Centro Clinico per la Neurostimolazione, le Neurotecnologie ed i Disordini del Movimento, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
Cerebellum. 2013 Aug;12(4):485-92. doi: 10.1007/s12311-012-0436-9.
Neuroimaging studies suggest that the cerebellum contributes to human cognitive processing, particularly procedural learning. This type of learning is often described as implicit learning and involves automatic, associative, and unintentional learning processes. Our aim was to investigate whether cerebellar transcranial direct current stimulation (tDCS) influences procedural learning as measured by the serial reaction time task (SRTT), in which subjects make speeded key press responses to visual cues. A preliminary modeling study demonstrated that our electrode montage (active electrode over the cerebellum with an extra-cephalic reference) generated the maximum electric field amplitude in the cerebellum. We enrolled 21 healthy subjects (aged 20-49 years). Participants did the SRTT, a visual analogue scale and a visual attention task, before and 35 min after receiving 20-min anodal and sham cerebellar tDCS in a randomized order. To avoid carry-over effects, experimental sessions were held at least 1 week apart. For our primary outcome measure (difference in RTs for random and repeated blocks) anodal versus sham tDCS, RTs were significantly slower for sham tDCS than for anodal cerebellar tDCS (p = 0.04), demonstrating that anodal tDCS influenced implicit learning processes. When we assessed RTs for procedural learning across the one to eight blocks, we found that RTs changed significantly after anodal stimulation (interaction "time" × "blocks 1/8": anodal, p = 0.006), but after sham tDCS, they remained unchanged (p = 0.094). No significant changes were found in the other variables assessed. Our finding that anodal cerebellar tDCS improves an implicit learning type essential to the development of several motor skills or cognitive activity suggests that the cerebellum has a critical role in procedural learning. tDCS could be a new tool for improving procedural learning in daily life in healthy subjects and for correcting abnormal learning in neuropsychiatric disorders.
神经影像学研究表明，小脑有助于人类认知加工，特别是程序性学习。这种学习通常被描述为内隐学习，涉及自动、联想和无意识的学习过程。我们的目的是研究小脑经颅直流电刺激（tDCS）是否会影响程序性学习，这可以通过序列反应时间任务（SRTT）来测量，在该任务中，被试对视觉线索做出快速按键反应。一项初步建模研究表明，我们的电极布置（在小脑上放置活动电极，外加颅外参考）在小脑内产生最大电场幅度。我们招募了 21 名健康受试者（年龄 20-49 岁）。参与者在接受 20 分钟的阳极和假小脑 tDCS 后，以随机顺序在之前和 35 分钟后完成 SRTT、视觉模拟量表和视觉注意力任务。为了避免交叉效应，实验间隔至少 1 周。对于我们的主要结果测量（随机和重复块之间 RT 的差异），与假 tDCS 相比，阳极 tDCS 使 RT 显著变慢（p=0.04），表明阳极 tDCS 影响了内隐学习过程。当我们评估 1 到 8 个块的程序性学习 RT 时，我们发现阳极刺激后 RT 发生了显著变化（交互“时间”ד块 1/8”：阳极，p=0.006），但假 tDCS 后 RT 保持不变（p=0.094）。评估的其他变量没有发现显著变化。我们发现阳极小脑 tDCS 改善了对几种运动技能或认知活动的发展至关重要的内隐学习类型，这表明小脑在程序性学习中起着关键作用。tDCS 可能成为改善健康受试者日常生活中程序性学习和纠正神经精神障碍中异常学习的新工具。
