The Relationship Between The Phase Synchronization Of Low Frequency Brain Signal And Cognitive Activity

Cognitive activity relies on functionally organized involving information communication between multiple regions of the brain.Phase synchronization serves as an important mechanism for information exchange between brain regions,and bridges the collaborative communication between various regions of the brain.In the low frequency range,phase synchronization between regions is extremely important for brain function.In recent years,phase synchronization has become an important tool in revealing the synchrony and interactions of regions distributed throughout the brain.However,the specific role of phase synchronization in cognitive processing is still unclear.Recent advance in brain functional magnetic resonance imaging(fMRI)techniques and frequency tagging experimental paradigms allows for studying the relationship between low frequency phase synchronization and brain cognition activity.The work of this dissertation mainly includes the following two parts:In the first part,we compared the phase delay and phase coherence of the task state and resting state,and found that there were two separate systems in the face recognition,the face processing system and the links between face processing system and fronto-parietal network.Compared with the phase delay of resting state,the phase delays of task within the core processing system and between the core processing system and the extended system were significantly decreased,while the phase delay between the face processing system and the fronto-parietal network was increased.These findings indicate the reorganization of inter-regional relations in the two systems during face recognition.The phase delay between regions is modulated by the ascending and descending phases of the blood oxygenation level dependent(BOLD)signal,indicating the phase-dependent relationship of phase delay between regions.During the task,the phase coherence within the face processing system increased significantly,emphasizing the important role of specific phase relationships between regions for face recognition.In addition,the phase delays between the visual cortex and the amygdala,and between the visual cortex and the motor cortex were positively correlated with the reaction time,indicating that better behavioral performance was related to rapid emotional detection and visual motion pathways.In the second part,we further investigated the relationship between phase synchronization of brain signal and cognitive activities in different cognitive tasks.We analyzed the phase delay and phase coherence of different task contrasts in attention task,including alerting-orienting,alerting-executive control,orienting-executive control,alerting-baseline,orienting-baseline,and executive control-baseline.We found significant difference in phase delay and phase coherence between orienting-alerting and between orienting-baseline.Compared with alerting-baseline,the phase delay of the orienting network significantly decreased and the phase coherence was increased.There was no significant difference between other tasks.This shows that the phase delay modulates the three networks included in attention function to different degrees.Through the point-by-point comparison,we found that the phase delay is modulated by the ascending phase and is also consistent with our previous results.In summary,through comparing the task with the resting state during the face recognition processing,and different cognitive tasks during the attention task,we shows that the phase synchronization between functional regions in low frequency is of great significance for effective information communication and better cognitive performance.