How Do Children with and without Autism Perceive the Passage of Time?: fMRI Reveals Differences in Neural Systems Recruited for Time Perception
Objectives: To-date, there are no existing fMRI studies of interval timing in typical childhood, or in those children affected with autism. In our fMRI study, children (aged 8-13 years) with and without a diagnosis of autism completed a temporal ordinal comparison (time perception) procedure inside the magnet using supra-second durations ranging from 1-11-s.
Methods: During each trial in the temporal ordinal comparison procedure, a pair of stimulus durations (comprising a standard, S; and comparison, C) are presented in quick succession, and children were asked to judge whether C was ‘shorter’ or ‘longer’ than S. There were two versions of the task in which S was either (consistently) 2.2-s or 8.2-s. In both versions, the six C durations were shorter and longer incremental deviants of S (+/-12, 24, 36%). Our a-priori ROI mask included regions typically recruited during adult time perception tasks: the supplementary motor area; the middle frontal and pre-frontal, superior and inferior parietal, and middle and superior temporal gyri; sub-lobar regions (e.g., striatum, thalamus, insula) and cerebellum.
Results: Data revealing group patterns and differences in neural activation during both S and C durations will be presented across our ROI. One particularly interesting group difference we observed corresponds to the apparent over-engagement of striatal timing mechanisms when those with autism are timing relatively shorter S and C durations—for instance unlike unaffected children, they revealed striatal activity during the 2.2-s but not 8.2-s standard duration; and tended to recruit the striatum across the comparison durations in the 2.2-s version of the task (ranging between 1-3-s).
Conclusions: Children with autism show different patterns of activity in several brain regions known to be involved in temporal processing (compared to unaffected children), particularly cortico-striatal systems which are recruited (or ‘engaged’) at shorter durations than appears typical. This pattern suggests affected individuals may experience a subjective lengthening of relatively short durations, and/or, a proclivity to engage beat-based timing mechanisms.