With the continuous advancement of neuroimaging technologies, clinical research has discovered the phenomenon of cognitive-motor dissociation in patients with disorders of consciousness (DoC). This groundbreaking finding has provided new impetus for the development and application of brain-computer interface (BCI) in clinic. Currently, BCI has been widely applied in DoC patients as an important tool for assessing and assisting behaviorally unresponsive individuals. This paper reviews the current applications of BCI in DoC patients, focusing four main aspects including consciousness detection, auxiliary diagnosis, prognosis assessment, and rehabilitation treatment. It also provides an in-depth analysis of representative key techniques and experimental outcomes in each aspect, which include BCI paradigm designs, brain signal decoding method, and feedback mechanisms. Furthermore, the paper offers recommendations for BCI design tailored to DoC patients and discusses future directions for research and clinical practice in this field.
Humans ; Brain-Computer Interfaces ; Consciousness Disorders/physiopathology* ; Electroencephalography ; Brain/physiopathology* ; Consciousness

Brain ; drug effects ; physiopathology ; Consciousness ; drug effects ; physiology ; Consciousness Disorders ; diagnosis ; drug therapy ; Humans ; Research

In recent decades, event-related potentials have been used for the clinical electrophysiological assessment of patients with disorders of consciousness (DOCs). In this paper, an oddball paradigm with two types of frequency-deviant stimulus (standard stimuli were pure tones of 1000 Hz; small deviant stimuli were pure tones of 1050 Hz; large deviant stimuli were pure tones of 1200 Hz) was applied to elicit mismatch negativity (MMN) in 30 patients with DOCs diagnosed using the JFK Coma Recovery Scale-Revised (CRS-R). The results showed that the peak amplitudes of MMN elicited by both large and small deviant stimuli were significantly different from baseline. In terms of the spatial properties of MMN, a significant interaction effect between conditions (small and large deviant stimuli) and electrode nodes was centered at the frontocentral area. Furthermore, correlation coefficients were calculated between MMN amplitudes and CRS-R scores for each electrode among all participants to generate topographic maps. Meanwhile, a significant negative correlation between the MMN amplitudes elicited by large deviant stimuli and the CRS-R scores was also found at the frontocentral area. In consequence, our results combine the above spatial properties of MMN in patients with DOCs, and provide a more precise location (frontocentral area) at which to evaluate the correlation between clinical electrophysiological assessment and the level of consciousness.
Acoustic Stimulation ; Adolescent ; Adult ; Aged ; Auditory Perception ; physiology ; Brain Injuries ; complications ; physiopathology ; Consciousness Disorders ; etiology ; physiopathology ; Electroencephalography ; Evoked Potentials ; Female ; Humans ; Male ; Middle Aged ; Neuropsychological Tests ; Severity of Illness Index ; Wavelet Analysis

Adult ; Aged ; Coma ; physiopathology ; Consciousness ; physiology ; Consciousness Disorders ; physiopathology ; therapy ; Female ; Humans ; Male ; Middle Aged ; Persistent Vegetative State ; physiopathology ; Photic Stimulation ; methods ; Recovery of Function ; physiology ; Treatment Outcome

Whether habit stimulation is effective in DOC patient arousal has not been reported. In this paper, we analyzed the responses of DOC patients to habit stimulation. Nineteen DOC patients with alcohol consumption or smoking habits were recruited and 64-channel EEG signals were acquired both at the resting state and at three stimulation states. Wavelet transformation and nonlinear dynamics were used to extract the features of EEG signals and four brain lobes were selected to investigate the degree of EEG response to habit stimulation. Results showed that the highest degree of EEG response was from the call-name stimulation, followed by habit and music stimulations. Significant differences in EEG wavelet energy and response coefficient were found both between habit and music stimulation, and between habit and call-name stimulation. These findings prove that habit stimulation induces relatively more intense EEG responses in DOC patients than music stimulation, suggesting that it may be a relevant additional method for eliciting patient arousal.
Adult ; Alcohol Drinking ; physiopathology ; Brain ; physiopathology ; Consciousness Disorders ; physiopathology ; therapy ; Electroencephalography ; Female ; Habits ; Humans ; Male ; Middle Aged ; Music ; Names ; Nonlinear Dynamics ; Physical Stimulation ; Rest ; Smoking ; physiopathology ; Speech ; Treatment Outcome ; Wavelet Analysis

Visual fixation is an item in the visual function subscale of the Coma Recovery Scale-Revised (CRS-R). Sometimes clinicians using the behavioral scales find it difficult to detect because of the motor impairment in patients with disorders of consciousness (DOCs). Brain-computer interface (BCI) can be used to improve clinical assessment because it directly detects the brain response to an external stimulus in the absence of behavioral expression. In this study, we designed a BCI system to assist the visual fixation assessment of DOC patients. The results from 15 patients indicated that three showed visual fixation in both CRS-R and BCI assessments and one did not show such behavior in the CRS-R assessment but achieved significant online accuracy in the BCI assessment. The results revealed that electroencephalography-based BCI can detect the brain response for visual fixation. Therefore, the proposed BCI may provide a promising method for assisting behavioral assessment using the CRS-R.
Adolescent ; Adult ; Aged ; Brain ; physiopathology ; Brain-Computer Interfaces ; Consciousness Disorders ; diagnosis ; physiopathology ; Diagnosis, Computer-Assisted ; methods ; Electroencephalography ; methods ; Evoked Potentials ; Female ; Fixation, Ocular ; physiology ; Humans ; Male ; Middle Aged ; Neurologic Examination ; Pilot Projects ; Severity of Illness Index ; User-Computer Interface

