First, the signals related to the difference between the temporally discounted values for the two alternative targets,

which reliably predicts the animal’s choice, were more robust and found more frequently in the dorsal striatum. Second, the signals related to the direction of the animal’s eye movement during intertemporal choice were found only in the dorsal striatum. Therefore, the dorsal Sunitinib in vivo striatum is likely to play a more important role in choosing a particular action based on temporally discounted values than the ventral striatum. Previous single-neuron recording studies in the primate striatum have also shown that signals related to specific movements are largely confined to the dorsal striatum, including the caudate nucleus and putamen, whereas reward-related signals tend to be distributed evenly across different subdivisions of the striatum (Apicella et al., 1991, Schultz et al., 1992, Williams et al., 1993, Bowman et al., 1996, Hassani et al., 2001, Cromwell and Schultz, 2003, Kawagoe et al., 1998, Ding and Hikosaka, 2006 and Kobayashi et al., 2007). In some of these studies, the position of the target associated with a large reward was fixed for a block of trials during an instructed delay task, while the direction of the required movement was selected

randomly (Kawagoe et al., 1998, Ding and Hikosaka, 2006 and Kobayashi et al., 2007). These studies have found that some neurons in the caudate nucleus change their activity according to the position of the target associated DAPT with a large reward. In reinforcement learning theory, the value of reward expected from a particular action is referred to as action values (Sutton and Barto, 1998), and could be used to select an action to maximize reward intake. Indeed, it has been shown

that during a free-choice task, some neurons in the dorsal striatum change their activity according to the action values of specific movements (Samejima et al., 2005, Lau and Glimcher, Cytidine deaminase 2008 and Kim et al., 2009b). These results suggest that the dorsal striatum might play an important role in selecting an action with the most desirable outcomes, when the likelihood of reward from each action needs to be estimated from experience (O’Doherty et al., 2004, Tricomi et al., 2004 and Kimchi and Laubach, 2009). The results from the present study show that the dorsal striatum might also contribute to intertemporal choice by encoding the difference in the temporally discounted values for alternative outcomes. In addition, neurons in both CD and VS encoded the sum of the temporally discounted values with a time course similar to their difference, suggesting that the signals related to the temporally discounted values of the two targets were combined heterogeneously across different striatal neurons, similar to the activity related to action values in the posterior parietal cortex (Seo et al., 2009).