Double dissociation between hippocampal and prefrontal lesions on an operant delayed matching task and a water maze reference memory task.

Full Abstract

The hippocampus and prefrontal cortex have both been implicated in various aspects of the acquisition, retention and performance of delayed matching to position (DMTP) tasks in the rat, although their precise respective contributions remain unclear. In the present study, rats were trained preoperatively on DMTP before receiving excitotoxic bilateral lesions of either the entire hippocampus or the medial prefrontal cortex. Rats with lesions of the prefrontal cortex exhibited a significant delay-dependent impairment on retention of the DMTP task, whereas hippocampal lesions were without effect. Rats were also exposed to a switch in the contingencies to a 'non-matching' rule, as an analogue of switching between decision rules in the human Wisconsin Card Sorting Test, in which human patients with prefrontal damage are impaired. Both lesion groups acquired the new contingency at control levels, providing no evidence towards a role for either of these areas in this type of rule-switching. The same rats were also assessed in a spatial reference memory task in the water maze, which revealed an impairment in escape latencies and path length that was specific to the hippocampal lesions. The results corroborate previous evidence that the hippocampus is not necessary for at least some aspects of working memory performance in the DMTP task, whereas the delay-dependent deficit in the prefrontal lesion group support this task as a potentially powerful tool for assessing the cognitive changes associated with frontal damage and repair.

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Author information

Author/s: Sloan, Hazel L (HL); Good, Mark (M); Dunnett, Stephen B (SB);

Affiliation: Brain Repair Group, School of Biosciences, Cardiff University, Wales, UK.

Journal and publication information

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

Journal: Behavioural brain research (Behav Brain Res), published in Netherlands. (Language: eng)

Reference: 2006-Jul; vol 171 (issue 1) : pp 116-26

Dates: Created 2006/05/23; Completed 2006/08/03; Revised 2006/11/15;

PMID: 16677723, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals
Conditioning, Operant - physiology
Discrimination Learning - physiology
Hippocampus - physiology
Male
Maze Learning - physiology
Memory - physiology

Memory - physiology
Pattern Recognition, Physiological - physiology
Prefrontal Cortex - physiology
Rats
Rats, Inbred Strains
Space Perception - physiology
Time Perception - physiology

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