Large long-lasting potentiation in the dentate gyrus in vitro during blockade of inhibition.

The generation of long-lasting synaptic potentiation was studied in the dentate gyrus of hippocampal slices before and after blockade of inhibition by application of GABA antagonists. Field potential analysis showed that inhibition in the dentate gyrus is to a large extent dendritically located. During blockade of inhibition, induction of long-lasting potentiation was facilitated, together with a large increase in the maximal potentiation that could be produced. It is suggested that the enhanced production of long-lasting potentiation in inhibition-free slices is related to an increased postsynaptic depolarization in granule cell dendrites.