¹Laboratoire de Neurobiologie de la Cognition, CNRS UMR 6155, Aix-Marseille Université, Marseille, France

Correspondence: Dr C Baunez, Laboratoire de Neurobiologie de la Cognition, CNRS UMR 6155, Université de Provence, Case C, 3 place Victor Hugo, 13331 Marseille Cedex 3, France. Tel: +33 4 88 57 68 76; Fax: +33 4 88 57 68 72; E-mail: cbaunez@up.univ-mrs.fr

Received 16 October 2006; Accepted 22 March 2007; Published online 25 April 2007.

Abstract

In addition to its role in motor and attentional processes, the subthalamic nucleus (STN) has also been recently demonstrated to be involved in motivational function. Indeed, bilateral STN lesions modulate differentially the motivation for natural rewards and drugs of abuse, increasing motivation for food and decreasing motivation for cocaine in rats. Here, we show that in outbred rats, the STN can modulate the motivation for alcohol according to alcohol preference, without affecting alcohol intake. When performed on 'High-Drinker' rats, STN lesions enhanced the breaking point (BP) under a progressive ratio schedule of reinforcement and increased the time spent in the environment previously paired with alcohol access in the place preference paradigm. In contrast, when performed on 'Low-Drinker' rats, STN lesions decreased the BP and increased the time spent in the environment paired with water. These results show that STN lesions enhance the motivation for alcohol in rats showing a high alcohol preference, whereas they decrease it in rats showing a low preference for alcohol. These results suggest that the STN plays a complex role in the reward circuit, that is not limited to a dissociation between motivation for natural rewards and drugs of abuse, but takes other factors, such as alcohol preference, into account.