Behavioral approach and orbitofrontal cortical activity during decision-making in substance dependence

Abstract

Behavioral approach, defined as behavior directed toward a reward or novel stimulus, when elevated, may increase one's vulnerability to substance use disorder. Behavioral approach has been associated with relatively greater left compared to right frontal activity; behavioral inhibition may be associated with relatively greater right compared to left frontal brain activity. We hypothesized that substance dependent individuals (SDI) would have higher behavioral approach than controls and greater prefrontal cortical activity during decision-making involving reward. We hypothesized that behavioral approach would correlate with left frontal activity during decision-making and that the correlation would be stronger in SDI than controls. 31 SDI and 21 controls completed the Behavioral Inhibition System/Behavioral Approach System (BIS/BAS) scales and performed a decision-making task during fMRI. Orbitofrontal (OFC) and dorsolateral prefrontal activity were correlated with BIS and BAS scores. Compared to controls, SDI had higher BAS Fun Seeking scores (p<0.001) and worse decision-making performance (p=0.004). BAS Fun Seeking correlated with left OFC activity during decision-making across group (r=0.444, p<0.003). The correlation did not differ by group. There was no correlation between BIS and right frontal activity. Left OFC may play a role in reward-related decision-making in substance use disorder especially in individuals with high behavioral approach.

Keywords: Behavioral approach; Behavioral inhibition; Bis/bas; Dorsolateral prefrontal cortex (DLPFC); Orbital frontal cortex (OFC); Substance dependence.

Figure 1

BOLD signal in SDI and controls during decision-making. SDI showed higher activity than controls in left OFC, **p<0.003, surviving Bonferroni correction for multiple comparisons. Images are in neurological convention. Graphs mean ± SEM

Figure 2

Left OFC activity correlated positively with BAS Fun Seeking across groups (r=0.444, p<0.003), surviving Bonferroni correction for multiple comparisons. SDI (solid gray circles), controls (open diamonds)