RT Journal Article SR Electronic T1 Two voltage-dependent K+ conductances with complementary functions in postsynaptic integration at a central auditory synapse JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 8011 OP 8022 DO 10.1523/JNEUROSCI.15-12-08011.1995 VO 15 IS 12 A1 HM Brew A1 ID Forsythe YR 1995 UL http://www.jneurosci.org/content/15/12/8011.abstract AB The medial nucleus of the trapezoid body (MNTB) relays auditory information important for sound source localization. MNTB neurons faithfully preserve the temporal patterning of action potentials (APs) occurring in their single giant input synapse, even at high frequencies. The aim of this work was to examine the postsynaptic potassium conductances that shape the transfer of auditory information across this glutamatergic synapse. We used whole cell patch techniques to record from MNTB neurons in thin slices of rat brainstem. Two types of potassium conductance were found which had a strong influence on an MNTB neuron's postsynaptic response. A small low voltage threshold current, Id, limited the response during each EPSP to a single brief AP. Id was specifically blocked by dendrotoxin (DTX), resulting in additional APs during the tail end of the EPSP. Thus DTX degraded the temporal fidelity of synaptic transmission, since one presynaptic AP then led to several postsynaptic APs. A second conductance was a fast delayed rectifier with a high voltage activation threshold, that rapidly repolarised APs and thus facilitated high frequency AP responses. Together, these two conductances allow high frequency auditory information to be passed accurately across the MNTB relay synapse and separately, such conductances may perform analogous functions elsewhere in the nervous system.