PARALLEL NATURE OF HIPPOCAMPAL SYNAPTIC PLASTICITY

This study demonstrates that the mechanisms involved in the production of long-term potentiation (LTP) in the hippocampus appear to be indep endent of those which generate shorter-lasting plasticity: but that bo th processes are activated concurrently following an LTP-inducing stim ulus. Adult male Sprague-Dawley rats were anesthetized using either pe ntobarbital or secobarbital to record extracellular field potentials f rom the hippocampal CA1 pyramidal cell layer in response to stimulatio n of commissural afferents. Plasticity was generated by the delivery o f a five-pulse patterned stimulus train, consisting of one priming pul se followed 170 milliseconds later by a burst of four pulses at 200 Hz . While similar LTP was observed in both groups, short-term plasticity was absent in the secobarbital-anesthetized animals. This result sugg ests that different plasticity mechanisms in the hippocampus are activ ated in parallel by the: triggering stimulus. Synapse 30:112-115, 1998 . (C) 1998 Wiley-Liss, Inc.