Neuronal oscillations as a tool for attentional stream selection

描述（由申请人提供）：在充斥我们感官的输入中注意和“选择”特定输入流的能力是一种关键的认知能力。我广泛的长期目标是确定大脑完成这种选择的神经元机制。许多生物产生的声学刺激（例如自然语音）的节奏结构与大脑中持续的节奏兴奋性波动（即，神经元振荡）提示了我的核心假设-这些振荡本身是可以用于形成被关注流的节奏结构的神经表征的工具，并且注意力对神经元振荡的强制夹带是感觉和知觉选择的关键机制。为了评估这些想法，我将记录来自手术癫痫患者听觉皮层及其周围植入电极的脑电图（EEG）信号，同时他们进行一系列听觉流选择任务。自然语音是有节奏的生物生成的声音流的原型示例，其在真实的生活情形中的处理通常需要选择性注意和忽略不相关背景噪声的能力，如在众所周知的“鸡尾酒会”情形中。因此，自然语言将是检验我的核心假设注意力强迫夹带的一个主要例子。然而，这种奋进是非常复杂的自上而下的语音，语义和情感的影响，也调用在语音处理。为了绕过这些问题，但直接在语音的基础上的节奏结构的注意力选择的问题，我将使用语义上无意义的声音流，组成，以便既剖析流选择的关键问题，并模仿语音节奏结构的关键方面。我的第一个具体目标是定义注意力强制夹带的最小节奏条件，以及它们对行为表现的影响。我将测试一个基本命题，即注意在两种不同的模式下运作，基于输入的时间结构：一个“节奏”模式，其中低频振荡夹带到关注流的时间结构被预测为注意选择的“工具”，和一个“随机”模式，其中输入流没有可检测的节奏;在这种情况下，我预测低频振荡将被抑制，因为它们将成为刺激辨别的一种倾向。我的第二个具体目标是研究选择性夹带流与层次节奏结构模仿语音的关键组成部分。研究神经元振荡作为选择性注意的工具可能会提高我们对广泛的神经精神疾病（包括ADHD和精神分裂症）中注意功能障碍的理解，据报道，受影响的个体将神经元振荡带入节律刺激的能力降低。更直接，也许更重要的是，研究结果也可能有助于理解有时在癫痫患者中观察到的注意力缺陷，这是参与拟议研究的人群。 公共卫生相关性：在这项研究中，我将研究选择性地注意到一个重要的声音刺激，发生在其他无关的声音流，从而模拟一个重要的现实生活中的情况，这是一个重大的挑战，人类在日常生活中经常面临的大脑机制。我将测试特定的假设，关于自然声流的注意力选择的节律性的效用，这可能对理解一些干扰注意力的神经缺陷有影响，并有助于像多动症和精神分裂症，以及理解癫痫患者可能发生的注意力缺陷。

DESCRIPTION (provided by applicant): The ability to attend to and "select" a particular stream of input amidst those flooding our senses is a critical cognitive capacity. My broad, LONG TERM OBJECTIVE is to define the neuronal mechanisms by which the brain accomplishes this selection. The striking similarity between the rhythmic structure of many biologically- generated acoustic stimuli, such as natural speech, and of that ongoing rhythmic excitability fluctuations in the brain (i.e., neuronal oscillations) prompts my core hypothesis - that these oscillations themselves are tools that can be used to form a neural representation of the rhythmic structure of an attended stream, and that attention- enforced entrainment of neuronal oscillations is a key mechanism for sensory and perceptual selection. To evaluate these ideas, I will record electroencephalographic (EEG) signals from implanted electrodes in and surrounding auditory cortex in surgical epilepsy patients, while they engage in a series of auditory stream selection tasks. Natural speech is a prototypic example of a rhythmic biologically-generated acoustical stream, whose processing in real life situations often demands selective attention and the ability to ignore irrelevant background noises, as in the well known "cocktail party" situation. Thus natural speech would be a prime example for testing my core hypothesis of attention-enforced entrainment. However this endeavor is enormously complicated by top-down phonologic, semantic and emotional influences that are also invoked during speech processing. To bypass these problems and yet get directly at the issue of attentional selection based on speech's underlying rhythmic structure, I will the use semantically meaningless sound streams, composed so as to both dissect key issues in stream selection, and mimic key aspects of rhythmic structure in speech. My FIRST SPECIFIC AIM is to define minimal rhythmic conditions for attention-enforced entrainment, and their impact on behavioral performance. I will test a fundamental proposition that attention operates in two distinct modes based on the temporal structure of the input: a "rhythmic" mode, in which low frequency oscillatory entrainment to the temporal structure of the attended stream is predicted to operate as an "instrument" of attentional selection, and a "random" mode, in which the input stream has no detectable rhythm; in this case, I predict that low frequency oscillations will be suppressed, as they would then be a liability to stimulus discrimination. My SECOND SPECIFIC AIM is to examine selective entrainment to streams with hierarchical rhythmic structures mimicking key components of speech. Investigating neuronal oscillations as instruments of selective attention may improve our understanding of attentional dysfunction in a broad spectrum of neuropsychiatric disorders including ADHD and schizophrenia, in which affected individuals reportedly have reduced capacity to entrain neuronal oscillations to rhythmic stimuli. More directly, and perhaps more importantly, findings may also be helpful in understanding attentional deficits that are sometimes observed in epilepsy patients, which is the population participating in the proposed study. PUBLIC HEALTH RELEVANCE: In this study I will study the brain mechanism involved in selectively attending to an important acoustic stimulus that occurs among other irrelevant acoustic stream, thus simulating an important real-life of situation, which is a major challenge humans are faced with regularly in daily life. I will test specific hypotheses regarding the utility of rhythmicity for attentional selection of naturalistic acoustic streams, which may have implications for understanding some of the neural defects that interfere with attention, and contribute to disorders like ADHD and schizophrenia, as well as in understanding attentional deficits that can occur in epilepsy patients.