Mu oscillations and motor imagery performance: A reflection of success, not ability

Abstract

Motor imagery, or our ability to imagine movement without actually engaging in the action, has been an increasingly popular tool in rehabilitation settings. Understanding its neural underpinning is crucial for further development of new interventions. Using scalp electroencephalography (EEG), many studies have shown that mu oscillations (8-13 Hz), a variant of the alpha band recorded over the motor cortex electrodes, are involved in both the imagination and performance of movements; however, the exact relationship between mu oscillations and motor imagery is unclear. To further our understanding of the functional significance of mu oscillations and their role in both motor learning and motor performance, our study sought to investigate how suppression in mu oscillations varies during a motor imagery task according to both within subject imagery success and between subject imagery ability. We examined EEG activity while a large sample of participants performed an objective test of motor imagery ability (Test of Ability in Movement Imagery, TAMI). Results demonstrated that mu oscillatory activity significantly decreased during successful imagery trials as compared to unsuccessful ones. However, the extent of reduction in mu oscillations did not correlate with individual imagery ability. These results provide further support for the involvement of mu oscillations in motor behaviours and indicate that suppression in mu oscillations may serve as an important index for determining successful motor imagery performance within an individual. The processes that underlie this success are likely similar to those that underlie successful motor execution, given motor imagerys proposed functional equivalence to motor imagery.