Di Rienzo Franck, Guillot Aymeric, Daligault Sébastien, Delpuech Claude, Rode Gilles, Collet Christian
a CRIS (EA 647), Mental and Motor Performance, University Claude Bernard Lyon 1 , Villeurbanne Cedex , France.
Neurocase. 2014;20(5):524-39. doi: 10.1080/13554794.2013.826685. Epub 2013 Sep 2.
The neurophysiological substrates underlying motor imagery are now well established. However, the neural processes of motor inhibition while mentally rehearsing an action are poorly understood. This concern has received limited experimental investigations leading to divergent conclusions. Whether motor command suppression is mediated by specific brain structures or by intracortical facilitation/inhibition is a matter of debate. Interestingly, although motor commands are inhibited during motor imagery (MI) in healthy participants, spinal cord injury may result in weakened motor inhibition. Using magentoencephalography, we observed that mental and actual execution of a goal-directed pointing task elicited similar primary motor cortex activation in a C6-C7 quadriplegic patient, thus confirming the hypothesis of weakened motor inhibition during MI. In an age-matched healthy control participant, however, primary motor area activation during MI was significantly reduced compared to physical practice. Brain activation during actual movement resulted in enhanced recruitment of premotor areas in the patient. In the healthy participant, we found functional relationships between the primary motor area and peri-rolandic sites including the primary sensory area and the supplementary motor area during MI. This neural network was not activated when the quadriplegic patient performed MI. We assume that the primary sensory area and the supplementary motor area may be part of a functional network underlying motor inhibition during MI. These data provide insights into brain function changes due to neuroplasticity after spinal cord injury and evidence cortical substrates underlying weakened motor inhibition during MI after deafferentation and deefferentation.
运动想象背后的神经生理基质现已明确。然而，在进行动作心理演练时运动抑制的神经过程却知之甚少。这一问题受到的实验研究有限，得出的结论也不尽相同。运动指令抑制是由特定脑结构介导，还是由皮质内易化/抑制介导，仍是一个有争议的问题。有趣的是，尽管在健康参与者的运动想象（MI）过程中运动指令会受到抑制，但脊髓损伤可能会导致运动抑制减弱。通过脑磁图，我们观察到在一名C6 - C7四肢瘫痪患者中，目标导向性指向任务的心理演练和实际执行引发了类似的初级运动皮层激活，从而证实了运动想象过程中运动抑制减弱的假设。然而，在一名年龄匹配的健康对照参与者中，与实际练习相比，运动想象期间初级运动区的激活明显减少。患者在实际运动期间的脑激活导致运动前区的募集增强。在健康参与者中，我们发现在运动想象期间初级运动区与包括初级感觉区和辅助运动区在内的中央沟周围区域之间存在功能关系。当四肢瘫痪患者进行运动想象时，这个神经网络并未被激活。我们认为初级感觉区和辅助运动区可能是运动想象期间运动抑制潜在功能网络的一部分。这些数据为脊髓损伤后神经可塑性导致的脑功能变化提供了见解，并为去传入和去传出后运动想象期间运动抑制减弱的皮质基质提供了证据。
