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

感知选择是我们大脑的一项基本功能。当面对复杂或模糊的视觉输入时，我们的大脑会自动地、不费脑力地选择并有意识地感知相关信息，并抑制无关信息。与此相反，将视觉注意力引导到特定的位置或特征是一个努力和主动的过程，可以通过增强被关注刺激的神经表征直接支持或与自动选择过程相互作用。在神经层面上，对于知觉选择的自发和自动性质之间的关系，注意在其中的作用，以及它们对通向意识的门控通路的贡献，人们知之甚少。在当前的应用中，我们的主要兴趣在于检查涉及双稳态选择的神经过程及其与定向注意机制的相互作用。我们的目的是阐明神经群体编码有意识感知和非感知刺激对感知选择结果的影响，并旨在测量它们各自通过定向注意的调节。为了实现这一目标，我们将检查额顶叶注意网络的不同节点及其与中级和早期视觉皮层的相互作用。心理物理学表明，双稳定观看涉及早期和高级加工之间的强烈相互作用，但对这种交流的神经基质知之甚少，以及它在自动感知选择和定向注意期间是否有所不同。它如何影响编码感知和非感知刺激表征的神经群也是未知的。这些问题可能会进一步揭示早期视觉皮层双稳定视觉实验中观察到的电生理信号和神经成像信号之间差异的潜在原因。我们建议由两位研究者进行五组实验，用适当的方法解决上述问题。特别是，我们将使用经颅磁刺激（TMS）在前额叶、顶叶和视觉专门化区域干扰大脑活动，以探测它们对知觉选择的直接影响。3特斯拉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 Tesla进行的超高分辨率功能磁共振成像研究旨在分析不同皮层层的活动，以检查在有意识访问或无意识访问、有或没有自上而下的注意时对神经群的前馈和反馈影响。研究结果将为感知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，并为意识和无意识加工的关系提供基本的线索。

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.