Catecholaminergic depletion in nucleus accumbens enhances trace conditioning

Nelson, Andrew J.D. and Thur, Karen E. and Spicer, C. and Marsden, C.A. and Cassaday, Helen J. (2011) Catecholaminergic depletion in nucleus accumbens enhances trace conditioning. Advances in Medical Sciences, 56 (1). pp. 71-79. ISSN 1896-1126

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Purpose: To examine the effect of dopamine depletion in nucleus accumbens on trace conditioning; to distinguish the role of core and shell sub-regions, as far as possible. Material/Methods: 6-hydroxydopamine was used to lesion dopamine terminals within the core and shell accumbens. Experiment 1 assessed conditioning to a tone conditioned stimulus that had previously been paired with footshock (unconditioned stimulus) at a 30s trace interval. Experiment 2 subsequently assessed contiguous conditioning (at 0s trace) using a light conditioned stimulus directly followed by the unconditioned stimulus.

Results: Both sham and shell-lesioned animals showed the normal trace effect of reduced conditioning to the trace conditioned stimulus but 6-hydroxydopamine injections targeted on the core subregion of the nucleus accumbens abolished this effect and enhanced conditioning to the trace conditioned stimulus. However, the depletion produced by this lesion placement extended to the shell. In Experiment 2 (at 0s trace), there was no effect of either lesion placement as all animals showed comparable levels of conditioning to the light conditioned stimulus. Neurochemical analysis across core, shell and comparison regions showed some effects on noradrenalin as well as dopamine.

Conclusions: The pattern of changes in noradrenalin did not systematically relate to the observed behavioural changes after core injections. The pattern of changes in dopamine suggested that depletion in core mediated the increased conditioning to the trace conditioned stimulus seen in the present study. However, the comparison depletion restricted to the shell subregion was less substantial, and a role for secondarily affected brain regions cannot be excluded.

Item Type: Article
Keywords: conditioned emotional response; associative learning; 6-hydroxydopamine
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Psychology
Identification Number:
Depositing User: Chamberlain, Mr Dick
Date Deposited: 28 May 2014 14:26
Last Modified: 17 Sep 2016 01:20

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