Test-retest reliability of a finger-tapping fMRI task in a healthy population.

Measuring brain activity during fMRI tasks is one of the main tools to identify brain biomarkers of disease or neural substrates associated with specific symptoms. However, identifying correct biomarkers relies on reliable measures. Recently, poor reliability was reported for task-based fMRI measures. The present study aimed to demonstrate the reliability of a finger-tapping fMRI-task across two sessions in healthy participants. Thirty-one right-handed healthy participants aged 18-60 took part in two MRI sessions three weeks apart during which we acquired finger-tapping task-fMRI. We examined the overlap of activations between sessions using Dice-Similarity-Coefficients, assessing their location and extent. Then, we compared amplitudes calculating Intraclass-Correlation-Coefficients (ICC) in three sets of Regions-of-Interest (ROIs) in the motor-network: Literature-based ROIs (10mm-radius spheres centered on peaks of an activation-likelihood-estimation), anatomical ROIs (regions as defined in an atlas), and ROIs based on conjunction analyses (super-threshold voxels in both sessions). Finger-tapping consistently activated expected regions, e.g. left primary sensorimotor cortices, premotor area, and right cerebellum. We found good-to-excellent overlap of activations for most contrasts (Dice-coefficients .54-.82). Across time, ICCs showed large variability in all ROI-sets (.04-.91). However, ICCs in most ROIs indicated fair-to-good reliability (mean=.52). The least specific contrast consistently yielded the best reliability. Overall, the finger-tapping task showed good spatial overlap and fair reliability of amplitudes on group-level. While caution is warranted interpreting correlations of activations with other variables, identification of activated regions in response to a task and their between-group comparisons are still valid and important modes of analysis in neuroimaging to find population tendencies and differences