Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, 20246, Germany.
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, 20246, Germany.
Brain Stimul. 2022 Jan-Feb;15(1):244-253. doi: 10.1016/j.brs.2022.01.001. Epub 2022 Jan 3.
Visual phenomena like brightness illusions impressively demonstrate the highly constructive nature of perception. In addition to physical illumination, the subjective experience of brightness is related to temporal neural dynamics in visual cortex.
Here, we asked whether biasing the temporal pattern of neural excitability in visual cortex by transcranial alternating current stimulation (tACS) modulates brightness perception of concurrent rhythmic visual stimuli.
Participants performed a brightness discrimination task of two flickering lights, one of which was targeted by same-frequency electrical stimulation at varying phase shifts. tACS was applied with an occipital and a periorbital active control montage, based on simulations of electrical currents using finite element head models.
Experimental results reveal that flicker brightness perception is modulated dependent on the phase shift between sensory and electrical stimulation, solely under occipital tACS. Phase-specific modulatory effects by tACS were dependent on flicker-evoked neural phase stability at the tACS-targeted frequency, recorded prior to electrical stimulation. Further, the optimal timing of tACS application leading to enhanced brightness perception was correlated with the neural phase delay of the cortical flicker response.
Our results corroborate the role of temporally coordinated neural activity in visual cortex for brightness perception of rhythmic visual input in humans. Phase-specific behavioral modulations by tACS emphasize its efficacy to transfer perceptually relevant temporal information to the cortex. These findings provide an important step towards understanding the basis of visual perception and further confirm electrical stimulation as a tool for advancing controlled modulations of neural activity and related behavior.
亮度错觉等视觉现象令人印象深刻地展示了知觉的高度构建性质。除了物理照明外，主观的亮度体验还与视觉皮层中的时间神经动力学有关。
在这里，我们通过经颅交流电刺激（tACS）来询问是否改变视觉皮层中神经兴奋性的时间模式是否会调节同时呈现的节奏性视觉刺激的亮度感知。
参与者执行了一项闪烁灯光的亮度辨别任务，其中一个灯光受到频率相同的电刺激，相位偏移不同。tACS 应用于枕部和眶周主动控制的组合，基于使用有限元头部模型的电流模拟。
实验结果表明，仅在枕部 tACS 下，闪烁亮度感知会根据感觉和电刺激之间的相位偏移进行调制。tACS 的相位特异性调制效应取决于在电刺激之前记录的针对 tACS 目标频率的闪烁诱发神经相位稳定性。此外，导致增强亮度感知的最佳 tACS 应用时机与皮层闪烁反应的神经相位延迟相关。
我们的结果证实了时间协调的神经活动在人类对节奏性视觉输入的亮度感知中的作用。tACS 的相位特异性行为调制强调了它将与感知相关的时间信息传递到皮层的功效。这些发现为理解视觉感知的基础提供了重要的一步，并进一步证实了电刺激作为一种工具，可用于对神经活动和相关行为进行受控调节。
