fMRI Reveals Differences Between Neural Systems Recruited for Time Perception in Children with and without Autism

Background:  There is a small, but growing number of empirical findings that suggest individuals with autism experience differences in timing and time perception, and it has been theoretically proposed that temporal processing deficits may contribute to characteristic features of autism. To-date these studies have included behavioral-cognitive assessments, and have not been extended into functional brain mapping. It is reasonably well established that typical individuals tend to recruit cortico-cerebellar circuits when actively timing relatively short durations (sub-second, e.g., <1-2 s) and cortico-striatal circuits when timing longer (supra-second, e.g., >3 s) durations (although this is not mutually exclusive). 

Objectives:  The current study sought to examine which brain regions children with autism recruit when making magnitude estimates of “time” (duration). 

Methods:  Children with and without a diagnosis of autistic disorder (8-13 years old) were scanned while performing a temporal ordinal comparison task; a standard duration (2 or 8 sec) was followed in quick succession by a comparison duration that was a deviant of the standard (± 12, 24 & 36%) and participants were required to judge whether the comparison was ‘shorter’ or ‘longer’ (than the standard). 

Results:  Group differences in regional activity were observed when children were timing both the standard and comparison durations. For instance, non-affected participants revealed greater activation in the cerebellum when timing the 2-s standard and the caudate-putamen when timing the 8-s standard (as expected); in contrast, children with autism recruited the caudate-putamen more heavily when timing the shorter standard (and not the longer one). 

Conclusions: These results lend support to existing behavioral evidence that individuals with autism may subjectively experience the passage of time differently. The implications of these results to our understanding of autistic symptomology will be outlined.