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Cholinergic modulation of Pavlovian fear conditioning: Effects of intrahippocampal scopolamine infusion
Author(s) -
Gale Greg D.,
Anagnostaras Stephan G.,
Fanselow Michael S.
Publication year - 2001
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.1051
Subject(s) - psychology , fear conditioning , cholinergic , neuroscience , classical conditioning , conditioning , hippocampus , context (archaeology) , freezing behavior , scopolamine hydrobromide , amygdala , anesthesia , medicine , muscarinic acetylcholine receptor , paleontology , statistics , mathematics , biology , receptor
Abstract Cholinergic neurotransmission has been implicated in the acquisition of a variety of tasks, including Pavlovian fear conditioning. To more precisely define the role of cholinergic modulation in this process, the effect of site‐specific cholinergic antagonism was assessed. Male Long‐Evans rats were implanted with chronic, bilateral cannulae aimed at the dorsal hippocampus. Infusions of scopolamine hydrobromide (50 μg bilaterally) or phosphate‐buffered saline (PBS) were made immediately prior to a signaled Pavlovian fear conditioning procedure. On consecutive days following training, all rats were given independent tests assessing freezing to both the training context and the tone conditional stimulus (CS). Relative to PBS infused controls, rats that received intrahippocampal infusions of scopolamine showed a significant attenuation of contextual freezing but comparable levels of freezing to the tone CS. Neither shock sensitivity nor general activity levels differed between rats infused with scopolamine or PBS. These findings suggest that fear conditioning to context, but not discrete CS, requires intact cholinergic neurotransmission in the hippocampus. Hippocampus 2001;11:371–376. © 2001 Wiley‐Liss, Inc.