A Trimodal Study on Hypoxia Adaptation: Promotion of Cerebral Functional Connectivity and Decrement of Neuromuscular Efficiency

This study employed a multimodal acquisition system comprising EEG, EMG, and fNIRS modules. Participants were fitted with a 64-channel dry EEG cap for the measurement of cortical electrical activity. Surface EMG electrodes were attached to three muscle groups: the right biceps brachii, the flexor digitorum profundus of the forearm, and the gastrocnemius muscle, to record muscle activation signals. Simultaneously, fNIRS probes were positioned on the participants' foreheads to monitor cerebral hemodynamic responses.

The experimental paradigm was divided into two tasks: motor execution (ME) and motor imagery (MI). During the ME task, participants performed 15 trials of actual movements, whereas the MI task involved 60 trials of imagined movements. Each trial randomly presented one of three stimuli-left-hand clenching, right-hand clenching, or bilateral heel raising-with an equal distribution of the three movement types across the session. The order of stimuli was randomized to prevent prediction bias.