Research Group Experimental Oto-rhino-laryngology, Department of Neuroscience, Leuven Brain Institute, KU Leuven, Leuven, 3000, Belgium.
Leuven Brain Institute, KU Leuven, Leuven, 3000, Belgium.
Transl Psychiatry. 2024 Oct 28;14(1):456. doi: 10.1038/s41398-024-03158-6.
tDCS is widely assumed to cause neuromodulation via the electric field in the cortex acting directly on cortical neurons. However, recent evidence suggests that tDCS may indirectly influence brain activity through cranial nerve pathways, notably the trigeminal nerve, but these neuromodulatory pathways remain unexplored. To investigate the first stages in this potential pathway we developed an animal model to study the effect of trigeminal nerve direct current stimulation (TN-DCS) on neuronal activity in the principal sensory nucleus (NVsnpr) and the mesencephalic nucleus of the trigeminal nerve (MeV). We conducted experiments on twenty-four male Sprague Dawley rats (n = 10 NVsnpr, n = 10 MeV during anodic stimulation, and n = 4 MeV during cathodic stimulation). DC stimulation, ranging from 0.5 to 3 mA, targeted the trigeminal nerve's marginal branch. Concurrently, single-unit electrophysiological recordings were obtained using a 32-channel silicon probe, encompassing three 1-min intervals: pre, during, and post-stimulation. Xylocaine trigeminal nerve blockage served as a control. TN-DCS increased neuronal spiking activity in both NVsnpr and MeV, returning to baseline during the post-stimulation phase. The 3 mA DC stimulation of the blocked trigeminal nerve failed to induce increased spiking activity in the trigeminal nuclei. These findings provide empirical support for trigeminal nuclei modulation via TN-DCS, suggesting the cranial nerve pathways could play a role in mediating the tDCS effects in humans.
tDCS 被广泛认为通过作用于皮质神经元的皮层电场引起神经调节。然而，最近的证据表明，tDCS 可能通过颅神经通路（尤其是三叉神经）间接影响大脑活动，但这些神经调节途径仍未得到探索。为了研究这个潜在途径的最初阶段，我们开发了一种动物模型，研究三叉神经直流电刺激（TN-DCS）对主要感觉核（NVsnpr）和三叉神经中脑核（MeV）神经元活动的影响。我们对二十四只雄性 Sprague Dawley 大鼠进行了实验（n = 10 NVsnpr，n = 10 MeV 在阳极刺激期间，n = 4 MeV 在阴极刺激期间）。DC 刺激范围从 0.5 到 3 mA，针对三叉神经的边缘分支。同时，使用 32 通道硅探针进行单单元电生理记录，包括三个 1 分钟间隔：刺激前、刺激期间和刺激后。使用利多卡因三叉神经阻滞作为对照。TN-DCS 增加了 NVsnpr 和 MeV 中的神经元放电活动，并在刺激后阶段恢复到基线。阻断的三叉神经的 3 mA DC 刺激未能诱导三叉神经核中放电活动增加。这些发现为通过 TN-DCS 调节三叉神经核提供了经验支持，表明颅神经途径可能在介导 tDCS 对人类的影响中发挥作用。
