Cortical and thalamic mechanisms of selective auditory attention

描述（由申请人提供）：大脑必须过滤大量涌入的感官信息，以选择与其当前目标相关的信息，以便适当地指导适应性行为。虽然对猕猴的研究已经确定了许多注意力对视觉处理的潜在影响机制，但很少有研究检查听觉系统中的相应影响。最近的研究结果提出了我们的总体假设，即注意力通过调节大脑中不同功能区域的局部兴奋性和信息的动态路由，以忽略刺激为代价增强了对被注意刺激的感官表征。拟议的研究的广泛目标是检查这一假设，从而定义这些相互关联的本地和网络为基础的过程的机制，以及它们的相对贡献，在听觉处理层次结构的不同节点的注意听觉刺激处理。根据我们的假设，注意调节正在进行的振荡活动，以匹配其属性（频率和相位）的全球声学特征出席刺激流（时间结构和音高分别），从而创建一个内部模型的形式，该流的阈下神经元振荡。这允许振荡充当基于模板的过滤器机制，其分离相关流并沿着听觉对象的沿着基本组织维度增强其处理。与此并行，振荡活动跨层次处理阶段的对齐通过提供与所关注的听觉流的时间结构相关联的用于通信的共同时间参考框架来偏置相关信息的传输。局部增强和基于网络的通信效果的关键是通过振荡相位重置将振荡相位对准相关事件的定时。越来越多的证据表明，相位重置是由直接的非丘系丘脑皮层传入，并通过丘脑网状核的自上而下的注意调制。我们的第一个具体目标是确定集合 这些规则定义了初级听觉皮层中的环境阈下活动受注意力和听觉刺激流的物理特性调节的方式。我们的第二个具体目标是定义的机制，并确定注意相关的功能连接的初级和高级带区域的听觉皮层之间的变化的作用。我们的第三个具体目标是确定丘脑结构，启动和调制振荡相位复位通过分析听觉丘脑和初级皮层区域的并发电生理活动，并使用电微刺激。在听觉丘脑皮层处理层次的不同节点上应用成对记录将提供关于动态大脑网络如何运作的基本信息，以及如何通过注意力进行调制。这将允许对听觉感知和注意力相关缺陷进行直接的机械解释，这些缺陷是许多衰弱性神经精神障碍的标志性症状。

DESCRIPTION (provided by applicant): The brain must filter the overwhelming influx of sensory information to select information that is relevant to its current goals, in order to appropriately guide adaptive behavior. While studies in macaque monkeys have identified many of the mechanisms underlying attention effects on visual processing, very few studies have examined corresponding effects in the auditory system. Recent findings raise our overarching hypothesis that attention enhances the sensory representation of attended stimuli at the expense of ignored ones both by modulating local excitability within, and the dynamic routing of information across distinct functional areas in the brain. The broad goal of the proposed research is to examine this hypothesis and thus define the mechanisms of these interrelated local and network based processes, as well as their relative contributions to attentive auditory stimulus processing in different nodes of the auditory processing hierarchy. According to our hypothesis, attention modulates ongoing oscillatory activity to match its properties (frequency and phase) to the global acoustic features of the attended stimulus stream (temporal structure and pitch respectively), thereby creating an internal model of that stream in the form of subthreshold neuronal oscillations. This allows the oscillations to act as a template-based filter mechanism that segregates the relevant stream and enhances its processing along fundamental organizing dimensions of auditory objects. Parallel to this, the alignment of oscillatory activity across hierarchical processing stages biases the transmission of relevant information by providing a common temporal reference frame for communication that is tied to the temporal structure of the attended auditory stream. A key to both local enhancement and network based communication effects is the alignment of oscillatory phase to the timing of relevant events by oscillatory phase reset. Converging evidence suggests that phase reset is initiated by direct non-lemniscal thalamocortical afferents, and is modulated by top-down attention via the reticular nucleus of the thalamus. Our first specific aim is to determine the set of rules that define the way ambient subthreshold activity in primary auditory cortex is modulated by attention and by the physical properties of auditory stimulus streams. Our second specific aim is to define the mechanism and determine the role of attention related changes in functional connectivity between primary and higher level belt regions of auditory cortex. Our third specific aim is to identify the thalamic structures that initiate and modulate oscillatory phse reset by analyzing the concurrent electrophysiological activity of auditory thalamic and primary cortical regions, and using electrical microstimulation. The application of paired recordings across different nodes of the auditory thalamocortical processing hierarchy will provide fundamental information on how dynamic brain networks function, and are modulated by attention. This will allow for a direct mechanistic interpretation of auditory perceptual and attention related deficits, which are hallmark symptoms of many debilitating neuropsychiatric disorders.