Department of Physiology and Pharmacology, Sackler School of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
Sagol Brain Institute, Wohl Institute for Advanced Imaging, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel; Sackler School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel; Department of Anesthesiology, Critical Care and Pain Medicine, Tel Aviv Sourasky Medical Center, Tel Aviv 6423906, Israel.
Curr Biol. 2018 Jul 23;28(14):2239-2249.e6. doi: 10.1016/j.cub.2018.05.051. Epub 2018 Jul 5.
An identical sensory stimulus may or may not be incorporated into perceptual experience, depending on the behavioral and cognitive state of the organism. What determines whether a sensory stimulus will be perceived? While different behavioral and cognitive states may share a similar profile of electrophysiology, metabolism, and early sensory responses, neuromodulation is often different and therefore may constitute a key mechanism enabling perceptual awareness. Specifically, noradrenaline improves sensory responses, correlates with orienting toward behaviorally relevant stimuli, and is markedly reduced during sleep, while experience is largely "disconnected" from external events. Despite correlative evidence hinting at a relationship between noradrenaline and perception, causal evidence remains absent. Here, we pharmacologically down- and upregulated noradrenaline signaling in healthy volunteers using clonidine and reboxetine in double-blind placebo-controlled experiments, testing the effects on perceptual abilities and visually evoked electroencephalography (EEG) and fMRI responses. We found that detection sensitivity, discrimination accuracy, and subjective visibility change in accordance with noradrenaline (NE) levels, whereas decision bias (criterion) is not affected. Similarly, noradrenaline increases the consistency of EEG visually evoked potentials, while lower noradrenaline levels delay response components around 200 ms. Furthermore, blood-oxygen-level-dependent (BOLD) fMRI activations in high-order visual cortex selectively vary along with noradrenaline signaling. Taken together, these results point to noradrenaline as a key factor causally linking visual awareness to external world events. VIDEO ABSTRACT.
相同的感觉刺激可能会也可能不会被纳入感知体验，这取决于生物体的行为和认知状态。那么，是什么决定了一个感觉刺激是否会被感知到呢？虽然不同的行为和认知状态可能具有相似的电生理学、代谢和早期感觉反应特征，但神经调制通常不同，因此可能构成使感知意识成为可能的关键机制。具体来说，去甲肾上腺素能改善感觉反应，与朝向行为相关刺激的定向相关，并且在睡眠期间明显减少，而经验在很大程度上与外部事件“断开”。尽管相关证据暗示去甲肾上腺素与感知之间存在关系，但因果证据仍然缺乏。在这里，我们使用可乐定和瑞波西汀在双盲安慰剂对照实验中在健康志愿者中下调和上调去甲肾上腺素信号，测试其对感知能力以及视觉诱发脑电图（EEG）和 fMRI 反应的影响。我们发现，检测灵敏度、区分准确性和主观可见性随去甲肾上腺素（NE）水平变化而变化，而决策偏差（标准）不受影响。同样，去甲肾上腺素增加了 EEG 视觉诱发电位的一致性，而较低的去甲肾上腺素水平会使反应成分延迟约 200 毫秒。此外，高级视觉皮层中的血氧水平依赖（BOLD）fMRI 激活选择性地随去甲肾上腺素信号而变化。总之，这些结果表明去甲肾上腺素是将视觉意识与外部世界事件联系起来的关键因素。视频摘要。
