Understanding brain networks underlying perceptual selection and attention in bi-stable viewing.

知觉选择是我们大脑的一项基本功能。当面对复杂或模棱两可的视觉输入时，我们的大脑会选择并有意识地感知相关信息，并抑制不相关的信息，这是自动的，不需要精神上的努力。与此相反，将视觉注意力引导到特定位置或特征是一个费力和积极的过程，可以通过增强对所关注刺激的神经表征来直接支持自动选择过程或与其相互作用。在神经层面上，对于知觉选择的看似自发和自动的本质之间的关系，注意力在其中的作用，以及它们对通往意识的大门的贡献，人们知之甚少。在当前的应用中，我们的主要兴趣在于研究双稳态选择所涉及的神经过程及其与定向注意机制的相互作用。我们的目标是阐明编码有意识和无意识刺激的神经群体对知觉选择结果的影响，并旨在通过定向注意来衡量它们各自的调节。为了实现这一点，我们将研究额顶注意网络的不同节点以及它们与中层和早期视觉皮质的相互作用。心理物理学表明，双稳定观看涉及早期和较高水平的加工之间的强烈交互作用，但人们对这种交流背后的神经基础知之甚少，以及它在自动知觉选择和定向注意期间是否有所不同。它如何影响神经群体编码知觉和非知觉刺激表征也是未知的。这些问题可能会进一步揭示在早期视觉皮层的双稳态视觉实验中观察到的电生理信号和神经成像信号之间存在差异的潜在原因。我们提出了由两名研究人员进行的五组实验，使用适当的方法分别解决上述问题。特别是，我们将在有意识和无意识进入的前额叶、顶叶和视觉专门区使用经颅磁刺激(TMS)来干扰大脑活动，以探索它们对知觉选择的直接影响。在3特斯拉进行的功能磁共振实验将在全脑水平上补充这些研究。使用9.4特斯拉的超高分辨率功能磁共振研究旨在解析不同皮层的活动，以考察有无意识接触、有无自上而下注意的神经群体的前馈和反馈影响。结果将为知觉选择的神经机制及其与视觉注意的关系提供前所未有的见解，并为有意识和无意识加工的关系提供基础信息。

Perceptual selection is a fundamental function of our brain. When confronted with complex or ambiguous visual input, our brain selects and consciously perceives the relevant information and suppresses the irrelevant, automatically and without mental effort. In contrast to this, directing visual attention towards particular locations or features is an effortful and active process that can directly support or interact with automatic selection processes, by enhancing neural representations of the attended stimuli. At the neural level, only little is understood about the relationship between the seemingly spontaneous and automatic nature of perceptual selection, the role of attention in it, and their contribution to gating access to consciousness. In the current application, our main interest lies in examining neural processes involved in bistable selection and their interaction with mechanisms of directed attention. We aim to shed light on the influence of neural populations encoding consciously perceived versus unperceived stimuli on the outcome of perceptual selection, and aim to measure their respective modulation by directed attention. To achieve this, we will examine different nodes of the fronto-parietal attention network and their interaction with mid-level and early visual cortices. Psychophysics suggest that bi-stable viewing involves strong interactions between early and higher levels of processing, yet only little is known about the neural substrates underlying this communication, and whether it differs during automatic perceptual selection and during directed attention. It is also unknown how it affects neural populations encoding the perceived versus non-perceived stimulus representations. These questions may shed additional light onto potential reasons underlying the discrepancy between electrophysiological and neuroimaging signals observed in bi-stable vision experiments in early visual cortex.We propose five sets of experiments conducted by two researchers, addressing each of the above questions using the appropriate method. In particular, we will disturb brain activity using transcranial magnetic stimulation (TMS) in prefrontal, parietal and visually specialized areas with and without conscious access to probe their direct influence on perceptual selection. fMRI experiments at 3 Tesla will complement these studies at the whole-brain level. Ultra-high-resolution fMRI studies using 9.4 Tesla aim to resolve activity of different cortical layers to examine feedforward and feedback influences on neural populations with or without conscious access, with and without top-down attention.The results will provide unprecedented insights into neural mechanisms of perceptual selection and their relation to visual attention, and shed a fundamental light onto the relationship of both to conscious and unconscious processing.