Test-retest reliability of event-related functional MRI in a probabilistic reversal learning task.

Repeated functional magnetic resonance imaging (fMRI) studies aim to detect changes in brain activity over time, e.g. to analyze the cerebral correlates of therapeutic interventions. This approach requires a high test-retest reliability of the measures used to rule out incidental findings. However, reliability studies, especially for cognitive tasks, are still difficult to find in the literature. In this study, 10 healthy adult subjects were scanned in two sessions, 16 weeks apart, while performing a probabilistic reversal learning task known to activate orbitofrontal-striatal circuitry. We quantified the reliability of brain activation by computing intra-class correlation coefficients. Group analysis revealed a high concordance for activation patterns in both measurements. Intra-class correlation coefficients (ICCs) were high for brain activation in the associated regions (dorsolateral prefrontal, anterior prefrontal/insular and cingulate cortices), often exceeding 0.8. We conclude that the probabilistic reversal learning task has a high test-retest reliability, making it suitable as a tool for evaluating the dynamics of deterioration in orbitofrontal-striatal circuitry, e.g. to illustrate the course of a psychiatric disorder.