ABSTRACT The reliance of fMRI research on between‐person comparisons is limited by low test–retest reliability and an inability to explain within‐person processes. Intraindividual studies are needed to understand how changes in brain functioning relate to changes in behavior. Here, we present open data and analysis of a novel intensively sampled fMRI study. This precision imaging dataset includes 44 sessions acquired across four participants at a twice‐weekly rate. In each session, participants completed multiple reward‐related tasks, mood and alertness ratings, and a behavioral mood manipulation. We examined how the reward response reflects between‐person or within‐person variance. Trial‐level models suggested dramatically more trials than typically collected are needed to maximize reliability within runs and individuals. Test‐retest reliability of the reward response was very low and not explained by measurement error, suggesting low power for between‐person comparisons without large amounts of data. At an intraindividual level, mood and alertness explained up to 37% of the intraindividual variance of the anticipatory reward response. Finally, we found that while reliability or brain‐behavior associations were not improved by multi‐echo denoising, a multivariate reward signature had stronger intraindividual behavioral associations than a univariate anatomical mask. Together, results suggest that the BOLD reward response is not a stable trait‐like marker, but moderated by state‐like factors. More broadly, BOLD activation to reward tasks—and likely other fMRI tasks—presents substantial opportunity for within‐person study to complement the traditional focus on between‐person study. We conclude with a discussion of considerations for intensive longitudinal neuroimaging designs.
Mattoni et al. (Tue,) studied this question.