Er 6 UPMC, Service de Médecine Physique et Réadaptation, Hôpital Pitié Salpêtrière, 75013 Paris, France.
J Physiol. 2011 Jun 1;589(Pt 11):2813-26. doi: 10.1113/jphysiol.2011.205161. Epub 2011 Apr 18.
In recent years, two techniques have become available for the non-invasive stimulation of human motor cortex: transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). The effects of TMS and tDCS when applied over motor cortex should be considered with regard not only to cortical circuits but also to spinal motor circuits. The different modes of action and specificity of TMS and tDCS suggest that their effects on spinal network excitability may be different from that in the cortex. Until now, the effects of tDCS on lumbar spinal network excitability have never been studied. In this series of experiments, on healthy subjects, we studied the effects of anodal tDCS over the lower limb motor cortex on (i) reciprocal Ia inhibition projecting from the tibialis anterior muscle (TA) to the soleus (SOL), (ii) presynaptic inhibition of SOL Ia terminals, (iii) homonymous SOL recurrent inhibition, and (iv) SOL H-reflex recruitment curves. The results show that anodal tDCS decreases reciprocal Ia inhibition, increases recurrent inhibition and induces no modification of presynaptic inhibition of SOL Ia terminals and of SOL-H reflex recruitment curves. Our results indicate therefore that the effects of tDCS are the opposite of those previously described for TMS on spinal network excitability. They also indicate that anodal tDCS induces effects on spinal network excitability similar to those observed during co-contraction suggesting that anodal tDCS activates descending corticospinal projections mainly involved in co-contractions.
近年来，出现了两种用于非侵入性刺激人类运动皮层的技术：经颅磁刺激（TMS）和经颅直流电刺激（tDCS）。当 TMS 和 tDCS 应用于运动皮层时，不仅要考虑皮层回路，还要考虑脊髓运动回路。TMS 和 tDCS 的不同作用机制和特异性表明，它们对脊髓网络兴奋性的影响可能与皮层不同。到目前为止，tDCS 对腰椎网络兴奋性的影响从未被研究过。在这一系列实验中，我们在健康受试者中研究了下肢运动皮层阳极 tDCS 对（i）来自胫骨前肌（TA）到比目鱼肌（SOL）的反向 Ia 抑制，（ii）SOL Ia 末梢的突触前抑制，（iii）同形同位抑制，和（iv）SOL H 反射募集曲线的影响。结果表明，阳极 tDCS 降低了反向 Ia 抑制，增加了同形同位抑制，并且没有改变 SOL Ia 末梢的突触前抑制和 SOL-H 反射募集曲线。因此，我们的结果表明，tDCS 的作用与 TMS 先前描述的脊髓网络兴奋性相反。它们还表明，阳极 tDCS 对脊髓网络兴奋性的影响类似于在协同收缩期间观察到的影响，这表明阳极 tDCS 主要激活涉及协同收缩的下行皮质脊髓投射。
