Clayton Michael S, Yeung Nick, Cohen Kadosh Roi
Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
Front Neurosci. 2018 Feb 13;12:67. doi: 10.3389/fnins.2018.00067. eCollection 2018.
Neural oscillations in the alpha band (7-13 Hz) are commonly associated with disengagement of visual attention. However, recent studies have also associated alpha with processes of attentional control and stability. We addressed this issue in previous experiments by delivering transcranial alternating current stimulation at 10 Hz over posterior cortex during visual tasks (alpha tACS). As this stimulation can induce reliable increases in EEG alpha power, and given that performance on each of our visual tasks was negatively associated with alpha power, we assumed that alpha tACS would reliably impair visual performance. However, alpha tACS was instead found to prevent both deteriorations and improvements in visual performance that otherwise occurred during sham & 50 Hz tACS. Alpha tACS therefore appeared to exert a stabilizing effect on visual attention. This hypothesis was tested in the current, pre-registered experiment by delivering alpha tACS during a task that required rapid switching of attention between motion, color, and auditory subtasks. We assumed that, if alpha tACS stabilizes visual attention, this stimulation should make it harder for people to switch between visual tasks, but should have little influence on transitions between auditory and visual subtasks. However, in contrast to this prediction, we observed no evidence of impairments in visuovisual vs. audiovisual switching during alpha vs. control tACS. Instead, we observed a trend-level reduction in visuoauditory switching accuracy during alpha tACS. analyses showed no effects of alpha tACS in response time variability, diffusion model parameters, or on performance of repeat trials. EEG analyses also showed no effects of alpha tACS on endogenous or stimulus-evoked alpha power. We discuss possible explanations for these results, as well as their broader implications for current efforts to study the roles of neural oscillations in cognition using tACS.
α波段（7-13赫兹）的神经振荡通常与视觉注意力的脱离有关。然而，最近的研究也将α与注意力控制和稳定性过程联系起来。我们在之前的实验中通过在视觉任务期间对后皮质施加10赫兹的经颅交流电刺激（α-tACS）来解决这个问题。由于这种刺激可以可靠地增加脑电图α波功率，并且鉴于我们每个视觉任务的表现都与α波功率呈负相关，我们假设α-tACS会可靠地损害视觉表现。然而，相反地，发现α-tACS可以防止在伪刺激和50赫兹tACS期间原本会出现的视觉表现的恶化和改善。因此，α-tACS似乎对视觉注意力产生了稳定作用。在当前预先注册的实验中，通过在一项需要在运动、颜色和听觉子任务之间快速切换注意力的任务期间施加α-tACS来检验这一假设。我们假设，如果α-tACS能稳定视觉注意力，这种刺激应该会使人们在视觉任务之间切换变得更加困难，但对听觉和视觉子任务之间的转换影响很小。然而，与这一预测相反，我们在α-tACS与对照tACS期间未观察到视觉与视觉切换或听觉与视觉切换受损的证据。相反，我们观察到在α-tACS期间视觉与听觉切换准确性有趋势性降低。分析表明，α-tACS对反应时间变异性、扩散模型参数或重复试验的表现没有影响。脑电图分析也表明，α-tACS对内生性或刺激诱发的α波功率没有影响。我们讨论了这些结果的可能解释，以及它们对当前使用tACS研究神经振荡在认知中的作用的努力的更广泛影响。
