Autism spectrum disorder is increasingly understood to be based on atypical signal transfer among multiple interconnected networks in the brain. Relative temporal patterns of neural activity have been shown to underlie both the altered neurophysiology and the altered behaviors in a variety of neurogenic disorders. We assessed brain network dynamics variability in Autism Spectrum Disorders (ASD) using measures of synchronization (phase-locking) strength, and timing of synchronization and desynchronization of neural activity (desynchronization ratio) across frequency bands of resting state EEG. Our analysis indicated that fronto-parietal synchronization is higher in ASD, but with more short periods of desynchronization. It also indicates that the relationship between the properties of neural synchronization and behavior is different in ASD and typically developing populations. Recent theoretical studies suggest that neural networks with high desynchronization ratio have increased sensitivity to inputs. Our results point to the potential significance of this phenomenon to autistic brain. This sensitivity may disrupt production of an appropriate neural and behavioral responses to external stimuli. Cognitive processes dependent on integration of activity from multiple networks may be, as a result, particularly vulnerable to disruption.
Lay SummaryParts of the brain can work together by synchronizing activity of the neurons. We recorded electrical activity of the brain in adolescents with autism spectrum disorder, and then compared the recording to that of their peers without the diagnosis. We found that in participants with autism, there were a lot of very short time periods of non-synchronized activity between frontal and parietal parts of the brain. Mathematical models show that the brain system with this kind of activity is very sensitive to external events.
IntroductionHuman behavior in health and disease is undergirded by temporal synchronization of distributed networks, which allows for information processing (e.g., Buzsaki, 2006;Harris & Gordon, 2015). The difficulty in understanding of the temporal regulation of brain networks is partially due to the disparity of temporal scales for different types of neural data (e.g. between millisecond scale of brain-activity-driven EEG and second-to-minute scale of blood-flow-based fMRI).Experimental data from different modalities, such as EEG, MEG, and fMRI, indicate that better understanding of temporal dynamics of brain activity may help elucidate mechanisms of brain network organization in ASD population. During rest, ASD participants show increased coherence (or, static overconnectivity) in long-range brain networks (Buckley et al., 2015). However, the increase in coherence coincides with longer dwell times in a globally-disconnected state (Rashid et al., 2018), and increased variability in connectivity over time (Mash et al., 2019). Analyses of EEG and MEG recordings, which provide higher temporal resolution, indicate longrange functional underconnectivity (O'Reilly ...