Bifocal alpha-band tACS modulates temporal sampling in visual perception

IF 4.5 2区医学 Q1 NEUROIMAGING

NeuroImage Pub Date : 2025-09-19 DOI:10.1016/j.neuroimage.2025.121474

Alessia Santoni , Giuseppe Di Dona , Riccardo Gironi , Sara Stottmeier , Luca Battaglini , Luca Ronconi

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引用次数: 0

Abstract

Alpha oscillations (7–13 Hz) have been historically considered to shape temporal sampling processes in the visual modality, with faster alpha frequencies linked to finer temporal resolution. However, evidence is mostly correlational, and findings are not always replicated. Here, we investigated the role of alpha oscillations in temporal sampling using transcranial alternating current stimulation (tACS) and electroencephalography (EEG). Over three consecutive blocks, bilateral high-definition tACS was applied over extra-striate visual areas including V5/MT at either the individual alpha frequency (IAF), IAF+2, or IAF-2 Hz while participants performed a two flash fusion task. In line with previous findings, baseline resting-state IAF correlated with temporal segregation accuracy, with higher IAF predicting better segregation ability. Importantly, stimulation at IAF+2 Hz improved temporal segregation accuracy, whereas IAF-2 Hz decreased performance. This effect was specific for stimuli in the right hemifield, highlighting important hemispheric differences in alpha-mediated visual temporal sampling. Following stimulation, EEG data revealed no shift in the IAF and a decrease of alpha power independently from stimulation condition. Nonetheless, specifically for the IAF+2 stimulation, we observed a modulation of the aperiodic exponent of the power spectrum, indicating possible changes in cortical excitability as a short-term plasticity mechanism that persists beyond online tACS effects. Taken together, these results corroborate the role of alpha oscillations in defining temporal sampling processes and add novel evidence on the neurophysiological effects of tACS.

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双焦点α波段tACS调节视觉感知中的时间采样。

阿尔法振荡（7-13赫兹）历来被认为是在视觉模态中塑造时间采样过程，更快的阿尔法频率与更精细的时间分辨率有关。然而，证据大多是相关的，研究结果并不总是被复制。在这里，我们使用经颅交流电刺激（tACS）和脑电图（EEG）研究了α振荡在时间采样中的作用。在三个连续的区块中，双侧高清晰度tACS应用于纹外视觉区域，包括V5/MT，在个人α频率（IAF）， IAF+2或IAF-2 Hz，同时参与者执行两次闪光融合任务。与先前的研究结果一致，基线静息状态IAF与时间分离精度相关，更高的IAF预示着更好的分离能力。重要的是，IAF+2 Hz的刺激提高了时间隔离的准确性，而IAF-2 Hz则降低了性能。这种效应是特定于右半脑区的刺激，突出了在α介导的视觉时间采样中重要的半球差异。刺激后，脑电图数据显示IAF没有变化，α功率的下降与刺激条件无关。尽管如此，特别是对于IAF+2刺激，我们观察到功率谱的非周期指数的调制，这表明皮质兴奋性的变化可能是一种短期可塑性机制，持续存在于在线tACS效应之外。综上所述，这些结果证实了α振荡在定义时间采样过程中的作用，并为tACS的神经生理效应提供了新的证据。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

NeuroImage 医学-核医学

CiteScore

11.30

自引率

10.50%

发文量

809

审稿时长

63 days

期刊介绍： NeuroImage, a Journal of Brain Function provides a vehicle for communicating important advances in acquiring, analyzing, and modelling neuroimaging data and in applying these techniques to the study of structure-function and brain-behavior relationships. Though the emphasis is on the macroscopic level of human brain organization, meso-and microscopic neuroimaging across all species will be considered if informative for understanding the aforementioned relationships.