Quantifying the contribution of subject and group factors in brain activation

Abstract

Human behavior is known to be idiosyncratic, yet research in neuroscience typically assumes a universal brain-behavior relationship. Here we test this assumption by estimating the level of idiosyncrasy in individual brain-behavior maps obtained using human neuroimaging. We first show that task-based activation maps are both stable within an individual and similar across people. Critically, although behavior-based activation maps are also stable within an individual, they strongly diverge across people. A computational model that jointly generates brain activity and behavior explains these results and reveals that within-person factors have much larger effect than group factors in determining behavior-based activations. These findings demonstrate that unlike task-based activity that is mostly similar among people, the relation between brain activity and behavioral outcomes is largely idiosyncratic. Thus, contrary to popular assumptions, group-level behavior-based maps reveal relatively little about each individual.

Variance (un)explained: Experimental conditions and temporal dependencies explain similarly small proportions of reaction time variability in linear models of perceptual and cognitive tasks

“…Various neuropsychiatric diseases have already been associated with increased variability compared to healthy populations, such as ADHD (Kofler et al, 2013; Tamm et al, 2012), Alzheimer’s Disease (Tales et al, 2012; Tse et al, 2010), as well as schizophrenia, depression, and borderline disorder (Kaiser et al, 2008; also see Dinstein et al, 2013). Furthermore, recent work has suggested that neural activity associated with experimental factors is highly consistent across participants, but that neural activity associated with fluctuations in task performance has high inter-subject variability, but is stable within individuals over time (Nakuci et al, 2022). These findings suggest that neural fluctuations relating to performance could in itself be an individual trait, though their reliability over time and contexts remains an open question.…”

Multiple Brain Activation Patterns for the Same Perceptual Decision-Making Task

“…Our analysis utilized a dataset consisting of 50 healthy subjects (25 females; Mean age = 26; Age range = 19-40) that has been described elsewhere 46 . All subjects were screened for any history of neurological disorders or MRI contraindications.…”