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Hippocampal activity, but not plasticity, is required for early consolidation of fear conditioning with a short trace interval
Author(s) -
Burman Michael A.,
Gewirtz Jonathan C.
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2007.05493.x
Subject(s) - fear conditioning , neuroscience , memory consolidation , nbqx , psychology , conditioning , classical conditioning , hippocampus , engram , antagonist , ampa receptor , nmda receptor , amygdala , medicine , receptor , statistics , mathematics
The dorsal hippocampus is required for explicit cue fear conditioning only when a temporal gap is inserted between conditioned stimulus (CS) termination and unconditioned stimulus (US) onset (trace fear conditioning). To examine the role of the dorsal hippocampus in associating temporally discontiguous stimuli and to minimize the potential contribution of contextual cues, fear conditioning was conducted using a relatively short (3‐s) trace interval. Inactivation of the dorsal hippocampus using the AMPA receptor antagonist NBQX (3 µg/hemisphere) or the GABA A agonist muscimol (5 µg/hemisphere) disrupted trace fear conditioning when conducted immediately following training. Trace conditioning was not disrupted significantly when NBQX was infused either before or 2 h after training. Similarly, NBQX infusions were not effective when the CS and US overlapped (delay conditioning). Moreover, trace conditioning was not impaired by intrahippocampal infusion of either the NMDA receptor antagonist AP5 (5 µg/hemisphere) or the L‐type voltage‐gated calcium channel (VGCC) blocker diltiazem (20 or 40 µg/hemisphere). These data suggest that the involvement of the dorsal hippocampus in short trace interval fear conditioning is largely restricted to the early period of memory consolidation, during which time it mediates the storage of long‐term memory in other brain regions.