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High‐frequency oscillation in the hippocampus of the behaving rat and its modulation by the histaminergic system
Author(s) -
Knoche A.,
Yokoyama H.,
Ponomarenko A.,
Frisch C.,
Huston J.,
Haas H.L.
Publication year - 2003
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.10057
Subject(s) - histaminergic , hippocampal formation , neuroscience , chemistry , inhibitory postsynaptic potential , hippocampus , histamine , psychology , endocrinology , biology
The histaminergic neurons located in the posterior hypothalamus modulate whole brain activity in a manner dependent on behavioral state. We have investigated their influence on high‐frequency oscillation (200‐Hz ripples) in the hippocampal CA1 region of freely moving rats. The occurrence of these ripples, assumed to be involved in memory trace formation, was markedly enhanced after injection of the H1‐antagonists pyrilamine and ketotifen in a lateral ventricle, indicating a tonic activity of the histaminergic system. The H2‐ and H3‐antagonists cimetidine and thioperamide were ineffective. We suggest a mediation of these effects through blocking the known histaminergic excitation of septal neurons. Histamine administered by the intracerebroventricular route had an inhibitory action on ripples. H1‐receptor activation, which has been shown to inhibit learning and memory, thus shifts hippocampal activity away from high‐frequency oscillation toward theta activity. Hippocampus 2003;13:273–280. © 2003 Wiley‐Liss, Inc.