Reduced behavioral and neural activation in stimulant users to different error rates during decision making

Abstract

Background: Behavioral processes and neural systems dysfunctions that put individuals at risk for drug use in general, and stimulant use in particular, are poorly understood. Here, the hypothesis is examined that stimulant-using subjects adjust their decision making less as a function of errors as evidenced by attenuated behavioral and neural substrate activation patterns.

Methods: Twelve young adults who had used stimulants were compared with 12 education-matched, stimulant-naive comparison subjects. Subjects completed the two-choice prediction task with three fixed error-rate conditions (20%, 50%, or 80% errors) during functional magnetic resonance imaging.

Results: Stimulant users relative to comparison subjects showed less strategy adjustment to different error rates, for example, they were less likely to stay with winning responses (win-stay) and to shift away from losing responses (lose-shift). These subjects also showed different activation patterns as a function of error rate in left insular and bilateral dorsolateral prefrontal cortex but not anterior cingulate. The degree to which individuals adjusted switching rate, or win-stay/lose-shift consistent responses, as a function of errors was correlated with the difference in insular cortex activation differences between high and low error rates.

Conclusions: The behavior of stimulant users is less adaptive to the frequency of errors made and fewer brain processing resources are deployed during decision making to anticipate erroneous performance. These findings could be markers for the predisposition of drug taking; however, their relevance for development of drug dependence requires further study.

Figure 1. Behavioral Differences during Two-choice Prediction Task

Stimulant using individuals relative to comparison subjects showed a reduced influence of the prior stimulus (car) on their decision-making irrespective of error-rate condition (upper left) and adjust both switching behavior (lower left) and win-stay/lose-shift consistent responses less as a function of error rate (lower right), but did not differ on response latency (upper right).

Figure 2. Different Activation to Error rate

Stimulant using individuals show an inverse relationship between error rate and brain activation in left insula (upper right) and bilateral middle frontal gyrus (lower left and right).

Figure 3. Brain Behavior Relationships

Greater reduction of win-stay lose-shift mutual information (WSMI) as a function of error rate (fraction of errors: 0.8 – 0.2) was associated with greater attenuation of insular cortex activation as a function of error rate (left). Individuals with higher experience seeking scores adjusted right middle frontal gyrus less as a function of error rate (right). Both results were independent of stimulant or cannabinoid use.