Dipartimento di Neuroscienze, Sezione Neurologia and Neurofisiologia Clinica, Azienda Ospedaliera Universitaria Senese, Siena, Italy.
Restor Neurol Neurosci. 2012;30(6):481-9. doi: 10.3233/RNN-2012-120241.
To investigate whether repeated sessions of motor imagery and action observation modulate corticospinal excitability (CE) over time, whether these processes are susceptible of any training effect and if such effect might be different for the dominant and non dominant hemisphere.
11 subjects underwent three sessions, spaced 5-7 days, of single-pulse Transcranial Magnetic Stimulation (TMS) of right and left primary motor cortex. Subjects were asked to imagine or observe pinch-grip actions with either hand. Motor evoked potentials (MEPs) were recorded bilaterally from the First Dorsal Interosseus muscle (FDI), acting as main agonist during precision grip.
Motor imagery consistently enhanced CE with respect to action observation, regardless of hemispheric lateralization and of separate testing sessions. However, motor imagery increased CE only when measured over the non-dominant hemisphere, during the third session with respect to the first one. The increase of CE induced by action observation in the first session was not further modified throughout the remaining two sessions, in either hemisphere.
Results suggest that motor imagery is sustained by a cortical network susceptible to training effects only for the non-dominant hemisphere. Such an effect was lacking for action observation, likely because of the innateness of these mechanisms. Results might have implications for rehabilitative purposes.
研究重复进行运动想象和动作观察是否会随着时间的推移而调节皮质脊髓兴奋性（CE），这些过程是否容易受到任何训练效果的影响，如果这种效果可能因优势半球和非优势半球而不同。
11 名受试者接受了三次单脉冲经颅磁刺激（TMS）治疗，刺激右侧和左侧初级运动皮层，间隔 5-7 天。要求受试者用双手想象或观察捏夹动作。第一背侧骨间肌（FDI）双侧记录运动诱发电位（MEP），作为精细抓握时的主要主动肌。
运动想象相对于动作观察始终增强了 CE，无论半球偏侧性和单独的测试会话如何。然而，只有在非优势半球进行第三次测试时，运动想象才会增加 CE，与第一次测试相比。在第一会话中通过动作观察引起的 CE 增加在剩余的两个会话中，在任一半球中都没有进一步改变。
结果表明，运动想象是由一个皮质网络维持的，该网络仅对非优势半球具有训练效果。对于动作观察，这种效果不存在，可能是因为这些机制是天生的。结果可能对康复目的具有重要意义。
