conditions; Paulson 2002) are combined under the general heading of brain activity (including fMRI and certain types of SPECT, PET, and autoradiography studies). Also, in order to build a cohesive model of brain activity responses to acute and chronic smoking, nicotine and cigarette studies will be reviewed together while recognizing that cigarette smoke has many constituents other than nicotine (Baker et al. 2004; Fowles and Dybing 2003).
