| Authors | Subjects | Method | Intervention | Results | 
      
        | a)    Animal Studies |  |  |  |  | 
      
        | Marenco et al. [156] | Rats-    chronically nic exposed vs. nic naive | 2-deoxy-D-[1-14C] glucose autoradiography | SC nic (0.4 mg/kg) vs. saline
 | ↑ thal, superior colliculus in chronically exposed;  thal, superior colliculus, medial    habenula and dorsal lateral geniculate in nic naive | 
      
        | London et al. [38, 39] | Rats | 2-deoxy-D-[1-14C]glucose autoradiography | SC nic (0.1 to 1.75 mg/kg)
 | ↑    nicotine rich regions, including thal, cereb, visual system, others | 
      
        | b)    Human Studies |  |  |  |  | 
      
        | Staley et al. [86]
 | 16 smokers 16 non-smokers
 | 5    IA-SPECT | Recent    abstinence | ↑    Striatum, Parietal cortex, frontal cortex, anterior cingulated, temporal    cortex, occipital cortex, cerebellum | 
      
        | Zubieta et al. [43] | 19 smokers | 15O-PET | Nicotine    containing versus denicotinized cigarettes | ↓ global blood flow | 
      
        | Stapleton et al. [27] | 4 smokers; 2 non-smokers | 2 FDG-PETs (Fully quantified)
 | IV    nic (1.5 mg) versus placebo | ↓global and most regions studied | 
      
        | Yamamoto et al. [25] | 10    smokers | 99mTc-ECD SPECT | Cigarette    vs. abstinence | ↓global blood flow | 
      
        | Rose et al. [35] | 34    smokers | 15O-PET | Cigarette    vs. no nic control conditions | ↑L frontal factor (incl prefrontal and ACC),↓ L amyg rCBF | 
      
        | Zubieta et al. [40] | 18    smokers | 15O-PET | Nic    nasal spray vs. pepper spray | ↑anterior thal; ↓ L    ant temp and R amyg | 
      
        | Domino et al. [26] | 11    smokers | FDG-PET | Nic nasal spray vs. pepper spray | Small    ↓ global; ↑    L IFG, L PC, R thal, visual cortex; ↓    normalized L ins and R inf occ ctx | 
      
        | Domino et al. [37] | 18    smokers | 15O-PET | Nic nasal spray vs. pepper spray | ↑ thal,    pons, visual cortex, cereb | 
      
        | Stein et al. [36] | 16    smokers | fMRI | IV    nic (0.75- 2.25 mg/70 kg wt) vs. placebo
 | ↑ R NAc and bilateral amyg, cingulate, frontal    lobes, thal, others | 
      
        | Rourke et al. [28] | 8    smokers; 8 former smokers; 17 non-smokers | iodine-123    iodoamphetamine (IMP) SPECT | Smokers    smoked the morning of the scan; other groups did not | ↓    cortical uptake of IMP (a measure of blood flow) in current smokers compared    to other groups
 |