Figure 4.
Dopamine transporter binding potential (BPND) in bilateral nucleus accumbens (NAc) has an indirect effect on reinforcement learning ability through resting-state functional connectivity of NAc with orbitofrontal cortex (OFC). Variables entered in the mediation model were: DAT BPND in bilateral NAc (DAT BPND measured with the DAT radiotracer [11C]altropane, residualized for age, z-scored), bilateral NAc resting-state functional connectivity (z-scored Fisher’s z-transformed correlation coefficients) extracted from OFC (FDR, P < 0.05), and reinforcement learning (z-scored change in response bias towards a frequently rewarded stimulus). Shown are standardized regression coefficients for each path in the model; the standardized regression coefficient between DAT BPND and reinforcement learning, controlling for NAc-OFC connectivity, is in parentheses; all statistical tests were 2-sided.