Brain idiosyncrasy during biological-motion perception is amplified in autistic individuals with intellectual impairment
摘要
Neuroimaging research in autism spectrum condition (ASC) often overlooks brain idiosyncrasy by focusing on group averages and frequently excludes individuals with co-occurring intellectual impairment (II).
MethodsWe investigated functional MRI correlates of passive biological motion (BM) perception, comparing typically developing controls (TDC; n = 33), autistic individuals without II (intellectually able; ASC-IA; n = 28), and autistic individuals with II (ASC-II; n = 19; defined by IQ or adaptive function < 85).
ResultsWhile standard group-average analyses revealed the expected BM-sensitive regions (e.g., bilateral posterior superior temporal sulci, cuneus) in the TDC and ASC-IA groups, the ASC-II group showed no consistent group-level activation pattern and exhibited greater activation in the right intraparietal sulcus compared to the ASC-IA group. Using a correlational distance-based metric, we quantified brain idiosyncrasy (“whole-sample brain variability”, VariabilityWhole), representing the deviance of an individual's activation pattern from others. Brain activity in the ASC-II group was significantly more idiosyncratic than the ASC-IA and TDC groups. Furthermore, VariabilityWhole showed significant transdiagnostic correlations with multiple cognitive and behavioural domains relevant to autism, including social difficulties, repetitive behaviours, non-verbal IQ, executive function, sensory hyper/hyposensitivity, ADHD symptoms, and adaptive function.
ConclusionsKey limitations include the cross-sectional design and the use of a passive viewing task without a concurrent behavioral measure to directly link brain findings to task performance. These findings highlight substantial brain heterogeneity within the autism spectrum, particularly in the understudied ASC-II subgroup, and suggest that individual differences in brain processing patterns, rather than solely group-average differences, are critically linked to clinical and cognitive phenotypes.