Brain Function, Motor Imagery

Human brain is a huge system with the most complex structure. As the human beings evoluting, human brain is continuously evoluting. Its function is enriched dramatically, and has become the most complicated staff. Brain imaging is one of the youngest and the most rapidly developing scientific fields. It emerges at the intersection of several of well-established disciplines.Motor imagery, defined as the mental rehearsal of motor movement without any overt body movements, has been demonstrated to play a very important role in training for athletes and musicians, and also in the recovery of motor abilities in patients with movement disorders.This paper mainly focused on the study of motor imagery based on functional magnetic resonance imaging, analyzed the brain activation during motor imagery. Further, we used Granger causality mapping to explore the effective connectivity of the brain during motor imagery.Some aspects of this dissertation have been put forward:1. Study of the brain activation during motor imagery. A complex finger tapping imagery and execution experiment was designed and two methods, SPM based on Generalized Linear Model and Independent Component Analysis, were employed to test the brain activation during MI. The results show that during MI, brain activation exists mainly in the supplementary motor area (SMA) and precentral area where the dorsal premotor area (PMd) and the primary motor area (M1) mainly located; and some activation can be also observed in the primary and secondary somatosensory cortex (S1), the inferior parietal lobule (IPL) and the superior parietal lobule (SPL). Additionally, more brain activation can be observed during left-hand MI than during right-hand MI, this difference probably is caused by asymmetry of brain.2. Study of the effective connectivity of brain during motor imagery. Selecting the SMA as the region of interest, we used Granger causality mapping (GCM) to explore effective connectivity in the brain during motor imagery. Our results showed that more brain regions show effective connections to the SMA during right-hand motor imagery than during left-hand motor imagery, while the strength of casual influence during left-hand motor imagery was stronger than that of right-hand motor imagery. We further found forward and backward effective connectivity between the SMA and three regions including the bilateral dorsal premotor area (PMd), the contralateral primary and secondary somatosensory cortex (S1), and the primary motor cortex (M1) during motor imagery, which may indicate how the brain regions are interactivated.