Ventral striatal activity was conspicuously absent, although there was a significant difference between odor classes within the VTA that did not differ between groups. Alcoholic drink cues activate the ventral striatum in some (e.g., Bragulat et al., 2008; Kareken et al., 2004; Myrick et al., 2004; Myrick et al., 2008), but not all alcohol cue exposure studies (e.g., George et al., 2001; Hermann et al., 2006; Park et al., 2007; Schneider et al., 2001; Tapert et al., 2004). The reasons are unclear, but there are some theoretical possibilities. First, unlike work in animals, human imaging studies of cue availability rarely include the possibility of contingently obtaining reward (alcohol) as a function of cue exposure— a facet which might dampen ventral striatal responses that encode any learned reward-cue association. In this vein, Bjork and Hommer (2007) showed that passively received monetary rewards did not provoke significant ventral striatal BOLD responses, whereas the anticipation of making an instrumental response to obtain money did— particularly if the reward contingency was uncertain. Similarly, Elliott et al. (2004) found that instrumental acts for rewards modulated
