Changes in Frontal Band Power and Pupil Diameter Predict Performance During Motor Imagery Neurofeedback.

Neurofeedback (NF) offers potential for cognitive enhancement and brain rehabilitation, yet a substantial proportion of individuals fail to acquire self-regulation of brain activity. Task engagement, strongly linked to attentional focus and arousal, is a critical determinant of NF success. Frontal theta and alpha band oscillations, as well as pupil diameter and skin conductance responses are known to reflect attentional control, cognitive workload and arousal, all of which influence task performance. The present study investigates the relationship between frontal theta and alpha power, pupil diameter and skin conductance with performance during motor imagery NF training. By examining these multimodal physiological markers, we aimed at identifying reliable indicators of cognitive engagement and predictors of NF performance. Our findings indicate that fluctuations in NF performance are systematically associated with distinct psychophysiological changes within individuals, but also globally at a group level. Frontal theta synchronization, alpha desynchronization and pupil diameter were strongly related to NF performance. Notably, alpha desynchronization and pupil diameter emerged as significant predictors of the individual performance level, with stronger frontal alpha desynchronization and increased pupil diameter predicting higher performance. Our results suggest the potential of theta synchronization, alpha desynchronization and pupil diameter as dynamic markers of engagement and performance during NF sessions.