Primary sensorimotor cortex activation with task-performance after fatiguing hand exercise
- 169 Downloads
We have compared functional MRI signals in primary sensorimotor cortex (SM1) during a paced motor task of each hand before and after unimanual (right hand) fatiguing exercise. Our aims were to determine whether the degree of activation is different when a motor task is performed after a fatiguing exercise, and whether there are any differences in activation between movement of the fatigued and non-fatigued hands. There was a significant reduction in the number of voxels activated in SM1 in the hemisphere contralateral to movement of both the fatigued hand (38±5 pre-exercise versus 21±3 post-exercise; P<0.05) and the non-fatigued hand (32±4 pre-exercise vs 18±4 post-exercise; P<0.05). There was no significant difference in the magnitude of the functional magnetic resonance imaging signal before or after exercise, however, the variance increased significantly after exercise (6.0±0.5 pre-exercise vs 7.3±0.6 post-exercise; P<0.01). Reduced functional activation in SM1 may reflect increased variability in the activation rather than a reduction in activation of cortical motor networks after fatigue.
KeywordsFatigue Functional MRI Motor cortex
We are grateful to Dr V Low (Head) and radiographers at the MRI Unit, Department of Radiology, Sir Charles Gairdner Hospital, for their support and assistance in carrying out these studies. Peter Clissa is thanked for technical advice. This study was supported by the Neuromuscular Foundation of Western Australia. NMB is a recipient of an Australian Postgraduate Award, Jean Rogerson Postgraduate Scholarship and 2004 Woodside Neurotrauma PhD Excellence Award.
- Benwell NM, Thickbroom GW, Sacco P, Hammond G, Byrnes ML, Mastaglia FL (2003) Changes in intracortical inhibition with fatigue of the hand. Proceedings of the Australian Neuroscience Society 14:O-06Google Scholar
- Gandevia SC, Allen GM, Butler JE, Taylor JL (1996) Supraspinal factors in human muscle fatigue: evidence for suboptimal output from the motor cortex. J Physiol (Lond) 490:529–536Google Scholar
- Taylor JL, Butler JE, Allen GM, Gandevia SC (1996) Changes in motor cortical excitability during human muscle fatigue. J Physiol (Lond) 490:519–528Google Scholar