Vidal Juan R, Perrone-Bertolotti Marcela, Kahane Philippe, Lachaux Jean-Philippe
INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Brain Dynamics and Cognition Team, Lyon - Université Claude Bernard Lyon 1, Lyon, France ; University Grenoble Alpes, LPNC, F -38040 Grenoble France ; CNRS, LPNC, UMR 5105, F -38040 Grenoble France.
University Grenoble Alpes, LPNC, F -38040 Grenoble France ; CNRS, LPNC, UMR 5105, F -38040 Grenoble France.
Front Psychol. 2015 Jan 15;5:1545. doi: 10.3389/fpsyg.2014.01545. eCollection 2014.
If conscious perception requires global information integration across active distant brain networks, how does the loss of conscious perception affect neural processing in these distant networks? Pioneering studies on perceptual suppression (PS) described specific local neural network responses in primary visual cortex, thalamus and lateral prefrontal cortex of the macaque brain. Yet the neural effects of PS have rarely been studied with intracerebral recordings outside these cortices and simultaneously across distant brain areas. Here, we combined (1) a novel experimental paradigm in which we produced a similar perceptual disappearance and also re-appearance by using visual adaptation with transient contrast changes, with (2) electrophysiological observations from human intracranial electrodes sampling wide brain areas. We focused on broadband high-frequency (50-150 Hz, i.e., gamma) and low-frequency (8-24 Hz) neural activity amplitude modulations related to target visibility and invisibility. We report that low-frequency amplitude modulations reflected stimulus visibility in a larger ensemble of recording sites as compared to broadband gamma responses, across distinct brain regions including occipital, temporal and frontal cortices. Moreover, the dynamics of the broadband gamma response distinguished stimulus visibility from stimulus invisibility earlier in anterior insula and inferior frontal gyrus than in temporal regions, suggesting a possible role of fronto-insular cortices in top-down processing for conscious perception. Finally, we report that in primary visual cortex only low-frequency amplitude modulations correlated directly with perceptual status. Interestingly, in this sensory area broadband gamma was not modulated during PS but became positively modulated after 300 ms when stimuli were rendered visible again, suggesting that local networks could be ignited by top-down influences during conscious perception.
如果有意识的感知需要跨活跃的远距离脑网络进行全局信息整合，那么意识感知的丧失如何影响这些远距离网络中的神经处理呢？关于知觉抑制（PS）的开创性研究描述了猕猴大脑初级视觉皮层、丘脑和外侧前额叶皮层中特定的局部神经网络反应。然而，PS的神经效应很少在这些皮层之外以及同时跨远距离脑区进行脑内记录研究。在这里，我们将（1）一种新颖的实验范式与（2）来自采样广泛脑区的人类颅内电极的电生理观察相结合，在该实验范式中，我们通过使用具有瞬态对比度变化的视觉适应来产生类似的知觉消失和再次出现。我们关注与目标可见性和不可见性相关的宽带高频（50 - 150赫兹，即伽马）和低频（8 - 24赫兹）神经活动幅度调制。我们报告称，与宽带伽马反应相比，低频幅度调制在包括枕叶、颞叶和额叶皮层在内的不同脑区的更大一组记录位点中反映了刺激的可见性。此外，宽带伽马反应的动力学在岛叶前部和额下回比在颞叶区域更早地区分了刺激的可见性与不可见性，这表明额岛叶皮层在有意识感知的自上而下处理中可能发挥作用。最后，我们报告称，在初级视觉皮层中，只有低频幅度调制与知觉状态直接相关。有趣的是，在这个感觉区域，宽带伽马在PS期间没有被调制，但在300毫秒后当刺激再次变得可见时变为正向调制，这表明在有意识感知期间，局部网络可能受到自上而下的影响而被激活。
