“…Both families of receptors are highly expressed in brain areas implicated in instrumental learning and performance, including the striatum, prefrontal cortex, and amygdala (Goldberg et al, 2012;Leslie et al, 2013;Thiele, 2013). Acetylcholine is also known to be involved in regulating dopamine signaling (Cachope et al, 2012;Chapman et al, 1997;Di Giovanni and Shi, 2009;Threlfell et al, 2012), a neuromodulator that has been more directly implicated in motivated behavior and is known to underlie the response-invigorating influence of rewardpaired cues on reward-seeking behavior (Dickinson et al, 2000;Lex and Hauber, 2008;Ostlund and Maidment, 2012;Wassum et al, 2011Wassum et al, , 2013. While acetylcholine has been implicated in various aspects of reward-motivated behavior (Mendez et al, 2012;Pratt and Kelley, 2004;Ragozzino et al, 2009), much remains unknown about its specific contributions to action selection.…”