Transition to synchronization in functional brain networks of children suffering from ADHD.

The synchronization phenomenon is one of the crucial collective behaviors of the brain network, with its abnormal patterns in the brain networks of individuals with mental disorders like attention deficit hyperactivity disorder (ADHD) capturing the interest of researchers. ADHD is a prevalent disorder among children, which is linked to adverse outcomes such as impaired recognition of others' emotional facial expressions, leading to awkward social interactions. Despite numerous studies focusing on the synchronization analysis of brain networks in ADHD children while observing emotional facial expressions, the path to synchronization in these networks has been overlooked. For this reason, this research aims to investigate the differences in the synchronization transition of brain networks between healthy and ADHD children while processing emotional facial expressions based on their electroencephalogram signals. The analysis of synchronization cluster sequences in children's brain networks reveals that the formation and progression of synchronization clusters toward complete synchronization follow a more organized and goal-directed pattern in the healthy group than in the ADHD group. Furthermore, examining synchronization clusters with significant differences in stability (P-values < 0.05) during the clustering sequence between the two groups highlights abnormal synchronization in the frontal brain region during the early stages of neural processing in the ADHD group. This finding may contribute to deficits in attentional control and emotional regulation observed in ADHD children. Moreover, the classification results indicate the high potential of synchronization transition-based features to distinguish between ADHD and healthy children, with maximum accuracy, precision, and sensitivity of 82%, 77%, and 90%, respectively.