SUBMILLISECOND AMPA RECEPTOR-MEDIATED SIGNALING AT A PRINCIPAL NEURON-INTERNEURON SYNAPSE

Glutamatergic transmission at a principal neuron-interneuron synapse w as investigated by dual whole-cell patch-clamp recording in rat hippoc ampal slices combined with morphological analysis. Evoked EPSPs with r apid time course (half duration approximate to 4 ms; 34 degrees C) wer e generated at multiple synaptic contacts established on the interneur on dendrites close to the soma. The underlying postsynaptic conductanc e change showed a submillisecond rise and decay, due to the precise ti ming of glutamate release and the rapid deactivation of the postsynapt ic AMPA receptors. Simulations based an a compartmental model of the i nterneuron indicated that the rapid postsynaptic conductance change de termines the shape and the somatodendritic integration of EPSPs, thus enabling interneurons to detect synchronous principal neuron activity.