CAREER: Large-scale brain dynamics underlying visual perceptual awareness

尽管在过去的一个世纪里，神经科学取得了巨大的进步，但我们主观意识的神经生物学基础仍然是一个谜。过去几十年的进步使得这个问题的一个主要组成部分能够通过现代神经科学工具得到严格的解决。也就是说，大脑是如何产生对感官刺激的知觉的？特别是，神经科学家和心理学家一直在共同努力，解开视觉知觉的神经基础。目前，一个主要的悬而未决的问题是，人类额叶皮层的区域是否直接参与视觉知觉意识的内容，或者是否只参与维持和操纵后视皮层所代表的感知信息。在美国国家科学基金会职业奖的支持下，何碧宇博士将解决这个问题，并开发一个框架来理解视觉感知意识背后的大规模大脑动力学。为此，该项目结合了视觉心理物理学、最先进的多模态人脑成像、非侵入性脑刺激和计算建模。这项工作的结果将导致在规范和临床人群中更好地理解人类感知意识的生物学基础。该奖项支持的教育活动旨在激发学生对神经科学的科学兴趣和热情，并在人类神经科学研究中增加计算神经科学和最先进的多模态成像工具的使用。这项提议的研究目标是解决神经科学中的一个核心问题：大脑是如何产生对感官刺激的感知意识的？为了研究这个问题，研究小组将结合心理物理学、多模态脑成像和人类无创脑刺激，通过计算建模，并使用视觉作为模型系统。具体来说，本文解决了以下问题：1)当刺激模糊性必须解决时，额叶区域的神经活动是否有助于感知内容？额叶区域的神经活动是否有助于控制特定视觉信息对意识的获取？核心假设是，在有意识的视觉感知过程中，大规模的大脑活动表现出由额叶皮层和视觉皮层之间的相互作用形成的依赖于初始状态的、强大的、短暂的动态。实验方法的特点是使用超高场（7特斯拉）功能磁共振成像（fMRI）、脑磁图（MEG）和皮质电图（ECoG）的组合来记录全脑和大规模网络水平的大脑活动，以利用每种模式的高空间或高时间分辨率，并使用高清经颅直流电刺激（HD-tDCS）进一步操纵大脑活动。这些研究将对理解大脑系统如何协调产生对环境输入的感知意识产生重大影响。

Despite the enormous progress in neuroscience over the past century, the neurobiological basis of our subjective awareness remains a mystery. Advances over the past decades have now enabled one major component of this question to be rigorously addressed by modern neuroscientific tools. That is, how does the brain give rise to perceptual awareness of sensory stimuli? In particular, there has been a concerted effort by neuroscientists and psychologists to unravel the neural bases of visual perceptual awareness. Currently, one major open question is whether regions in the human frontal cortex directly contribute to the content of visual perceptual awareness or, alternatively, are only involved in the maintenance and manipulation of perceptual information represented in posterior visual cortices. With the support of this NSF CAREER award, Dr. Biyu He will address this question and develop a framework for understanding large-scale brain dynamics underlying visual perceptual awareness. To this end, the project combines visual psychophysics, state-of-the-art multimodal human brain imaging, noninvasive brain stimulation and computational modeling. The outcome of this work will lead to a better understanding of the biological basis of human perceptual awareness in both normative and clinical populations. The educational activities supported by this award are intended to stimulate scientific interest and enthusiasm in neuroscience in student populations, and increase the use of computational neuroscience and state-of-the-art multimodal imaging tools in human neuroscience research. The research objective of this proposal is to tackle a central question in neuroscience: How does the brain give rise to perceptual awareness of sensory stimuli? To investigate this question, the research group will combine psychophysics, multi-modal brain imaging, and noninvasive brain stimulation in humans, facilitated by computational modeling, and use vision as the model system. Specifically, the following questions are addressed: 1) Do neural activities in frontal regions contribute to perceptual content when stimulus ambiguity must be resolved? 2) Do neural activities in frontal regions contribute to gating the access to awareness by a particular piece of visual information? The central hypothesis is that large-scale brain activity during conscious visual perception exhibits initial-state-dependent, robust, transient dynamics shaped by the interactions between frontal and visual cortices. The experimental approach features recording of brain activity at whole-brain and large-scale network levels using a combination of ultra-high-field (7 Tesla) functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and electrocorticography (ECoG) to leverage the high spatial or high temporal resolution of each modality, and to further manipulate brain activity using high-definition transcranial direct current stimulation (HD-tDCS). These studies will have a major impact for understanding how brain systems coordinate to generate perceptual awareness of environmental input.