Análise da conectividade em dados de eletroencefalograma de pessoas com transtorno do déficit de atenção e hiperatividade

Abstract

The understanding of the functional connectivity of the brain has become a major goal of neuroscience. In many situations, the relative phase difference and the coherence patterns have been employed to infer the direction of the information flow. However, it has been recently shown that for local field potential data from monkeys the existence of a synchronized regime in which unidirectionally coupled areas can present negative phase difference, phenomena called anticipated synchronization. During this counterintuitive regime, the phase difference does not reflect the causality. Here we show that EEG signals from humans with Attention Deficit Hyperactivity Disorder (ADHD) can exhibit anticipated synchronization, which is characterized by a unidirectional flow of information from an electrode A to an electrode B, but electrode A lags behind B in time. Moreover, the signals exhibit diversity in the phase relations. The pairs of electrodes can synchronize in-phase, anti-phase, and out-of-phase with positive or negative phase differences. We also show that considering all the subjects the unidirectional flow in the functional connectivity is very common during the waiting time before the beginning of the task. We compared the data from these patients with the data from a group of volunteers and observed some differences in the number and type of synchronization.