Dynamic analysis of epileptic causal brain networks based on directional transfer function / 生物医学工程学杂志

Epilepsy is a neurological disease with disordered brain network connectivity. It is important to analyze the brain network mechanism of epileptic seizure from the perspective of directed functional connectivity. In this paper, causal brain networks were constructed for different sub-bands of epileptic electroencephalogram (EEG) signals in interictal, preictal and ictal phases by directional transfer function method, and the information transmission pathway and dynamic change process of brain network under different conditions were analyzed. Finally, the dynamic changes of characteristic attributes of brain networks with different rhythms were analyzed. The results show that the topology of brain network changes from stochastic network to rule network during the three stage and the node connections of the whole brain network show a trend of gradual decline. The number of pathway connections between internal nodes of frontal, temporal and occipital regions increase. There are a lot of hub nodes with information outflow in the lesion region. The global efficiency in ictal stage of α, β and γ waves are significantly higher than in the interictal and the preictal stage. The clustering coefficients in preictal stage are higher than in the ictal stage and the clustering coefficients in ictal stage are higher than in the interictal stage. The clustering coefficients of frontal, temporal and parietal lobes are significantly increased. The results of this study indicate that the topological structure and characteristic properties of epileptic causal brain network can reflect the dynamic process of epileptic seizures. In the future, this study has important research value in the localization of epileptic focus and prediction of epileptic seizure.

Connectivity pattern of action potentials causal network in prefrontal cortex during anxiety / 生物医学工程学杂志

Anxiety disorder is a common emotional handicap, which seriously affects the normal life of patients and endangers their physical and mental health. The prefrontal cortex is a key brain region which is responsible for anxiety. Action potential and behavioral data of rats in the elevated plus maze (EPM) during anxiety (an innate anxiety paradigm) can be obtained simultaneously by using the and in conscious animal multi-channel microelectrode array recording technique. Based on maximum likelihood estimation (MLE), the action potential causal network was established, network connectivity strength and global efficiency were calculated, and action potential causal network connectivity pattern of the medial prefrontal cortex was quantitatively characterized. We found that the entries (44.13±6.99) and residence period (439.76±50.43) s of rats in the closed arm of the elevated plus maze were obviously higher than those in the open arm [16.50±3.25, <0.001; (160.23±48.22) s, <0.001], respectively. The action potential causal network connectivity strength (0.017 3±0.003 6) and the global efficiency (0.044 2±0.012 8) in the closed arm were both higher than those in the open arm (0.010 4±0.003 2, <0.01; 0.034 8±0.011 4, <0.001), respectively. The results suggest that the changes of action potential causal network in the medial prefrontal cortex are related to anxiety state. These data could provide support for the study of the brain network mechanism in prefrontal cortex during anxiety.

The global efficiency of the brain structural networks and its relationship with the psychotic symptoms in male paranoid schizophrenia / 中华行为医学与脑科学杂志

Objective To explore the differences of the global efficiency of the brain structural networks between the male paranoid schizophrenia and male healthy and its relationship with the psychotic symptoms of the schizophrenia.Methods The diffusion tensor imaging data were obtained from 27 male paranoid schizophrenia patients and 28 male healthy controls.The whole cerebral cortex was parcellated into 90 regions by the anatomical label map.Tractography was performed in the whole cerebral cortex of each subject to reconstruct white matter tracts of the brain using fiber assignment by continuous tracking(FACT) algorithm.And then the brain structural binary networks were constructed using the complex network theory.The average global efficiency of the brain network and the global efficiency of the nodes of both groups were examined by two sample t-test and its relationship with the psychotic symptoms in the male paranoid schizophrenia was explored by the correlation analysis.Results Compared with control group,the average global efficiency of the brain network of the patients decreased significantly (7.87±0.56,8.17±0.56,P=0.005),and the global efficiency of the nodes in the brain network of the patient decreased significantly in the left superior frontal gyrus (orbital part) (P=0.00025),the left superior parietal gyrus (P=0.00011),the left cuneus (P=0.00012) and the left putamen (P=0.00032),all survived FDR correction.Significant negative correlation was found between the global efficiency of the left putamen and the total scores (r=-0.43,P=0.03),the positive scores (r=-0.41,P=0.03) and the cognitive scores (r=-0.40,P=0.04) of PANSS.Conclusion The decreased global efficiency of the left frontal,parietal and occipital lobes and the subcortical structures lead to the occurrence of schizophrenia.And the reduced efficiency of the subcortical structures is associated with the positive symptoms and the abnormal cognitive function of the patients.