The Mammalian Interaural Time Difference Detection Circuit Is Differentially Controlled by GABAB Receptors during Development

Functional localization of neurotransmitter receptors and synaptic inputs to mature neurons of the medial superior olive

“…The presence of functional GABA A Rs together with the histochemical evidence of GABAergic fibers in the MSO (Hassfurth et al 2010;Korada and Schwartz 1999) is suggestive of a direct GABAergic synaptic input to these cells. As before, the pressure application of a high-[K ϩ ] solution at both somatic and distal dendritic locations was used to stimulate synaptic inputs, this time to GABA A Rs (Fig.…”

“…GABAR-mediated synaptic transmission is downregulated during the development of MSO neurons (Smith et al 2000). However, a modulatory role for presynaptic GABA B Rs in the mature MSO has recently been suggested (Hassfurth et al 2010), and there is indication of the presence of GABAergic fibers close to MSO neurons in mature animals (Korada and Schwartz 1999). To identify a postsynaptic GABA effect, the presence of GABA A Rs was probed with UV uncaging of CNB-GABA on the dendrites of mature MSO neurons (n ϭ 13, P30 -35).…”

“…These non-site-specific actions have profound effects on synaptic transmission and cellular computation (Chen et al 2010;Semyanov et al 2004). For example, extrasynaptic receptor activation can affect cell excitability (Ballo et al 2010;Ciruela et al 2010;Luscher et al 1997;van Welie et al 2004) and synaptic short-term plasticity (Chanda and Xu-Friedman 2010;Hassfurth et al 2010;Magnusson et al 2008).…”

“…Here, for example, GABA receptors (GABARs) have been implicated in cell and circuit modulation at different stages of sound processing (Chanda and XuFriedman 2010;Hassfurth et al 2010;Magnusson et al 2008;Paolini et al 1998;Takahashi et al 1998). Recent evidence also suggests a functional role for presynaptic GABA B Rs in the medial superior olive (MSO) (Hassfurth et al 2010).…”

“…Here, for example, GABA receptors (GABARs) have been implicated in cell and circuit modulation at different stages of sound processing (Chanda and XuFriedman 2010;Hassfurth et al 2010;Magnusson et al 2008;Paolini et al 1998;Takahashi et al 1998). Recent evidence also suggests a functional role for presynaptic GABA B Rs in the medial superior olive (MSO) (Hassfurth et al 2010). Given the extremely minimal contribution of GABARs to synaptic currents in the cochlear nucleus (Lim et al 2000), lateral superior olive (LSO) (Couchman et al 2011), and MSO (Smith et al 2000), it is likely that some of these effects are mediated by extrasynaptically located receptors.…”