For this purpose, we derived two different synchronization measures - Phase Locking Index (PLI) and Phase Coherence (PC) - to assess EEG phase synchronization across trials under single electrodes and between different electrode locations, respectively. These measures are indicators of phase stability or constancy of instantaneous phase changes across trials and can be termed as “true” synchronization measures. Based on findings in the literature that are related to conflict monitoring and response inhibition, we decided to restrict our analyses to frequency bands below 20 Hz. As mentioned above, changes in the N2 and P3 ERP components, which probably reflect low-frequency oscillations (e.g., in the delta-alpha range), have been observed in the context of Go/NoGo task representations. In addition, low-frequency oscillations are involved in different cognitive functions and task performance. Theta oscillations are particularly prominent, with possible functional roles covering a wide range of behavior from arousal, attention and memory to orienting reflex, conditioning and learning, including different binding and information processing mechanisms [31]. Similar, enhanced oscillatory activity at the delta frequency during cognitive tasks may be an indicator of attention
