Anticipating, complete and lag synchronizations in RC phase-shift network based coupled Chua's circuits without delay

Boosting of stable synchronization in coupled non-identical counter-rotating chaotic systems

Achieving synchronization in coupled non-identical chaotic systems has been a difficult endeavor, and improving the stability of synchronization in such systems poses additional challenges. This research work addresses these challenges by identifying stable synchronization in coupled non-identical chaotic systems and enhancing its stability. The study explores chaotic attractors that arise from various system parameters to provide generalized results. Furthermore, the impact of the transient uncoupling factor on improving synchronization stability in coupled non-identical counter-rotating chaotic oscillators is discussed. By investigating these aspects, the research aims to contribute to the understanding and advancement of synchronization in coupled non-identical chaotic systems.

Anticipated synchronization in human EEG data: Unidirectional causality with negative phase lag

Understanding the functional connectivity of the brain has become a major goal of neuroscience. In many situations the relative phase difference, together with coherence patterns, has been employed to infer the direction of the information flow. However, it has been recently shown in local field potential data from monkeys the existence of a synchronized regime in which unidirectionally coupled areas can present both positive and negative phase differences. During the counterintuitive regime, called anticipated synchronization (AS), the phase difference does not reflect the causality. Here we investigate coherence and causality at the alpha frequency band (f∼10 Hz) between pairs of electroencephalogram (EEG) electrodes in humans during a GO/NO-GO task. We show that human EEG signals can exhibit anticipated synchronization, which is characterized by a unidirectional influence from an electrode A to an electrode B, but the electrode B leads the electrode A in time. To the best of our knowledge, this is the first verification of AS in EEG signals and in the human brain. The usual delayed synchronization (DS) regime is also present between many pairs. DS is characterized by a unidirectional influence from an electrode A to an electrode B and a positive phase difference between A and B which indicates that the electrode A leads the electrode B in time. Moreover we show that EEG signals exhibit diversity in the phase relations: the pairs of electrodes can present in-phase, antiphase, or out-of-phase synchronization with a similar distribution of positive and negative phase differences.