the global level of inhibition, showing an absolute requirement on the synaptic release of GABA. Thus, the tonic conductance is abolished when transmitter release probability is reduced or action potential-evoked release is blocked. We further show that continuous activation of δ-GABAARs introduces variability into the timing of low-threshold rebound bursts. Hence, activation of δ-GABAARs could act to destabilize thalamocortical oscillations and therefore have an important impact on behavioral state. ER -