The hierarchy system of functional human brain revealed by intracranial electroencephalography.  Dongju Yang , Aihua Liu, Tao Yu, Yuping Wang (this work has not been published yet, Beijing, China)   C4

Object: The human brain is a complex network system. There is specific hierarchy in the cognitive processing of the brain. Revealing the functional hierarchy of the brain aid in understanding cognition and modulating brain disorders. The aim of this study is to explore the hierarchical system of functional brain operating cognitive processes and reveal the key regions in cognition, with intracranial intracranial electroencephalography. Method: Epilepsy patients with intracranial electrodes implanted were enrolled and performed three S1-S2 delay matching tasks. Patients were asked to decide whether there is shape difference, border line difference or dual feature difference. Averaging and statistical analyzing intracranial electroencephalography, the electrodes were labeled as one of the four function:"shape distinguishing", "border line distinguishing", "shape and border line distinguishing" and "no feature distinguishing". Through brain image registration and spatial standardization, electrodes with different function were depicted on a brain surface. To explore neural reorganization in different tasks, the spatial distribution patterns of different function were analysed. One-way analysis of variance and chi-square test was used for statistical analysis, and p less than 0.05 was considered as significant difference. Result: Twenty patients with intracranial electrodes implanted were enrolled. It was found that, there was "automatic" and "active" system inside the brain operating single feature distinguishment. There were electrodes distinguishing shape or border line, regardless of the patient's task goal. The distribution of electrodes with "shape distinguishing" and "border line distinguishing" was different. Electrodes' function changed as the brain operating two feature distinguishment simultaneously. The functional brain network is divided into two layers and four categories, according to neural reorganization pattern revealed in the brain manipulating single feature only and manipulating two features simultaneously. The first category-first layer (IA) of functional brain is composed of the right occipital- posterior and lateral temporal lobe, right base of temporal lobe, and right posterior frontal lobe. There areas are automatically involved and feature non-specific. The second category -first layer functional brain (IB) is composed of right inferior parietal lobe, right posterior insular, left occipital - posterior temporal lobe, left intraparietal sulcus, left anterior insular, left posterior and middle part of frontal lobe and left anterior cingulate gyrus. They are involved automatically and feature specific. The first category - second layer functional brain (IIA) is composed of left lateral and base of temporal lobe, and left posterior insular, which are involved actively and feature non-specific. The second category -second layer functional brain (IIB) locates in right anterior insular and right middle part of frontal lobe, which are involved actively and feature specific. Conclusion: The brain showed neural reorganization in indifferent cognitive tasks, which suggested the existence of hierarchy system in the functional brain.