Table 1.
Demographic characteristics of marijuana (MJ) and control (CON) groups.
Table 2.
Peak loci of activation for anticipation of GAIN (vs. NEUTRAL) and LOSS (vs. NEUTRAL).
Figure 1.
Activation in Nucleus Accumbens during anticipation.
Mean z-scores per level of magnitude (Lo = $0.20, Med = $1.00, Hi = $5.00) for marijuana users (MJ) and controls (CON) for anticipation of GAIN and LOSS (relative to NEUTRAL) in the nucleus accumbens (NAc). Mean z-scores were extracted using an anatomical mask of the NAc based on the definition described in Filbey et al. (2008).
Figure 2.
Differences between positive and negative incentivization processes during the anticipation phase.
(A) Contrast of GAIN vs. LOSS and LOSS vs. GAIN during the anticipation phase in marijuana users and controls (cluster-corrected p<.05, z = 2.3); (B) Mean z-scores for marijuana users and controls during GAIN (vs. NEUTRAL) and LOSS (vs. NEUTRAL) in the orbitofrontal cortex (OFC), precuneus, and inferior frontal gyrus (IFG); (C) Contrast of positive and negative incentivization differences (GAIN vs. LOSS) between marijuana users and controls (cluster-corrected p<.05, z = 1.96). MJ = marijuana group; CON = control group.
Table 3.
Peak loci of activation differences for anticipation of LOSS vs. GAIN and_GAIN vs. LOSS.
Figure 3.
Distribution of Total Marijuana Checklist Scores.
The possible range of Marijuana Withdrawal Checklist (MWC) total score is 0–27, which are derived from 9 items scored using a 4-point Likert scale (0 = none, 1 = mild, 2 = moderate and 3 = severe).
Figure 4.
Negative correlations between marijuana withdrawal checklist (MWC) and anticipation of LOSS (vs. NEUTRAL) BOLD response in bilateral amygdala (shown below).
Significant at cluster-corrected p<.05, z = 1.96. For the scatterplots, an anatomical mask of the amygdala was created based on the definition described by Tzourio-Mazoyer and colleagues [64].
Table 4.
Peak loci of activation during correlation between total marijuana withdrawal checklist (MWC) scores and BOLD response during the anticipation phase.
Table 5.
Peak loci of activation during the outcome phase for GAIN (vs. NEUTRAL), LOSS (vs. NEUTRAL).