Serotoninergic control of glycinergic inhibitory postsynaptic currents in rat hypoglossal motoneurons.

This report presents the results of a study of the frequency potentiation of inhibitory postsynaptic currents (IPSCs) in hypoglossal motoneurons and its modulation by serotonin. A release-site model of synaptic plasticity was used to characterize the frequency-related potentiation of evoked IPSCs. Data were obtained to determine if the frequency potentiation of IPSCs occurs as a consequence of a low baseline quantal content of evoked IPSCs using whole cell patch-clamp recordings from hypoglossal motoneurons in the neonatal rat brainstem slice preparation.

The unique inhibitory potentials in motoneurons that occur during active sleep are comprised of minimal unitary potentials.

Loss of muscle tone during active (rapid-eye-movement, REM) sleep is due to the inhibition of motoneurons. This inhibition is manifest in high-gain intracellular electrophysiological records as hyperpolarizing synaptic noise, which includes large amplitude active sleep-specific inhibitory postsynaptic potentials (IPSPs). We report here evidence that the large active sleep-specific IPSPs are comprised of a small number of minimal unitary potentials that are characterized by fast rise-times (10-90% rise-times < or = 0.