Transcranial direct current stimulation (tDCS) has great potential to modulate cortical excitability and further facilitate visual function or rehabilitation. However, tDCS modulation effects are largely variable, possibly because of the individual differences in initial performance. The present study investigated the influence of the initial performance on contrast sensitivity function (CSF) following tDCS. Fifty healthy participants were randomly assigned to three groups: anodal, cathodal and sham stimulation. The CSF was measured through a grating detection task before and immediately after tDCS. Active and reference electrodes were applied to the primary occipital cortex (Oz) and the middle of the head (Cz) for 20 min with an intensity of 1.5 mA, respectively. Compared with sham stimulation, anodal or cathodal stimulation had no effect on the area under the log CSF (AULCSF) or contrast sensitivity (CS) of various spatial frequencies at the group level. However, a negative relationship was found between initial performance and the AULCSF change (or CS change at a spatial of frequency 8 c/°) after the application of anodal tDCS, indicating that the degree of change was dependent on initial performance, with greater gains observed for those with poorer initial performance. Initial performance modulated the effect of anodal tDCS over the Oz on the CSF, indicating that the Oz plays a crucial role in visual function. These results contribute to a deep understanding of the mechanisms of tDCS and to the design of more precise and efficient personalized simulation approaches based on individual differences.

经颅直流电刺激（tDCS）具有调节皮层兴奋性并进一步促进视觉功能或康复的巨大潜力。但是，tDCS调制效果在很大程度上是可变的，这可能是由于初始性能的个体差异所致。本研究调查了tDCS后初始性能对对比敏感度函数（CSF）的影响。将五十名健康参与者随机分为三组：阳极刺激，阴极刺激和假刺激。在tDCS之前和之后，通过光栅检测任务测量了CSF。将主动电极和参比电极分别以1.5 mA的强度施加到枕骨初级皮质（Oz）和头部中部（Cz）20分钟。与假刺激相比，阳极或阴极刺激对组水平上各种空间频率的log CSF下面积（AULCSF）或对比敏感度（CS）没有影响。但是，在使用阳极tDCS之后，初始性能与AULCSF变化（或在频率为8 c /°的空间上的CS变化）之间存在负相关关系，这表明变化程度取决于初始性能，且增益更大观察那些初期表现较差的人。最初的表现调节了Ot对CSF的阳极tDCS的影响，表明Oz在视觉功能中起着至关重要的作用。这些结果有助于深入了解tDCS的机制，并有助于根据个人差异设计更精确，更有效的个性化仿真方法。