Decoding Musical Neural Activity in Patients With Disorders of Consciousness Through Self-Supervised Contrastive Domain Generalization

Identifying the brain responses of patients with disorders of consciousness (DOCs), which include comas, vegetative states (VSs, also called unresponsive wakefulness syndrome (UWS)) and minimally conscious states (MCSs), based on electroencephalography (EEG) has important clinical diagnosis implications. However, due to impaired motor and cognitive abilities, patients with DOCs may not be able to express their feelings and their brain responses to different stimuli, making it difficult to correctly label data. EEG classification algorithms trained with these data cannot make reliable classifications and predictions for clinical diagnosis purposes. To identify the brain responses produced for different types of stimuli in patients with DOCs, we proposed a self-supervised contrastive domain generalization framework (SSCDG) for cross-subject EEG classification. The model was first trained with healthy-subject EEG data induced by different stimuli to learn their corresponding unsupervised representations. Then, we used these representations to train a classifier to predict the emotional states of patients with DOCs under the corresponding stimuli. SSCDG was first evaluated on the SEED dataset, and it achieved an accuracy of 87.6%, which was 1.1% higher than that of the state-of-the-art (SOTA) approaches. Moreover, the SSCDG method was utilized to categorize EEG data acquired from seventeen DOC patients, including eleven in a UWS state and six in an MCS state, with seven patients demonstrating notable accuracy in three-class EEG classification tasks. The SSCDG results indicated that the seven patients with DOCs may have shown classifiable EEG responses to the presented stimuli.