Battaglini Luca, Mena Federica, Ghiani Andrea, Casco Clara, Melcher David, Ronconi Luca
Department of General Psychology, University of Padua, Padua, Italy.
Neuro.Vis. U.S. Laboratory, University of Padua, Padua, Italy.
Front Psychol. 2020 Jul 31;11:1765. doi: 10.3389/fpsyg.2020.01765. eCollection 2020.
We experience the world around us as a smooth and continuous flow. However, there is growing evidence that the stream of sensory inputs is not elaborated in an analog way but is instead organized in discrete or quasi-discrete temporal processing windows. These discrete windows are suggested to depend on rhythmic neural activity in the alpha (and theta) frequency bands, which in turn reflect changes in neural activity within, and coupling between, cortical areas. In the present study, we investigated a possible causal link between oscillatory brain activity in the alpha range (8-12 Hz) and the temporal resolution of visual perception, which determines whether sequential stimuli are perceived as distinct entities or combined into a single representation. To this aim, we employed a two-flash fusion task while participants received focal transcranial alternating current stimulation (tACS) in extra-striate visual regions including V5/MT of the right hemisphere. Our findings show that 10-Hz tACS, as opposed to a placebo (sham tACS), reduces the temporal resolution of perception, inducing participants to integrate the two stimuli into a unique percept more often. This pattern was observed only in the contralateral visual hemifield, providing further support for a specific effect of alpha tACS. The present findings corroborate the idea of a causal link between temporal windows of integration/segregation and oscillatory alpha activity in V5/MT and extra-striate visual regions. They also stimulate future research on possible ways to shape the temporal resolution of human vision in an individualized manner.
我们将周围的世界体验为一种平滑且连续的信息流。然而，越来越多的证据表明，感觉输入流并非以模拟方式进行精细加工，而是在离散或准离散的时间处理窗口中进行组织。这些离散窗口被认为依赖于α（和θ）频段的节律性神经活动，而这又反过来反映了皮质区域内神经活动的变化以及它们之间的耦合。在本研究中，我们调查了α波段（8 - 12赫兹）的振荡脑活动与视觉感知的时间分辨率之间可能存在的因果关系，视觉感知的时间分辨率决定了连续刺激是被视为不同的实体还是被整合为单一表征。为此，我们采用了双闪光融合任务，同时让参与者在包括右半球V5/MT的纹外视觉区域接受局部经颅交流电刺激（tACS）。我们的研究结果表明，与安慰剂（假tACS）相比，10赫兹的tACS降低了感知的时间分辨率，使参与者更频繁地将两个刺激整合为一个独特的感知。这种模式仅在对侧视觉半视野中观察到，为α tACS的特定效应提供了进一步支持。本研究结果证实了V5/MT和纹外视觉区域中整合/分离的时间窗口与振荡α活动之间存在因果关系的观点。它们还激发了未来关于以个性化方式塑造人类视觉时间分辨率的可能方法的研究。
