The role of neural oscillations in coordinating competing cognitive processes

人类大脑如何灵活地采样和优先考虑传入的感官信息？想象一下新年前夜纽约市时代广场上的忙碌景象：高耸的摩天大楼，闪烁的灯光，刺耳的音乐，旋转的交通，五颜六色的人群，多种对话的喧闹声，所有这些都是在你试图听一个朋友用手机和你说话的时候。由于我们的大脑感官处理资源有限，我们根本无法完全处理所有涌入这个场景的感官信息。因此，我们选择性地将注意力集中在行为上最重要的信息和事件上。大脑使用注意力过滤器来确定什么应该优先考虑，这些过滤器可以提升相关信息。例如，注意力可以选择性地增强对朋友声音的听觉处理，并增强视觉处理，集中在你同意见面的街角。虽然以前的研究有时描述了特定位置的视觉注意力（例如，在一个特定的街角）作为一个持续的聚光灯，照亮行为上重要的信息，其他最近的调查表明，这种注意聚光灯闪烁约每秒四次。也就是说，注意力聚光灯的强度随着时间的推移有节奏地增加和减少。聚光灯的这种有节奏的闪烁表明，大脑每秒大约“签到”或“更新”四次，以确保注意聚光灯的当前焦点仍然是观察者最重要和最相关的焦点。这种有节奏的签到过程创造了时间窗口，当它更容易将注意力焦点转移到一个新的位置时，可能会在采样和转移行为之间创造一个关键的平衡。注意力聚光灯的节律性闪烁可能是作为一种生存机制而发展起来的，以帮助我们的祖先（和其他动物），例如，灵活地寻找食物，同时仍然注意捕食者。这个项目调查了正常人的神经起源和这种有节奏的注意力闪烁的行为后果。这项研究也可能揭示与异常有限的注意力灵活性相关的大脑疾病，如注意力缺陷多动障碍（ADHD），其中个体可以固定在与高度分心（即，移动行为）或超聚焦（即，为了研究视觉注意力聚光灯的强度如何以及为什么每秒有节奏地增加和减弱大约四次，这项研究使用了人类的眼睛跟踪（眼睛位置的行为测量）和脑电图（EEG，脑电活动的非侵入性全球测量）。首先，这项研究探讨了与较弱的注意力聚光灯相关的时间段是否也与注意力分散有关。这些实验的结果将检验一个假设，即大脑被连接成周期性的分心，以增强选择性注意力的更新。虽然这对于执行需要集中注意力和为意外事件做好准备的日常任务可能是至关重要的，例如在忙碌交通高峰时间驾驶汽车时可能遇到的情况，但在我们日益分散注意力的现代环境中可能存在问题（例如，笔记本电脑在我们面前打开，智能手机在附近）。第二，这个项目调查注意力聚光灯强度的节奏变化是否反映了大脑用来调解竞争功能的基本机制。先前的研究已经表明，在视觉处理中直接与注意力相关的提升的大脑区域（如大脑皮层中的额叶眼区）也会将眼球运动引向行为上重要的信息。该项目的实验测试这些大脑区域是否执行这些潜在的视觉和运动竞争（即，眼睛运动）通过随时间在它们之间交替而起作用，使得与较弱的视觉注意聚光灯相关联的时间段也与更多的眼睛运动相关联。最后，这个项目调查大脑是否使用这种竞争功能的节奏协调，不仅在感觉处理中，而且作为一种更普遍的机制来解决可能的认知冲突的来源，这可能发生在一个任务中，受试者被要求在短时间内同时记住几个类似的项目。这些实验测试这些要记住的项目的表征强度是否随时间有节奏地波动（即，类似于注意力视觉感官聚光灯的闪烁强度）。这项研究将增加对大脑如何从环境中动态地采样视觉信息以及大脑如何不断更新以保持关键认知灵活性的理解。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

How does the human brain flexibly sample and prioritize incoming sensory information? Imagine a busy scene in Times Square in New York City on New Year’s Eve: towering skyscrapers, flashing lights, blaring music, swirling traffic, a colorful crowd of mingling people, the hubbub of multiple conversations, all while you are trying to listen to a friend talking with you on your cell phone. Since our brain has limited sensory processing resources, we simply cannot fully process all of the surging flood of incoming sensory information arriving in this scene. So instead, we selectively focus our attention on the most behaviorally important information and events. The brain uses attentional filters to determine what should be prioritized, and these filters can boost relevant information. For example, attention can selectively boost auditory processing of your friend’s voice, and enhance visual processing, focused on the street corner where you agreed to meet. Whereas previous research has sometimes described visual attention at a specific location (e.g., at a specific street corner) as a sustained spotlight that illuminates behaviorally important information, other recent investigations have instead shown that this attentional spotlight flickers at about four times per second. That is, the strength of the attentional spotlight rhythmically increases and decreases over time. This rhythmic flickering of the spotlight suggests that the brain is “checking-in” or “updating” about four times per second to ensure that the present focus of the attentional spotlight is still the most important and relevant focus for the observer. This rhythmic checking-in process creates time windows when it is easier to shift the attentional spotlight to a new location, potentially creating a critical balance between sampling and shifting behaviors. Rhythmic flickering of the attentional spotlight may have developed as a survival mechanism to help our ancestors (and other animals), for example, flexibly look for food while still keeping an eye out for predators. This project investigates the neural origins and behavioral consequences of this rhythmic flickering of attention in normal human subjects. This research may also shed new light on brain disorders associated with abnormally limited attentional flexibility, such as attention deficit hyperactivity disorder (ADHD), in which individuals can become fixed in behavioral states associated with either high distractibility (i.e., shifting behaviors) or hyper-focus (i.e., sampling behaviors).In order to investigate how and why the strength of the visual attentional spotlight rhythmically waxes and wanes about four times per second, this research uses eye tracking (a behavioral measure of eye position), and electroencephalography (EEG, a non-invasive, global measure of electrical activity in the brain) in humans. First, this research explores whether time periods associated with a weaker attentional spotlight are also associated with increased distractibility. The results of these experiments will test the hypothesis that the brain is wired to be periodically distractible to enhance updating of selective attention. While this may be critical to performing everyday tasks that require both focus and preparedness for unexpected events, such as one may encounter while driving a car in busy rush-hour traffic, it is potentially problematic in our increasingly distracting modern environments (e.g., with a laptop open in front of us and a smart phone nearby). Second, this project investigates whether rhythmic change in the strength of the attentional spotlight reflects a fundamental mechanism that the brain uses to mediate competing functions. Previous research has shown that the very same brain regions (such as the frontal eye fields in the cerebral cortex) that direct attention-related boosts in visual processing, also direct eye movements toward behaviorally important information. This projects' experiments test whether these brain regions perform these potentially competing visual and motor (i.e., eye movements) functions by alternating between them over time, such that time periods associated with a weaker visual attentional spotlight are also associated with more eye movements. Finally, this project investigates whether the brain uses such rhythmic coordination of competing functions, not only in sensory processing, but as a more general mechanism for resolving sources of possible cognitive conflict, that might occur in a task where subjects are asked to simultaneously remember several similar items for a short period of time. These experiments test whether the strength of representations for these to-be-remembered items rhythmically fluctuates over time (i.e., similar to the flickering strength of the attentional visual sensory spotlight). This research will increase understanding both of how the brain dynamically samples visual information from the environment and also how the brain continuously updates to maintain critical cognitive flexibility.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.