Neuronal mechanisms of attentional selection in primary auditory cortex

描述（由申请人提供）：选择性注意通过以不相关刺激为代价增强任务相关刺激的神经表征来使感觉处理适应观察者的直接目标。先前对人类和猴子的研究表明，注意力调节视网膜后视觉处理的每个阶段的神经元反应。虽然听觉选择性注意已经在人类身上得到了广泛的研究，但在猴子身上的研究几乎没有涉及这个话题。这个R21建议的广泛目标是通过在猴子的初级听觉皮层（A1）中直接电生理记录来启动选择性注意的神经机制的研究。 越来越多的证据表明，神经元振荡反映了不同的空间和时间尺度上的神经元集合的兴奋性有组织的节奏变化，这些振荡是正常的大脑功能的基本组成部分，在感觉，认知和运动操作中起着至关重要的作用。特别是，最近在视觉皮层的研究表明，正在进行的振荡活动的结构可以适应或“夹带”的时间（节奏）结构的出席感官刺激流。卷吸使神经元振荡的高兴奋性阶段与被关注流中事件的时间相一致，从而放大它们的神经元表征。由于节奏结构对于许多生物学上重要的声学刺激（例如，语音），振荡夹带似乎特别有用的听觉系统中的注意力选择的机制。这个命题有很强的心理物理支持，但尚未在神经生理学水平上进行直接测试。我们将评估的总体假设，即夹带的神经元振荡的时间结构的关注声流的结果在增强的神经元反应的事件，包括该流，和抑制神经元反应的刺激，偏离它沿着两个基本的组织维度的听觉处理，时间（节奏）和频率。行为测量，沿着层流电流源密度和任务执行期间在A1中采样的多单元活动概况，将解决定义1）注意节奏和2）注意音调频率对听觉处理的影响的特定目标。 由于神经元振荡的注意夹带对于复杂环境中的有效适应行为至关重要，因此其中断可能会导致认知障碍。定义注意诱导的神经基础是理解认知功能和功能障碍机制的关键一步。 公共卫生相关性：神经元振荡的注意夹带被认为是至关重要的，以有效地利用正在进行的生理过程中的适应性处理复杂的自然刺激，但规则，管理它和它的功能仍然在很大程度上是未知的。我们建议探讨振荡夹带作为听觉选择性注意的机制。由于听觉处理缺陷是许多神经精神疾病的关键症状，我们的研究结果将对改善这些疾病的理解和治疗，以及促进我们对动态脑操作的理解具有重要意义。

DESCRIPTION (provided by applicant): Selective attention adapts sensory processing to the immediate goals of an observer by enhancing the neural representation of task relevant stimuli at the expense of irrelevant stimuli. Prior studies in both humans and monkeys show that attention modulates neuronal responses at every stage of visual processing after the retina. While auditory selective attention has been extensively studied in humans the topic is almost untouched by studies in monkeys. The broad goal of this R21 proposal is to initiate studies of the neural mechanisms of selective attention by direct electrophysiological recording in primary auditory cortex (A1) of the monkey. Accumulating evidence indicates that neuronal oscillations reflect organized rhythmic shifting of excitability in neuronal ensembles on different spatial and temporal scales, and that these oscillations are fundamental components of normal brain function with a crucial role in sensory, cognitive and motor operations. In particular, recent studies in visual cortex reveal that the structure of ongoing oscillatory activity can adapt or "entrain" to the temporal (rhythmic) structure of an attended sensory stimulus stream. Entrainment aligns the high excitability phase of neuronal oscillations with the timing of events in the attended stream, thus amplifying their neuronal representation. As rhythmic structure is essential to many biologically significant acoustic stimuli (e.g., speech sounds), oscillatory entrainment would appear particularly useful as a mechanism of attentional selection in the auditory system. This proposition has strong psychophysical support, but has not been directly tested at a neurophysiological level. We will evaluate the overall hypothesis that the entrainment of neuronal oscillations to the temporal structure of an attended acoustic stream results in enhanced neuronal responses to events that comprise that stream, and suppressed neuronal responses to stimuli that deviate from it along the two fundamental organizing dimensions of auditory processing, time (rhythm) and frequency. Behavioral measures, along with laminar current source density and multiunit activity profiles sampled in A1 during task performance will address the specific aims of defining the effects of 1) attended rhythm, and 2) attended tone frequency on auditory processing. Since attentional entrainment of neuronal oscillations appears critical to efficient, adaptive behavior in a complex environment, its disruption would likely result in cognitive impairment. Defining the neural underpinnings of attention entrainment is a crucial step in understanding the mechanisms of cognitive function and dysfunction. PUBLIC HEALTH RELEVANCE: Attention entrainment of neuronal oscillations is believed to be crucial to the effective use of ongoing physiological processes in adaptive processing of complex natural stimuli, yet the rules that govern it and its function are still largely unknown. We propose to explore oscillatory entrainment as a mechanism of auditory selective attention. Since deficits of auditory processing are key symptoms in numerous neuropsychiatric disorders, our findings will have important implications for improved understanding and treatment of these disorders, and for advancing our understanding of dynamic brain operations in general.