Yuasa Kenichi, Groen Iris I A, Piantoni Giovanni, Montenegro Stephanie, Flinker Adeen, Devore Sasha, Devinsky Orrin, Doyle Werner, Dugan Patricia, Friedman Daniel, Ramsey Nick F, Petridou Natalia, Winawer Jonathan
Department of Psychology, New York University, New York, United States.
Division of Neural Dynamics, Department of System Neuroscience, National Institute for Physiological Sciences, Okazaki, Japan.
Elife. 2025 Jun 13;12:RP90387. doi: 10.7554/eLife.90387.
Neuronal oscillations at about 10 Hz, called alpha oscillations, are often thought to arise from synchronous activity across the occipital cortex and are usually largest when the cortex is inactive. However, recent studies measuring visual receptive fields have reported that local alpha power increases when cortex is excited by visual stimulation. This contrasts with the expectation that alpha oscillations are associated with cortical inactivity. Here, we used intracranial electrodes in human patients to measure alpha oscillations in response to visual stimuli whose location varied systematically across the visual field. We hypothesized that stimulus-driven local increases in alpha power result from a mixture of two effects: a reduction in alpha oscillatory power and a simultaneous increase in broadband power. To test this, we implemented a model to separate these components. The two components were then independently fit by population receptive field (pRF) models. We find that the alpha pRFs have similar center locations to pRFs estimated from broadband power but are several times larger and exhibit the opposite effect: alpha oscillatory power decreases in response to stimuli within the receptive field, reinforcing the link between alpha oscillations and cortical inactivity, whereas broadband power increases. The results demonstrate that alpha suppression in the human visual cortex can be precisely tuned, but that to measure these effects, it is essential to separate the oscillatory signal from broadband power changes. Finally, we show how the large size and the negative valence of alpha pRFs can explain key features of exogenous visual attention.
频率约为10赫兹的神经元振荡，即所谓的阿尔法振荡，通常被认为源于枕叶皮质的同步活动，并且通常在皮质不活跃时最为强烈。然而，最近测量视觉感受野的研究报告称，当皮质受到视觉刺激而兴奋时，局部阿尔法功率会增加。这与阿尔法振荡与皮质不活动相关的预期形成了对比。在这里，我们使用人类患者的颅内电极来测量对视觉刺激的阿尔法振荡，这些视觉刺激的位置在视野中系统地变化。我们假设，刺激驱动的局部阿尔法功率增加是由两种效应的混合导致的：阿尔法振荡功率的降低和宽带功率的同时增加。为了验证这一点，我们实施了一个模型来分离这些成分。然后，通过群体感受野（pRF）模型对这两个成分进行独立拟合。我们发现，阿尔法pRF的中心位置与从宽带功率估计的pRF相似，但尺寸大几倍，并且表现出相反的效应：阿尔法振荡功率在感受野内对刺激作出反应时降低，加强了阿尔法振荡与皮质不活动之间的联系，而宽带功率增加。结果表明，人类视觉皮质中的阿尔法抑制可以被精确调节，但为了测量这些效应，将振荡信号与宽带功率变化分离至关重要。最后，我们展示了阿尔法pRF的大尺寸和负价如何能够解释外源性视觉注意的关键特征。
