Clinical grading diagnosis of disorder of consciousness (DOC) patients relies on behavioral assessment, which has certain limitations. Combining multi-modal technologies and brain-computer interface (BCI) paradigms can assist in identifying patients with minimally conscious state (MCS) and vegetative state (VS). This study collected electroencephalogram (EEG) and functional near-infrared spectroscopy (fNIRS) signals under motor BCI paradigms from 14 DOC patients, who were divided into two groups based on clinical scores: 7 in the MCS group and 7 in the VS group. We calculated event-related desynchronization (ERD) and motor decoding accuracy to analyze the effectiveness of motor BCI paradigms in detecting consciousness states. The results showed that the classification accuracies for left-hand and right-hand movement tasks using EEG were 93.28% and 76.19% for the MCS and VS groups, respectively; the classification precisions using fNIRS were 53.72% and 49.11% for these groups. When combining EEG and fNIRS features, the classification accuracies for left-hand and right-hand movement tasks in the MCS and VS groups were 95.56% and 87.38%, respectively. Although there was no statistically significant difference in motor decoding accuracy between the two groups, significant differences in ERD were observed between different consciousness states during left-hand movement tasks (P < 0.001). This study demonstrates that motor BCI paradigms can assist in assessing the level of consciousness, with EEG being more sensitive for evaluating residual motor intention intensity. Moreover, the ERD feature of motor intention intensity is more sensitive than BCI classification accuracy.
Objective To investigate the expression pattern of hypoxia-inducible factor 1α (HIF-1α) in experimental secondary spinal cord injury (SSCI) in rats and its potential effects on SSCI. Methods A total of 66 SD rats (female or male) with weight (250 ± 20) g were randomly divided into 3 groups: normal control group (group A, n=6), pseudo injury group (group B, n=6), and spinal cord injury (SCI) group (group C, n=54). In group A, no treatment was given as normal control. In groupB, only laminectomy was appl ied. In group C, laminectomy was appl ied and static compression model of SCI was built at T10 level. The expression of HIF-1α was measured with HE and immunohistochemical staining in groups A, B (1 hour after pseudo injury), and C (1, 3, 6, 12 hours and 1, 2, 3, 7, 14 days after SCI). Results All rats survived to the end of the experiment. HE staining showed that the spinal tissue of groups A and B were dense and the nucleus were round and big with l ight staining and clear nucleolus. The injured neuron at 1-12 hours after SCI of group C presented pyknosis and deep eosin staining. The swelling axon with bubbles and the disintegrated and disorganized medullary sheath in white matter appeared at 1-3 days after SCI. The hyperplasia of gl ial cells were obvious and gray matter cells were broken and apoptosis with cavities in injured spinal segment was observed at 7 and 14 days after SCI. Immunohistochemical staining showed that HIF-1α was poorly expressed in group A and increased a l ittle in group B. The positive expression in group C increased at 3 hours after SCI, which was found in spinal cord anterior horn neurons and a small amount of gangl ion cells. It reached peak at 1 day, maintained at a high level during 1-3 days and then decl ined. At 14 days, it appeared only in a small amount of gangl ion cells of white matter. There was no significant difference in the number of HIF-1α positive cells between groups A and B (t=1.325, P=0.137). The number of HIF-1α positive cells at each time point in group C was more than those in groups A and B (P lt; 0.05), and there were significant differences between all time points in group C (P lt; 0.05). Conclusion The expression of HIF-1α increases after SCI, it is related to the ischemia hypoxia after SSCI, and the expression pattern was correlated with the injury time.
