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Research has shown that abnormal brain networks in patients with schizophrenia appear at different frequencies, but the relationship between these different frequencies is unclear. Therefore, it is necessary to use a multilayer network model to evaluate the integration of information from different frequency bands. To explore the mechanism of integration and separation in the multilayer network of schizophrenia, we constructed multilayer frequency brain network models in 50 patients with schizophrenia and 69 healthy subjects, and the entropy of the multiplex degree (EMD) and multilayer clustering coefficient (MCC) were calculated. The results showed that the ability to integrate and separate information in the multilayer network of patients was significantly higher than that of normal people. This difference was mainly reflected in the default mode network, sensorimotor network, subcortical network, and visual network. Among them, the subcortical network was different in both MCC and EMD outcomes. Furthermore, differences were found in the posterior cingulate gyrus, hippocampus, amygdala, putamen, pallidum, and thalamus. The thalamus and posterior cingulate gyrus were associated with the patient's symptom scores. Our results showed that the cross-frequency interaction ability of patients with schizophrenia was significantly enhanced, among which the subcortical network was the most active. This interaction may serve as a compensation mechanism for intralayer dysfunction. [ABSTRACT FROM AUTHOR]

The hippocampus is generally reported as one of the regions most impacted by Alzheimer's disease (AD) and is closely associated with memory function and orientation. Undirected functional connectivity (FC) alterations occur in patients with mild cognitive impairment (MCI) and AD, and these alterations have been the subject of many studies. However, abnormal patterns of directed FC remain poorly understood. In this study, to identify changes in directed FC between the hippocampus and other brain regions, Granger causality analysis (GCA) based on voxels was applied to resting-state functional magnetic resonance imaging (rs-fMRI) data from 29 AD, 65 MCI, and 30 normal control (NC) subjects. The results showed significant differences in the patterns of directed FC among the three groups. There were fewer brain regions showing changes in directed FC with the hippocampus in the MCI group than the NC group, and these regions were mainly located in the temporal lobe, frontal lobe, and cingulate cortex. However, regarding the abnormalities in directed FC in the AD group, the number of affected voxels was greater, the size of the clusters was larger, and the distribution was wider. Most of the abnormal connections were unidirectional and showed hemispheric asymmetry. In addition, we also investigated the correlations between the abnormal directional FCs and cognitive and clinical measurement scores in the three groups and found that some of them were significantly correlated. This study revealed abnormalities in the transmission and reception of information in the hippocampus of MCI and AD patients and offer insight into the neurophysiological mechanisms underlying MCI and AD. [ABSTRACT FROM AUTHOR]

• Brain network is controllable but is not easily controllable. • The network synchronization was significantly higher in schizophrenia. • Brain network topology differences dictate distinct in controlling the trajectories. Cognitive dysfunction may be central to neurocognitive deficits in schizophrenia. To further explore brain network dynamics and synchronization in first-episode schizophrenia, we exploited pinning control theory to adjust and control the brain regions interacting with each other in schizophrenia to make their network synchronization stability consistent with that of healthy individuals. Our results revealed that in a short-term memory task, the right frontal lobe was abnormal in schizophrenia, resulting in higher synchronous oscillation behavior of the entire brain networks compared with the healthy participants. And the synchronization was positively correlated with each participant's response time (RT) and negatively correlated with their response accuracy (ACC). In the healthy participants, the frontal lobe facilitated a higher brain synchronization state, whereas in the schizophrenia patients, the parietal-occipital lobe facilitated a higher brain synchronization state. These data provide new evidence for task-relevant dynamic interactions between brain regions in schizophrenia and provide theoretical methods for the adjustment and control of brain networks. [ABSTRACT FROM AUTHOR]