Bidirectional associative plasticity of unitary CA3-CA1 EPSPs in the rat
hippocampus in vitro.
Dominique Debanne, Beat H. Ghwiler and Scott M. Thompson.
Brain Research Institute, August Forel-Strasse 1, CH-8029 Zurich,
Switzerland, Tel: +41-1-385-6236, Fax: +41-1-422-2262, E-mail:
thompson@hifo.unizh.ch.
APStracts 4:0052N, 1997.
ABSTRACT
Associative long-term potentiation (LTP) and depression of compound and
unitary CA3-CA1 EPSPs were investigated in rat hippocampal slice cultures. The
induction of LTP with synchronous pairing of synaptic activation and
postsynaptic depolarization resulted in an increase in the amplitude of EPSPs
to the same absolute level, regardless of whether the input was naive or had
been previously depressed by asynchronous pairing of pre- and postsynaptic
activity. Saturated LTP of compound and unitary EPSPs was reversed by
asynchronous pairing and could be re-induced by synchronous pairing. The
likelihood that an action potential in a presynaptic CA3 cell failed to
trigger an unitary EPSP in a postsynaptic CA1 cell decreased after induction
of associative potentiation and increased after induction of associative
depotentiation. These changes in the rate of tranmsission failures were
accompanied by large changes in the amplitude of non-failure EPSPs. We
conclude that the same CA3-CA1 synapses can alternatively undergo associative
potentiation and depression, perhaps through opposite changes in a single
expression mechanism.
Received 9 December 1996; accepted in final form 14 January 1997.
APS Manuscript Number J946-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 19 February 1997