Selective lesions of the dorsomedial striatum impair serial spatial reversal learning in rats

• Published in: Behavioural brain research Vol. 210; no. 1; pp. 74 - 83
• Main Authors: Castañé, Anna, Theobald, David E.H., Robbins, Trevor W.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 26.06.2010; Elsevier; Elsevier/North-Holland Biomedical Press
• Subjects: Animals; Behavioral psychophysiology; Behavioural flexibility; Biological and medical sciences; Callithrix; Corpus Striatum - drug effects; Corpus Striatum - injuries; Corpus Striatum - physiology; Discrimination; Discrimination, Psychological - physiology; Eating - physiology; Excitotoxic lesion; Extinction, Psychological - physiology; Fundamental and applied biological sciences. Psychology; Ibotenic Acid - toxicity; Learning; Male; Memory - physiology; Motor Activity - physiology; Neuropsychological Tests; Neurotoxins - toxicity; Nucleus accumbens; Nucleus Accumbens - drug effects; Nucleus Accumbens - injuries; Nucleus Accumbens - physiology; Perseveration; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Quinolinic Acid - toxicity; Rats; Research Report; Reversal Learning - physiology; Space Perception - physiology; Spatial reversal learning; Striatum; Time Factors; Excitotoxic lesion; Learning; Nucleus accumbens; Striatum; Perseveration; Discrimination; Behavioural flexibility; Spatial reversal learning; Rat; Rodentia; Central nervous system; Basal ganglion; Corpus striatum; Space perception; Encephalon; Vertebrata; Mammalia; Acquisition process; Reversal learning; Serial learning; Animal; Behavior; Lesion; Perceptive learning
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/j.bbr.2010.02.017

Impairments in reversal learning have been attributed to orbitofrontal cortex (OFC) dysfunction in many species. However, the role of subcortical areas interconnected with the OFC such as the striatum remains poorly understood. This study directly evaluated the contribution of core and shell sub-regions of the nucleus accumbens (NAc), dorsomedial (DMS) and dorsolateral (DLS) striatum to reversal learning of an instrumental two-lever spatial discrimination task in rats. Selective NAc core, DMS and DLS lesions were achieved with microinjections of quinolinic acid and NAc shell lesions with ibotenic acid. Damage to NAc core or shell did not affect retention of a previously acquired instrumental spatial discrimination. In contrast, DLS and DMS lesions produced changes in aspects of discrimination performance such as the latency to collect earned food pellets. Neither NAc core or shell lesions nor DLS lesions affected the main indices of reversal performance. Conversely, DMS lesion rats showed a significant impairment in reversal learning. DMS damage increased the number of errors to reach criteria that were perseverative in nature. The deficit in reversal learning in DMS lesion rats was not associated with an impairment to extinguish instrumental responding. There were no effects on spontaneous locomotor activity. Our data are in agreement with recent work showing that lesions of the medial striatum in marmoset monkeys produce perseverative impairments during a serial visual discrimination reversal task and support the hypothesis that dorsomedial striatal dysfunction contributes to pathological perseveration, which is a common feature of many psychiatric disorders.