Parazzini Marta, Fiocchi Serena, Ravazzani Paolo
National Research Council, Institute of Biomedical Engineering, ISIB-CNR, Milan, Italy.
Bioelectromagnetics. 2012 Sep;33(6):476-87. doi: 10.1002/bem.21708. Epub 2012 Feb 1.
Tinnitus is considered an auditory phantom percept. Recently, transcranial direct current stimulation (tDCS) has been proposed as a new approach for tinnitus treatment including, as potential targets of interest, either the temporal and temporoparietal cortex or prefrontal areas. This study investigates and compares the spatial distribution of the magnitude of the electric field and the current density in the brain tissues during tDCS of different brain targets. A numerical method was applied on a realistic human head model to calculate these field distributions in different brain structures, such as the cortex, white matter, cerebellum, hippocampus, medulla oblongata, pons, midbrain, thalamus, and hypothalamus. Moreover, the same distributions were evaluated along the auditory pathways. Results of this study show that tDCS of the left temporoparietal cortex resulted in a widespread diffuse distribution of the magnitude of the electric fields (and also of the current density) on an area of the cortex larger than the target brain region. On the contrary, tDCS of the dorsolateral prefrontal cortex resulted in a stimulation mainly concentrated on the target itself. Differences in the magnitude distribution were also found on the structures along the auditory pathways. A sensitivity analysis was also performed, varying the electrode position and the human head models. Accurate estimation of the field distribution during tDCS in different regions of the head could be valuable to better determine and predict efficacy of tDCS for tinnitus suppression.
耳鸣被认为是一种听觉幻觉。最近，经颅直流电刺激（tDCS）已被提议作为治疗耳鸣的一种新方法，其中颞叶和颞顶叶皮层或前额叶区域作为潜在的感兴趣靶点。本研究调查并比较了不同脑靶点进行tDCS时脑组织中电场强度和电流密度的空间分布。在一个逼真的人体头部模型上应用数值方法来计算不同脑结构（如皮层、白质、小脑、海马体、延髓、脑桥、中脑、丘脑和下丘脑）中的这些场分布。此外，还沿着听觉通路评估了相同的分布情况。本研究结果表明，左侧颞顶叶皮层的tDCS导致电场强度（以及电流密度）在皮层上的一个比目标脑区更大的区域广泛弥漫分布。相反，背外侧前额叶皮层的tDCS导致刺激主要集中在目标区域本身。在听觉通路上的结构中也发现了强度分布的差异。还进行了敏感性分析，改变电极位置和人体头部模型。准确估计头部不同区域进行tDCS时的场分布对于更好地确定和预测tDCS抑制耳鸣的疗效可能具有重要价值。