Spinal cord stimulation (SCS) is a promising technique for treating disorders of consciousness (DOCs). However, differences in the spatio-temporal responsiveness of the brain under varied SCS parameters remain unclear. In this pilot study, functional near-infrared spectroscopy was used to measure the hemodynamic responses of 10 DOC patients to different SCS frequencies (5 Hz, 10 Hz, 50 Hz, 70 Hz, and 100 Hz). In the prefrontal cortex, a key area in consciousness circuits, we found significantly increased hemodynamic responses at 70 Hz and 100 Hz, and significantly different hemodynamic responses between 50 Hz and 70 Hz/100 Hz. In addition, the functional connectivity between prefrontal and occipital areas was significantly improved with SCS at 70 Hz. These results demonstrated that SCS modulates the hemodynamic responses and long-range connectivity in a frequency-specific manner (with 70 Hz apparently better), perhaps by improving the cerebral blood volume and information transmission through the reticular formation-thalamus-cortex pathway.
Adolescent ; Adult ; Brain ; physiopathology ; Consciousness ; physiology ; Consciousness Disorders ; physiopathology ; therapy ; Female ; Hemodynamics ; physiology ; Humans ; Male ; Middle Aged ; Pilot Projects ; Spinal Cord ; physiopathology ; surgery ; Spinal Cord Stimulation ; methods ; Young Adult

In this study, we aimed to (1) identify white matter (WM) deficits underlying the consciousness level in patients with disorders of consciousness (DOCs) using diffusion tensor imaging (DTI), and (2) evaluate the relationship between DTI metrics and clinical measures of the consciousness level in DOC patients. With a cohort of 8 comatose, 8 unresponsive wakefulness syndrome/vegetative state, and 14 minimally conscious state patients and 25 patient controls, we performed group comparisons of the DTI metrics in 48 core WM regions of interest (ROIs), and examined the clinical relevance using correlation analysis. We identified multiple abnormal WM ROIs in DOC patients compared with normal controls, and the DTI metrics in these ROIs were significantly correlated with clinical measures of the consciousness level. Therefore, our findings suggested that multiple WM tracts are involved in the impaired consciousness levels in DOC patients and demonstrated the clinical relevance of DTI for DOC patients.
Adult ; Brain Stem ; diagnostic imaging ; Consciousness ; physiology ; Consciousness Disorders ; diagnostic imaging ; pathology ; Diffusion Tensor Imaging ; methods ; Female ; Humans ; Image Processing, Computer-Assisted ; methods ; Male ; Middle Aged ; White Matter ; pathology ; physiopathology

A number of studies have indicated that disorders of consciousness result from multifocal injuries as well as from the impaired functional and anatomical connectivity between various anterior forebrain regions. However, the specific causal mechanism linking these regions remains unclear. In this study, we used spectral dynamic causal modeling to assess how the effective connections (ECs) between various regions differ between individuals. Next, we used connectome-based predictive modeling to evaluate the performance of the ECs in predicting the clinical scores of DOC patients. We found increased ECs from the striatum to the globus pallidus as well as from the globus pallidus to the posterior cingulate cortex, and decreased ECs from the globus pallidus to the thalamus and from the medial prefrontal cortex to the striatum in DOC patients as compared to healthy controls. Prediction of the patients' outcome was effective using the negative ECs as features. In summary, the present study highlights a key role of the thalamo-basal ganglia-cortical loop in DOCs and supports the anterior forebrain mesocircuit hypothesis. Furthermore, EC could be potentially used to assess the consciousness level.
Adult ; Bayes Theorem ; Connectome ; Consciousness Disorders ; diagnostic imaging ; physiopathology ; Female ; Humans ; Machine Learning ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Neural Pathways ; diagnostic imaging ; physiopathology ; Prognosis ; Prosencephalon ; diagnostic imaging ; physiopathology ; Young Adult

Neuroimaging has opened new opportunities to study the neural correlates of consciousness, and provided additional information concerning diagnosis, prognosis, and therapeutic interventions in patients with disorders of consciousness. Here, we aim to review neuroimaging studies in chronic disorders of consciousness from the viewpoint of the brain network, focusing on positron emission tomography, functional MRI, functional near-infrared spectroscopy, electrophysiology, and diffusion MRI. To accelerate basic research on disorders of consciousness and provide a panoramic view of unconsciousness, we propose that it is urgent to integrate different techniques at various spatiotemporal scales, and to merge fragmented findings into a uniform "Brainnetome" (Brain-net-ome) research framework.
Animals ; Brain ; physiology ; Chronic Disease ; Consciousness ; physiology ; Consciousness Disorders ; physiopathology ; Humans ; Neuroimaging ; methods ; Persistent Vegetative State