Cholinergic modulation of trace conditioning trained in serial compound: A developmental analysis.

Full Abstract

In four experiments the effects of serial compound conditioning on responding to a trace-conditioned CS were evaluated using a fear conditioning paradigm. The subjects were 18- and 25-day-old Sprague-Dawley rats, previously shown to exhibit little or no trace fear conditioning. Here, animals as young as 18 days of age were shown to be capable of trace conditioning between a visual CS1 and a shock US, provided the trace interval was filled with a non-target CS2 during serial conditioning trials (CS1-->CS2-->US). To explore cholinergic mechanisms involved in trace and serial conditioning, additional experiments assessed conditioned responding following pre-training administration of the muscarinic receptor antagonist scopolamine. Scopolamine produced a dose-dependent reduction in responding to the trace CS1, regardless of whether subjects were trained with standard trace (CS1-->trace interval-->US) or serial (CS1-->CS2-->US) trials. Responding to CS2 was unaffected by scopolamine. These data suggest that central cholinergic systems are functional in the young animals, but are not normally sufficiently activated by standard trace conditioning procedures. The results suggest that serial compound conditioning can promote trace conditioning in young rats, as it does in adults, perhaps by enhancing cholinergic activity during training. Implications for the late ontogenetic emergence of trace conditioning as it relates to maturation of neural pathways and their role in the potentiating effects of a gap filler are discussed.

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Author information

Author/s: Hunt, Pamela S (PS); Barnet, Robert C (RC); Shea, Meghan E (ME); Baker, Eric M (EM);

Affiliation: Department of Psychology, College of William and Mary, PO Box 8795, Williamsburg, VA 23187-8795, USA. pshunt(-atsign-)wm.edu

Grants: AA015343 (Agency:NIAAA NIH HHS) ; AA12466 (Agency:NIAAA NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Neurobiology of learning and memory (Neurobiol Learn Mem), published in United States. (Language: eng)

Reference: 2006-Nov; vol 86 (issue 3) : pp 311-21

Dates: Created 2006/10/02; Completed 2006/12/07; Revised 2007/11/14;

PMID: 16774840, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Age Factors
Animals
Association Learning - drug effects; physiology
Avoidance Learning - drug effects; physiology
Brain - growth & development; physiology
Cholinergic Fibers - drug effects; physiology
Conditioning, Classical - drug effects; physiology
Dose-Response Relationship, Drug

Drug Administration Schedule
Fear - drug effects; physiology
Muscarinic Antagonists - administration & dosage
Random Allocation
Rats
Rats, Sprague-Dawley
Scopolamine - administration & dosage
Serial Learning - drug effects; physiology

Associated Chemicals: Muscarinic Antagonists (0) ; Scopolamine (51-34-3)

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