Piedimonte Alessandro, Benedetti Fabrizio, Carlino Elisa
Department of Neuroscience, National Institute of Neuroscience, University of Turin Medical School, Corso Raffaello 30, Turin, 10125, Italy.
Eur J Neurosci. 2015 Feb;41(4):492-7. doi: 10.1111/ejn.12806. Epub 2014 Dec 19.
Placebos have been found to affect a number of pathological processes and physiological functions through expectations of clinical improvement. Recently, the study of the placebo effect has moved from the clinical to the physical performance setting, wherein placebos can boost performance by increasing muscle work and by decreasing perceived exertion. However, nothing is known about the neurobiological underpinnings of this phenomenon. Here we show for the first time that a placebo, which subjects believed to be endurance-increasing caffeine, reduces fatigue by acting at the central level on the preparatory phase of movement. In fact, we recorded the readiness potential, which is the expression of the preparatory phase of movement at the level of the supplementary motor area, during repeated flexions of the index finger in a control group that did not receive any treatment and in a placebo group that received placebo caffeine. In the control group, as the number of flexions increased, both fatigue and readiness potential amplitude increased. By contrast, in the placebo group, as the number of flexions increased we found a decrease in perceived exertion along with no increase in readiness potential amplitude. This placebo-induced modulation of the readiness potential suggests that placebos reduce fatigue by acting centrally during the anticipatory phase of movement, thus emphasizing the important role of the central nervous system in the generation of fatigue.
人们发现，安慰剂可通过对临床改善的预期，影响多种病理过程和生理功能。最近，安慰剂效应的研究已从临床领域扩展至体能表现领域，在该领域中，安慰剂可通过增加肌肉做功和降低主观用力感来提高体能表现。然而，对于这一现象的神经生物学基础，我们却一无所知。在此，我们首次表明，一种被受试者认为是可增强耐力的咖啡因的安慰剂，通过作用于运动准备阶段的中枢水平来减轻疲劳。事实上，我们在未接受任何治疗的对照组和接受安慰剂咖啡因的安慰剂组中，记录了食指反复屈曲过程中的准备电位，准备电位是运动准备阶段在辅助运动区水平的表现。在对照组中，随着屈曲次数的增加，疲劳和准备电位幅值均增加。相比之下，在安慰剂组中，随着屈曲次数的增加，我们发现主观用力感下降，且准备电位幅值并未增加。这种安慰剂诱导的准备电位调节表明，安慰剂通过在运动预期阶段作用于中枢来减轻疲劳，从而强调了中枢神经系统在疲劳产生中的重要作用。
