Institute of Neuroscience and Psychology, University of Glasgow, 58 Hillhead Street, Glasgow G12 8QB, UK.
Curr Biol. 2012 May 8;22(9):807-13. doi: 10.1016/j.cub.2012.03.025. Epub 2012 Apr 12.
An event in one sensory modality can phase reset brain oscillations concerning another modality. In principle, this may result in stimulus-locked periodicity in behavioral performance. Here we considered this possible cross-modal impact of a sound for one of the best-characterized rhythms arising from the visual system, namely occipital alpha-oscillations (8-14 Hz). We presented brief sounds and concurrently recorded electroencephalography (EEG) and/or probed visual cortex excitability (phosphene perception) through occipital transcranial magnetic stimulation (TMS). In a first, TMS-only experiment, phosphene perception rate against time postsound showed a periodic pattern cycling at ~10 Hz phase-aligned to the sound. In a second, combined TMS-EEG experiment, TMS-trials reproduced the cyclical phosphene pattern and revealed a ~10 Hz pattern also for EEG-derived measures of occipital cortex reactivity to the TMS pulses. Crucially, EEG-data from intermingled trials without TMS established cross-modal phase-locking of occipitoparietal alpha oscillations. These independently recorded variables, i.e., occipital cortex excitability and reactivity and EEG phase dynamics, were significantly correlated. This shows that cross-modal phase locking of oscillatory visual cortex activity can arise in the human brain to affect perceptual and EEG measures of visual processing in a cyclical manner, consistent with occipital alpha oscillations underlying a rapid cycling of neural excitability in visual areas.
一种感觉模态中的事件可以使另一种感觉模态的脑振荡相位重置。原则上，这可能导致行为表现中的刺激锁定周期性。在这里，我们考虑了来自视觉系统的最佳特征之一节律，即枕部 alpha 振荡（8-14 Hz），对声音的这种可能的跨模态影响。我们呈现了短暂的声音，并同时通过枕部经颅磁刺激（TMS）记录脑电图（EEG）和/或探测视觉皮层兴奋性（闪光感知）。在第一个仅 TMS 的实验中，针对时间 postsound 的闪光感知率显示出约 10 Hz 的周期性模式，与声音相位对齐。在第二个，结合 TMS-EEG 的实验中，TMS 试验再现了周期性的闪光模式，并揭示了 EEG 衍生的枕部皮层对 TMS 脉冲反应的约 10 Hz 模式。至关重要的是，没有 TMS 的混合试验的 EEG 数据建立了枕顶 alpha 振荡的跨模态相位锁定。这些独立记录的变量，即枕部皮层兴奋性和反应性以及 EEG 相位动态，显着相关。这表明，振荡视觉皮层活动的跨模态相位锁定可以在人类大脑中产生，以周期性方式影响视觉处理的感知和 EEG 测量，与视觉区域中神经兴奋性的快速循环一致。
