The City College of the City University of New York, New York, New York, USA.
Brain Stimul. 2009 Oct;2(4):201-7, 207.e1. doi: 10.1016/j.brs.2009.03.005.
The spatial resolution of conventional transcranial direct current stimulation (tDCS) is considered to be relatively diffuse owing to skull dispersion. However, we show that electric fields may be clustered at distinct gyri/sulci sites because of details in tissue architecture/conductivity, notably cerebrospinal fluid (CSF). We calculated the cortical electric field/current density magnitude induced during tDCS using a high spatial resolution (1 mm3) magnetic resonance imaging (MRI)-derived finite element human head model; cortical gyri/sulci were resolved. The spatial focality of conventional rectangular-pad (7 x 5 cm2) and the ring (4 x 1) electrode configurations were compared. The rectangular-pad configuration resulted in diffuse (unfocal) modulation, with discrete clusters of electric field magnitude maxima. Peak-induced electric field magnitude was not observed directly underneath the pads, but at an intermediate lobe. The 4 x 1 ring resulted in enhanced spatial focality, with peak-induced electric field magnitude at the sulcus and adjacent gyri directly underneath the active electrode. Cortical structures may be focally targeted by using ring configurations. Anatomically accurate high-resolution MRI-based forward-models may guide the "rational" clinical design and optimization of tDCS.
传统经颅直流电刺激（tDCS）的空间分辨率被认为相对扩散，这是由于颅骨分散所致。然而，我们表明，由于组织结构/电导率的细节，特别是脑脊液（CSF），电场可能会在特定的脑回/脑沟部位聚集。我们使用高空间分辨率（1 毫米 3）的磁共振成像（MRI）衍生的有限元人头模型计算 tDCS 期间诱导的皮质电场/电流密度幅度；解决了皮质脑回/脑沟。比较了传统矩形垫（7 x 5 cm2）和环（4 x 1）电极配置的空间聚焦性。矩形垫配置导致弥散（无焦点）调制，具有电场幅度最大值的离散簇。未在垫下直接观察到峰值诱导的电场幅度，而是在中间叶。4 x 1 环增强了空间聚焦性，峰值诱导的电场幅度位于活动电极正下方的沟和相邻的回。可以通过使用环形配置有针对性地聚焦皮质结构。基于解剖精确的高分辨率 MRI 的正向模型可能指导 tDCS 的“合理”临床设计和优化。
