We thank members of the Action Lab for fruitful discussions. Finally,

we thank three anonymous reviewers of a previous version of this manuscript for their thoughtful comments and suggestions. “
“Cortical projections to the striatum form the front end of the cortical-basal ganglia-thalamo-cortical loops. The PLX4032 anatomy of these networks (Alexander et al., 1986, Haber et al., 2006, Middleton and Strick, 2000, Parent and Hazrati, 1995 and Parthasarathy et al., 1992) and the physiology of single neuron responses in areas of frontal cortex (Averbeck and Lee, 2007, Funahashi et al., 1991, Fuster, 2008, Histed et al., 2009, Miller and Cohen, 2001 and Pasupathy and Miller, 2005) and the striatum (Apicella et al., 2011, Barnes et al., 2005, Hollerman et al., 1998, Jin et al., 2009, Lauwereyns et al., 2002a, Lauwereyns et al., 2002b and Simmons et al., 2007) have been extensively studied. Yet the contributions of these networks to normal behavior are still unclear. There are numerous hypotheses, mostly specifying the striatal transformation of cortical inputs, including dimensionality reduction (Bar-Gad et al., 2003), reinforcement learning (Dayan and Daw, 2008, Doya, 2000,

Frank, 2005 and Parush et al., 2011), habit formation (Graybiel, 2008), motor learning (Doyon et al., 2009), sequential motor control (Berns and Sejnowski, 1998, Marsden and Obeso, 1994 and Matsumoto et al., 1999), response vigor (Turner and Desmurget, 2010), action selection (Denny-Brown and Yanagisawa, crotamiton 1976, Grillner et al., 2005, Hazy et al., 2007, Houk et al., 2007, Humphries et al., 2006, Kamali Sarvestani et al., 2011, Mink, selleck compound 1996, Redgrave et al., 1999 and Rubchinsky et al., 2003), execution of well-learned, automated motor plans (Marsden, 1982), and the trade-off between habitual and goal-directed or cognitive action planning (Daw et al., 2005), also conceptualized as a trade-off between attention demanding cognitive and automatically

executed actions (Norman and Shallice, 1986). The action selection hypothesis, first proposed on the basis of monkey striatal lesion data (Denny-Brown and Yanagisawa, 1976), suggests that the cortex generates ensembles of possible actions and the striatum selects from among these actions (Houk et al., 2007, Humphries et al., 2006 and Mink, 1996). The action selected by the striatum, via the rest of the basal ganglia (BG) circuitry, disinhibits the thalamo-cortical and brainstem networks that lead to execution of the selected action and inhibits the networks that represent competing actions. Many experimental studies and models also suggest that the striatum is important for reinforcement learning (RL) or learning from feedback (Amemori et al., 2011, Daw et al., 2011, Frank et al., 2004, Histed et al., 2009, Kamali Sarvestani et al., 2011, O’Doherty et al., 2004, Pasupathy and Miller, 2005 and Samejima et al.