Behavioural Brain Research 100 (1999) 5 – 14 Research report Effects of medial and lateral caudate-putamen lesions on place- and cue-guided behaviors in the water maze: relation to thigmotaxis B.D. Devan a , R.J. McDonald b , N.M. White c, * a Laboratory of Neuropsychology, National Institute of Mental Health, Bluilding 49, Room 1B80, Bethesda, MD 20892, USA b Department of Psychology, Uniersity of Toronto, 100 St. George St., Toronto ON, M5S 1A1, Canada c Department of Psychology, McGill Uniersity, 1205 Dr. Penfield Ae. Montreal, Quebec, H3A 1B1, Canada Received 27 April 1998; received in revised form 6 July 1998; accepted 6 July 1998 Abstract Rats with dorsomedial or dorsolateral caudate-putamen lesions and sham-operated controls were trained on the standard hidden platform (place) task in the water maze. Compared to controls, rats with dorsomedial, but not dorsolateral lesions were slower to escape to the hidden platform and spent significantly more time swimming near the wall of the pool (thigmotaxis) on the early trials, but eventually achieved control levels of performance. When the platform was removed from the pool, all groups exhibited a significant bias for swimming in the training quadrant and crossing the former location of the platform. In the second phase of the experiment rats were given visible platform (cue) training in a different room/pool with the platform moved to a new location each day. Rats with dorsomedial, but not dorsolateral lesions required more trials to reach criterion; again, thigmotaxis was observed on the early trials. The third phase, carried out in the original room/pool, included a place-retention trial followed by a place-cue competition test, (i.e. a choice between the learned spatial location of the hidden platform and the visible platform in a new location). The rats with dorsomedial, but not dorsolateral lesions swam to the visible platform more frequently than the controls. In the final phase, the rats in both lesion groups exhibited slightly lower thigmotactic tendencies than controls in a standard dry-land open field, a finding inconsistent with the hypothesis that thigmotaxis in the water maze is due to increased fear or anxiety. Taken together with other behavioral and anatomical findings, the results suggest that the dorsomedial caudate-puta- men, by virtue of its connections with limbic and prefrontal cortical regions, may mediate a response selection process that integrates cognitive information with stimulus-response tendencies. © 1999 Elsevier Science B.V. All rights reserved. Keywords: Dorsal striatum; Medial caudate-putamen; Lateral caudate-putamen; Water maze; Place navigation; Cue navigation; Competition; Thigmotaxis; Rat 1. Introduction Early lesion studies with cats and monkeys [15,20,60] led Divac [16,17] and Rosvold [58,59] to propose het- erogeneous functions for different corticostriatal sys- tems. More recent investigations with rats have also shown behavioral dissociations with regionally selective lesions of dorsal striatum (or caudate-putamen: CPu) [19,23 – 25,28,34,35,39,55,56,71,78]. In general, lesions of the lateral CPu disrupt sensorimotor function and simple stimulus-response learning [23,24,56,71,75,76], whereas lesions of the medial CPu often produce im- pairments on allocentric spatial tasks [11,14,74]. Rats with medial CPu lesions are impaired at acquir- ing both the hidden and visible platform versions of the Morris [52] water maze task [14,74]. However, it is not clear whether such deficits are due to a disruption of learning or to some other effect on motivational, mo- toric or sensory processes. Some researchers have ob- * Corresponding author. Tel.: +1 514 3986082; fax: +1 514 3984896; e-mail: nwhite@psych.mcgill.ca 0166-4328/99/$ - see front matter © 1999 Elsevier Science B.V. All rights reserved. PII S0166-4328(98)00107-7