Distinct brain network organization in asynchronous and synchronous motor observation and motor imagery: evidence from EEG functional connectivity, phase-amplitude coupling, and decoding

Motor observation and motor imagery (MOMI) has been increasingly utilized in motor learning and neurorehabilitation research; however, it remains unclear whether different temporal arrangements of observation and imagery are reflected in distinct brain network organization. Therefore, the present study investigated whether asynchronous and synchronous MOMI exhibit distinct network-level patterns during motor simulation. To isolate the effect of temporal organization while maintaining a constant motor task context, participants performed a basketball set-shot task, allowing comparison among asynchronous MOMI (A-MOMI), synchronous MOMI (S-MOMI), and motor imagery (MI). Phase-locking value (PLV)-based functional connectivity analyses revealed significant condition-related differences, predominantly within the theta, alpha, and beta frequency bands. Specifically, MI exhibited stronger theta-band functional connectivity during the early phase of the task, whereas A-MOMI demonstrated more sustained enhancement of alpha-band connectivity during the middle and later phases. Furthermore, coupling between theta phase and 12-16 Hz amplitude was stronger in A-MOMI compared to both S-MOMI and MI. Decoding analysis further indicated moderate separability among the three conditions, yielding an overall classification accuracy of 69.61%. A-MOMI achieved the highest classification accuracy (79.41%), followed by MI (73.53%) and S-MOMI (55.88%), reflecting differential discriminability among the conditions. Collectively, these findings provide network-level evidence that the temporal organization of observation and imagery shapes MOMI-related brain network organization, with implications for optimizing motor training protocols and EEG-based assessments of motor simulation states.