State-Dependent tACS Effects Reveal the Potential Causal Role of Prestimulus Alpha Traveling Waves in Visual Contrast Detection

• Published in: The Journal of neuroscience Vol. 44; no. 27; p. e2023232024
• Main Authors: Wei, Jinwen, Alamia, Andrea, Yao, Ziqing, Huang, Gan, Li, Linling, Liang, Zhen, Zhang, Li, Zhou, Changsong, Song, Zhenxi, Zhang, Zhiguo
• Format: Journal Article
• Language: English
• Published: United States Society for Neuroscience 03.07.2024
• Subjects: Adult; Alpha Rhythm - physiology; Contrast Sensitivity - physiology; Double-Blind Method; Electroencephalography - methods; Female; Humans; Life Sciences; Male; Mental Fatigue - physiopathology; Neurons and Cognition; Photic Stimulation - methods; Transcranial Direct Current Stimulation - methods; Visual Perception - physiology; Young Adult; tACS; traveling waves; visual contrast detection; mental fatigue; state-dependent effect; alpha oscillations
• ISSN: 0270-6474; 1529-2401; 1529-2401
• DOI: 10.1523/JNEUROSCI.2023-23.2024

The intricate relationship between prestimulus alpha oscillations and visual contrast detection variability has been the focus of numerous studies. However, the causal impact of prestimulus alpha traveling waves on visual contrast detection remains largely unexplored. In our research, we sought to discern the causal link between prestimulus alpha traveling waves and visual contrast detection across different levels of mental fatigue. Using electroencephalography alongside a visual detection task with 30 healthy adults (13 females; 17 males), we identified a robust negative correlation between prestimulus alpha forward traveling waves (FTWs) and visual contrast threshold (VCT). Inspired by this correlation, we utilized 45/−45° phase-shifted transcranial alternating current stimulation (tACS) in a sham-controlled, double-blind, within–subject experiment with 33 healthy adults (23 females; 10 males) to directly modulate these alpha traveling waves. After the application of 45° phase-shifted tACS, we observed a substantial decrease in FTW and an increase in backward traveling waves, along with a concurrent increase in VCT, compared with the sham condition. These changes were particularly pronounced under a low fatigue state. The findings of state-dependent tACS effects reveal the potential causal role of prestimulus alpha traveling waves in visual contrast detection. Moreover, our study highlights the potential of 45/−45° phase-shifted tACS in cognitive modulation and therapeutic applications.