Alterations of hubs related to disease progression in patients with temporal lobe epilepsy: a study on topological properties of brain networks / 中华神经科杂志

Objective:To investigate the alterations of brain functional network related to disease progression in patients with temporal lobe epilepsy (TLE) and the potential neural mechanism of executive dysfunction.Methods:Nineteen temporal lobe epilepsy patients with a disease course of less than or equal to 5 years (TLE-SD group) and 24 temporal lobe epilepsy patients with a disease course of more than 5 years (TLE-LD group) were recruited from the Epilepsy Clinic of the First Affiliated Hospital of Guangxi Medical University from December 2019 to December 2021. At the same time, 21 healthy control individuals (healthy control group) were recruited from the society and matched with gender, age, and education level. All subjects were evaluated demographic and clinical data, and performed resting state functional magnetic resonance imaging (rs-fMRI) and attention network test (ANT). The topological properties of functional brain network of 3 groups of subjects were calculated using graph theory, and then the hubs were determined. Then the inter-group comparison of hubs properties was carried out, and the correlation analysis with executive control function was performed.Results:The distribution pattern of hub nodes in TLE-SD patients was changed. Compared with the TLE-LD and healthy control groups, the TLE-SD group significantly increased the nodal degree values in brain regions such as the ventrolateral area of the left middle frontal gyrus, the left anterior central gyrus (upper limb area), the cephalic and caudal areas of the left parietal lobule, as well as the inner parietal lobe area, the caudal side of the right parietal lobule, and the right lateral occipital cortex. The nodal values of the brain areas such as the lateral and parietal inner area, the caudal side of the right upper upper lobule, and the right lateral occipital cortex were significantly increased. TLE-SD patients had a significant increase in the middle of the right upper frontal gyrus and the head of the left upper upper lobule. The node efficiency was significantly lower than that of TLE-LD patients, and the node efficiency in the middle of the right upper frontal gyrus was significantly lower than that of the healthy control group. The node network attributes of the left upper lobe were positively correlated with the execution control efficiency, and negatively correlated with the orientation efficiency. No significant difference was detected between TLE-LD patients and healthy controls.Conclusions:In TLE patients, the hubs in the middle of the right superior frontal gyrus were first damaged, and new hubs appeared in the dorsal attention network, the left anterior central gyrus and the right occipital lobe and were overloaded. With the progression of the disease, hubs tended to be redistributed to normality. The left superior parietal lobule may play an important role in the impairment of executive control function in TLE patients.

Frequency-Resolved Connectome Hubs and Their Test-Retest Reliability in the Resting Human Brain / 神经科学通报·英文版

Functional hubs with disproportionately extensive connectivities play a crucial role in global information integration in human brain networks. However, most resting-state functional magnetic resonance imaging (R-fMRI) studies have identified functional hubs by examining spontaneous fluctuations of the blood oxygen level-dependent signal within a typical low-frequency band (e.g., 0.01-0.08 Hz or 0.01-0.1 Hz). Little is known about how the spatial distributions of functional hubs depend on frequency bands of interest. Here, we used repeatedly measured R-fMRI data from 53 healthy young adults and a degree centrality analysis to identify voxelwise frequency-resolved functional hubs and further examined their test-retest reliability across two sessions. We showed that a wide-range frequency band (0.01-0.24 Hz) accessible with a typical sampling rate (fsample = 0.5 Hz) could be classified into three frequency bands with distinct patterns, namely, low-frequency (LF, 0.01-0.06 Hz), middle-frequency (MF, 0.06-0.16 Hz), and high-frequency (HF, 0.16-0.24 Hz) bands. The functional hubs were mainly located in the medial and lateral frontal and parietal cortices in the LF band, and in the medial prefrontal cortex, superior temporal gyrus, parahippocampal gyrus, amygdala, and several cerebellar regions in the MF and HF bands. These hub regions exhibited fair to good test-retest reliability, regardless of the frequency band. The presence of the three frequency bands was well replicated using an independent R-fMRI dataset from 45 healthy young adults. Our findings demonstrate reliable frequency-resolved functional connectivity hubs in three categories, thus providing insights into the frequency-specific connectome organization in healthy and disordered brains.

The degree and distribution of hub regions of the brain structural networks in schizophrenia / 中华行为医学与脑科学杂志

Objective To explore the differences of the degree and distribution of hub regions of the brain structural networks between the schizophrenia and healthy and then analysis the importance of brain regions in the information transmission in across the whole brain.Methods The diffusion tensor imaging data were obtained from 22 schizophrenia patients and 24 healthy controls.The whole cerebral cortex was parcellated into 90 regions by the anatonical label map.Tractography was performed in the whole cerebral cortex of each subject to reconstruct white matter tracts of the brain using the fiber assignment by continuous tracking (FACT) algorithm.And then the brain structural binary networks were constructed using the complex network theory.The average degree of the network and the degree of the nodes in the network between the brain structural networks of both groups were examined by two sample t-tests.Results The average degree of the brain structural network in the patient group (7.82±0.56) decreased significantly when compared with the control group (8.17 ±0.56; P=0.04).The degree of the nodes in the brain structural network of the patient group (the left hippocampus:11.41 ± 1.84; the left parahippocampal gyrus:6.41± 1.33 ; the left calcarine fissure:11.50±2.97 ; the left fusiform gyrus:8.27± 1.83) decreased significantly when compared with the control group (14.43±2.26; 8.54±2.15; 14.79±2.80; 10.25± 1.36; all P＜0.01,survived critical FDR threshold for multiple comparisons).And the distribution of the hub regions in the temporal and occipital lobes of the patient group was difference from that of the control group.Conclusion The importance of the hippocampus and the brain regions in the occipital lobe is decrease for the information transmission across the whole brain.The damage of the topological properties of these brain regions maybe related to the disorder of the transmission and integration of information in the brain of the schizophrenia.