Erforschung zeitlicher Aspekte sensorischer Wahrnehmung bei Autismus unter Verwendung von bildgebenden Verfahren und psychophysikalisch-experimenteller Untersuchungen
Final Report Abstract
The aim of the project was to highlight the pattern of abnormal timing functions in ASD, relate it to symptom severity, and delineate it from timing abnormalities in other developmental disorders. Events in the world unfold in time, and one challenge the brain must face is the recovery of event information in time. Temporal properties include episodic features such as when an event happened, for how long (i.e. interval timing), and the relationship to other events close in time. Hence, temporal integration is fundamental for human perception. At the outset of the project there were only a few studies suggesting that temporal processing is impaired in autism. It has also been discussed whether temporal binding, i.e. the tendency of neurons to synchronise their firing rate in order to integrate coded information, is impaired in autism. Based on this previous literature and suggestions of a ‘temporal neglect’ in autism I aimed at investigating whether the early perceptual abnormalities observed in autism may be related to a fundamental difference in the timing of early neuronal processing. There is now increasing evidence that temporal processing is impaired in ASD as well as in other developmental disorders such as dyslexia and ADHD. Our results indicate that individuals with ASD show a superior resolution of events in time, impaired interval timing, and abnormal symmetry perception. The MEG study on temporal event-structure coding suggests that the superior resolution in the visual domain is probably due to superior access to early perceptual processing in individuals with ASD. Furthermore, those individuals with ASD who show better temporal resolution and superior access to early perceptual processes were characterised by stronger symptom severity in communication and reciprocal interaction. Our findings point towards an abnormal pattern of timing functions in ASD, which is not necessarily in keeping with ideas of a mere impairment of timing perception in ASD as suggested by some previous research studies. In comparison to previous studies we did not only test timing functions in the second range and found impairment in individuals with ASD but we also tested event timing in the millisecond range and found that individuals with ASD were superior in resolving visual information at that range. Hence, we speculate that enhanced perception of timing in the millisecond range together with impairment of timing in the range of seconds could point towards a temporal equivalent of Weak Central Coherence Theory. We suggest that perception in individuals with ASD is characterised by increased parsing of events in time and impaired integration of information over time. In summary, the current research revealed that people with ASD show a very characteristic pattern of timing abnormalities (different from neurotypicals and also from other developmental disorders) with superior processing of information in the range of milliseconds but impairment of perception of durations in longer time ranges. These findings suggest that people with ASD might perceive the timing of events in the world differently from neurotypicals. In particular, non-verbal communication (e.g., turn-taking) has been argued to depent on well-tuned timing functions. We found that those individuals with ASD who showed the most distinct timing patterns had also particular problems with non-verbal communication.
