The Long-Term Facilitation of Neuronal Activity Produced by Repeated Pairing of an Orthodromic Stimulus and Antidromic Stimuli in the Sliced Hippocampal Formation

Abstract

ITO, K., MIYAKAWA, H. and KATO, H. The Long-Term Facilitation of Neuronal Activity Produced by Repeated Pairing of an Orthodromic Stimulus and Antidromic Stimuli in the Sliced Hippocampal Formation. Tohoku J. exp. Med., 1986, 150 (2), 229-230-Long-term facilitation in extracellulary recorded population spikes was demonstrated by repeated paired stimulation (RPS) in CAl neurons of the guinea pig hippocampal slices. Paired stimulation, consisting of a single orthodromic “test” stimulus and a train (5 pulses at 200Hz) of antidromic stimuli with an interstimulus interval (ISI) of 20, 500msec or 1sec was repeated every 5sec over a 250sec period. The amplitude of the population spike in response to the test stimulus increased gradually after RPS and reached a plateau level 30-50min after RPS. The plateau value was dependent on ISI; the shorter the ISI the greater the increase of responses. In contrast, no facilitation was observed when either the test stimulus or the antidromic stimuli were applied separately, without pairing.