by Kanika Bansal (CCDC US Army Research Laboratory & Columbia University, New York, NY, USA).
Analyses of neural avalanches, in combination with other methods rooted in complex systems theory, provide support for the brain criticality hypothesis, however, it is still unclear how the criticality framework would account for the omnipresent cognitive variability, across individuals and tasks. In order to explore how changing cognitive demands impact the spatiotemporal distributions of macroscopic neural avalanches, we analyzed electroencephalography (EEG) activity of healthy humans during different task conditions including a resting state. Our first set of results indicated that the features describing the dynamics of avalanches varied between individuals and tasks such that, the global (whole-brain-level) distributions remain scale-invariant, while regional probabilities change in a scale-specific manner [Bansal et al. (2020), arXiv:2003.06463]. We defined a region-specific metric, ‘normalized engagement’, that captures the relative probability of a brain region to engage in observed avalanches. During varying cognitive task demands, we found that the normalized engagement of different brain regions also changed systematically and even correlated with task performance. Contrary to a popular theoretical perspective which suggests that the features describing the dynamics of avalanches are universal, we found both the global and regional avalanche features to vary between individuals and tasks. Moreover, in ongoing work extending this research to the clinical domain, our results suggest a hemispheric asymmetry in normalized engagement in patients suffering from the major depression disorder. Our results suggest that the study of avalanches in human brain activity not only provides a tool to understand the cognitive variability but may also in the future assist in clinical diagnosis.
Spotlight talk presented on October 6th 2020, at the Brain Criticality Virtual Conference 2020 (Plenz D., Chialvo D., de Arcangelis L. & Battaglia D. organizers)