Retrosplenial cortex lesions impair acquisition of active avoidance while sparing fear-based emotional memory.

Full Abstract

There is strong evidence that the rat retrosplenial cortex (RC) is implicated in spatial navigation and in learning of both aversive and reward-based discrimination tasks. However, its involvement in other functions subserved by the limbic system to which it belongs has not yet been documented. We compared the performance of rats with bilateral excitotoxic damage to RC with that of control rats in a battery of conventional tests, including an open field, plus maze, fear conditioning, step-through passive avoidance, and two-way active avoidance techniques. In the open field, RC-lesioned rats showed somewhat decreased locomotion in the inner zone and increased defecation, which is suggestive of an anxiogenic effect. However, no differences between groups were detected in the plus-maze and inhibitory avoidance tests. Freezing scores recorded during fear conditioning, as well as during the context and tone tests, which were performed, respectively, 24 and 48 h after conditioning, did not differ between the groups. In contrast, acquisition of the active avoidance response was significantly impaired in rats with damaged RC, regarding both response latency and correctness. These data suggest that although the rat RC may play a role in the regulation of emotional responsiveness to new situations, it does not appear to contribute to emotional memory. They are also consistent with the idea that RC is a part of the limbic system that is involved in the compilation of motor programs for complex stereotyped movements such as approach and avoidance.

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Author information

Author/s: Lukoyanov, Nikolai V (NV); Lukoyanova, Elena A (EA);

Affiliation: Department of Anatomy, Porto Medical School, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal. luk(-atsign-)med.up.pt

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-Oct; vol 173 (issue 2) : pp 229-36

Dates: Created 2006/09/01; Completed 2006/11/01; Revised 2006/11/15;

PMID: 16876887, 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.

Analysis of Variance
Animals
Avoidance Learning - physiology
Behavior, Animal
Brain Injuries - chemically induced; pathology
Conditioning (Psychology) - physiology
Exploratory Behavior - physiology
Fear
Freezing Reaction, Cataleptic - physiology

Gyrus Cinguli - injuries; physiopathology
Male
Maze Learning - physiology
Memory - physiology
N-Methylaspartate
Rats
Rats, Wistar
Reaction Time - physiology
Time Factors

Associated Chemicals: N-Methylaspartate (6384-92-5)

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