Neuronal oscillations as a tool for attentional stream selection

描述(由申请者提供)：在充斥着我们感官的信息中注意并“选择”特定输入流的能力是一种关键的认知能力。我的长期目标是确定大脑完成这一选择的神经机制。许多生物产生的声音刺激(如自然语言)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)之间的惊人相似性促使我提出了核心假设--这些振荡本身是可以用来形成被关注的流的节奏结构的神经表示的工具，而神经振荡的注意力强制夹带是感官和知觉选择的关键机制。为了评估这些想法，我将记录外科癫痫患者在进行一系列听觉流选择任务时，在听觉皮质内和周围植入电极的脑电(EEG)信号。自然语音是有节奏的生物产生的声学流的典型例子，在现实生活中，其处理通常需要选择性的注意和忽略无关背景噪音的能力，就像众所周知的“鸡尾酒会”情况一样。因此，自然语言将是检验我的注意力强制夹带的核心假说的最好例子。然而，这一努力由于自上而下的语音、语义和情感影响而变得非常复杂，这些影响也在语音处理过程中被调用。为了绕过这些问题，并直接涉及基于语音潜在节奏结构的注意力选择问题，我将使用无语义意义的声音流，其组成既是为了剖析流选择中的关键问题，也是为了模仿语音中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，即基于输入的时间结构，注意力以两种不同的模式运作：一种是“节奏”模式，在这种模式中，对被关注流的时间结构的低频振荡夹带被预测为注意力选择的“工具”；另一种是“随机”模式，在这种模式下，输入流没有可检测到的节奏；在这种情况下，我预测低频振荡将被抑制，因为它们将容易受到刺激的辨别。我的第二个具体目标是检查对具有模仿语音关键成分的分层节奏结构的流的选择性夹带。研究神经元振荡作为选择性注意的工具，可能会提高我们对包括ADHD和精神分裂症在内的广泛神经精神疾病中注意功能障碍的理解，在这些疾病中，据报道，受影响的个体将神经元振荡带入节奏刺激的能力降低。更直接，也许更重要的是，这些发现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。

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.