Random matrix theory for analysing the brain functional network in lower limb motor imagery.

We use random matrix theory (RMT) to investigate the statistical properties of brain functional networks in lower limb motor imagery. Functional connectivity was calculated by Pearson correlation coefficient (PCC), mutual information (MTI) and phase locking value (PLV) extracted from EEG signals. We found that when the measured subjects imagined the movements of their lower limbs the spectral density as well as the level spacings displayed deviations from the random matrix prediction. In particular, a significant difference between the left and right foot imaginary movements was observed in the maximum eigenvalue from the PCC, which can provide a theoretical basis for further study on the classification of unilateral movement of lower limbs.

EEG-based Classification of Lower Limb Motor Imagery with Brain Network Analysis.

This study aims to investigate the difference in cortical signal characteristics between the left and right foot imaginary movements and to improve the classification accuracy of the experimental tasks. Raw signals were gathered from 64-channel scalp electroencephalograms of 11 healthy participants. Firstly, the cortical source model was defined with 62 regions of interest over the sensorimotor cortex (nine Brodmann areas). Secondly, functional connectivity was calculated by phase lock value for α and ß rhythm networks. Thirdly, network-based statistics were applied to identify whether there existed stable and significant subnetworks that formed between the two types of motor imagery tasks. Meanwhile, ten graph theory indices were investigated for each network by t-test to determine statistical significance between tasks. Finally, sparse multinomial logistic regression (SMLR)-support vector machine (SVM), as a feature selection and classification model, was used to analyze the graph theory features. The specific time-frequency (α event-related desynchronization and ß event-related synchronization) difference network between the two tasks was congregated at the midline and demonstrated significant connections in the premotor areas and primary somatosensory cortex. A few of statistically significant differences in the network properties were observed between tasks in the α and ß rhythm. The SMLR-SVM classification model achieved fair discrimination accuracy between imaginary movements of the two feet (maximum 75% accuracy rate in single-trial analyses). This study reveals the network mechanism of the discrimination of the left and right foot motor imagery, which can provide a novel avenue for the BCI system by unilateral lower limb motor imagery.

Antioxidant, anticancer and apoptotic effects of the Bupleurum chinense root extract in HO-8910 ovarian cancer cells.

PURPOSE: The purpose of this study was to evaluate the anticancer, apoptotic and antioxidant properties of Bupleurum chinense (B.C) root extract against human epithelial ovarian cancer cells (HO-8910) in vitro. METHODS: MTT assay was used to evaluate the cell viability of HO-8910 cells after treatment with different B.C extract doses. Apoptotic and morphological effects induced by the extract were demonstrated by inverted phase contrast microscopy and fluorescence microscopy. The percentage of apoptotic cells was quantified by Annexin V/PI double staining assay. Flow cytometry using rhodamine-123 dye was used to measure disruption of mitochondrial membrane potential (Δψm). Gel electrophoresis was used to study the effects of the extract on DNA fragmentation. The antioxidant activity of the extract using 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazolin-6-sulphonic acid) (ABTS) radical scavenging assays was also evaluated. RESULTS: The results showed that B.C extract could induce potent and dose-dependent cytotoxic effects on the HO-8910 cells as demonstrated by MTT assay. The extract also induced cell shrinkage, chromatin condensation and membrane blebbing which are the hallmark of apoptosis. The average proportion of Annexin V-staining positive cells (total apoptotic cells) significantly increased from 9.4% in control cells to 18.5, 28.2 and 50.5% in 20, 80 and 120 µg/ml B.C extract-treated cells respectively. Different doses of the extract (20, 80 and 120 µg/ml) after 48 hrs exposure led to a substantial increase in DNA fragmentation.The number of cells with disrupted Δψm increased from 6.6% in untreated (control cells) to 14.2, 42.1 and 73.4% in 20, 80 and 120 µg/ml in extract-treated cells, respectively CONCLUSION: The anticancer effects of Bupleurum chinense extract were mediated through the induction of apoptosis, DNA fragmentation and disruption of mitochondrial membrane potential.

Effects of Zuogui Pill () and Yougui Pill () on the expression of brain-derived neurotrophic factor and cyclic adenosine monophosphate/protein kinase A signaling transduction pathways of axonal regeneration in model rats with experimental autoimmune encephalomyelitis.

OBJECTIVE: To study the effects of Zuogui Pill (, ZGP) and Yougui Pill (, YGP) on the expressions of brain-derived neurotrophic factor (BDNF) and cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling of axonal regeneration in the Lewis rats with experimental autoimmune encephalomyelitis (EAE), in order to explore the possible mechanism of ZGP and YGP on promoting axonal regeneration. METHODS: The rats were randomly divided into normal control (NC), model (MO), prednisone acetate (PA), ZGP and YGP groups. The EAE model of rat was established by injecting antigen containing myelin basic protein (MBP)68-86. The brain and spinal cord were harvested on the 14th and 28th day post-immunization (PI), the protein and mRNA expression of BDNF and PKA in the brain and spinal cord of rats were detected by Western blot analysis and real-time quantitative polymerase chain reaction (PCR), and the cAMP levels were detected by using enzyme-immunoassay method. RESULTS: (1) On the 28th day PI, the mRNA expression of BDNF in brain white matter and spinal cord of rats in ZGP and YGP groups were up-regulated, especially in YGP group (P<0.05 or P<0.01). (2) On the 14th day PI, the cAMP levels in brain white matters significantly increased in PA and YGP groups compared with MO group (P<0.05 or P<0.01), and the cAMP level in YGP group was higher than that in ZGP group (P<0.05). The cAMP level in spinal cord also significantly increased in YGP group compared with MO, PA and ZGP groups, respectively (P<0.01). (3) On the 14th day PI, the PKA expression in spinal cord of rats in ZGP group was significantly decreased compared with MO and YGP groups, respectively (P<0.05). (4) On the 28th day PI, there was a positive correlation between cAMP and PKA expression in the brain white matter of YGP rats. CONCLUSIONS: The results suggest that ZGP and YGP may promote axonal regeneration by modulating cAMP/PKA signal transduction pathway, but the targets of molecular mechanism of ZGP may be different from those of YGP.