Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy; Institute of Neurology, Department of Geriatrics, Neurosciences & Orthopaedics, Catholic University of Sacred Heart, Rome, Italy.
Laboratory of Electrophysiology for Translational neuroScience (LET'S) - ISTC - CNR, Department of Neuroscience, Fatebenefratelli Hospital, Rome, Italy; Department of Neuroscience and Imaging, G. d'Annunzio University of Chieti - Pescara, Italy.
Brain Stimul. 2015 May-Jun;8(3):555-60. doi: 10.1016/j.brs.2015.01.398. Epub 2015 Jan 14.
Among transcranial electric stimulation (tES) parameters, personalizing the electrode geometry might help overcome the individual variability of the induced effects.
OBJECTIVE/HYPOTHESIS: To test the need for electrode personalization, instead of a universal electrode for everyone, to induce neuromodulation effects on the bilateral primary motor cortex (M1) devoted to upper and lower limb representation.
By an ad-hoc neuronavigation procedure, we shaped the personalized electrode and positioned it matching the projection on the scalp of the individual central sulcus by a 2 cm strip, with total area of 35 cm(2). The non-personalized electrode, i.e., equal for all subjects, was a 2 cm wide strip size-matched with the personalized electrode but shaped on a standard model fitting the curve passing through C3-CZ-C4 sites of the electroencephalographic (EEG) 10-20 International System. To test neuromodulation electrode-dependent efficacy, we induced a 20 Hz sinusoidal modulated current (transcranial alternating current stimulation, tACS) because it produces online effects. We simultaneously collected left and right hand and leg motor potentials (MEP) that were evoked by a rounded transcranial magnetic stimulation (TMS) coil. Through each electrode we delivered both real and sham stimulations.
While cortical excitability during tACS increased during both the non-personalized and the personalized electrodes for the leg, the hand representation excitability enhancement was induced selectively when using the personalized electrode. The results were consistent bilaterally.
We documented that by using a personalized electrode it is possible to induce the neuromodulation of a predetermined extended cortical target, which did not occur with a non-personalized electrode. Our findings can help in building neuromodulation methods that might compensate for individual alterations across specific brain networks.
在经颅电刺激（tES）参数中，个性化电极几何形状可能有助于克服诱导效应的个体差异。
目的/假设：测试是否需要个性化电极，而不是为每个人使用通用电极，以在双侧初级运动皮层（M1）上诱导神经调节效应，这些电极专门用于上肢和下肢的代表区。
通过专门的神经导航程序，我们塑造了个性化电极，并将其与头皮上的个体中央沟投影相匹配，使用 2cm 宽的条状，总面积为 35cm²。非个性化电极，即所有受试者都相同，是一个 2cm 宽的条状，尺寸与个性化电极匹配，但形状基于符合脑电图（EEG）10-20 国际系统通过 C3-CZ-C4 点的曲线的标准模型。为了测试神经调节电极依赖性疗效，我们诱导了 20Hz 正弦调制电流（经颅交流电刺激，tACS），因为它产生在线效应。我们同时采集了由圆形经颅磁刺激（TMS）线圈诱发的左手和右手以及左腿和右腿运动电位（MEP）。通过每个电极，我们都进行了真实和假刺激。
虽然在非个性化和个性化电极下，腿部的 tACS 期间皮质兴奋性都增加，但仅当使用个性化电极时，手部代表区的兴奋性增强才被诱发。结果双侧一致。
我们记录到，通过使用个性化电极，可以诱导预定扩展皮质靶区的神经调节，而使用非个性化电极则不会发生这种情况。我们的发现有助于构建神经调节方法，这些方法可能会补偿特定脑网络中的个体变化。
