Thalamic synchrony and the gating of information flow to cortex

描述（由申请人提供）：丘脑同步性在控制信息流到皮层中的作用感觉通路的普遍特性是它们不断适应感觉输入特性的变化。适应不仅仅是神经活动的疲劳或衰减，而是可以从根本上改变感觉通路敏感的特征，从而改变通路编码的内容。我们最近表明，通过在大鼠触须系统中持续的触觉刺激的适应引起了什么行为相关的功能皮层编码的根本变化：从检测触觉接触到触觉/胡须输入的不同速度之间的歧视。这种观察在多大程度上是普遍的，以及它是否在感知上表现出来，还没有得到很好的研究。在这个项目中，使用电生理学和相关的功能措施和行为的组合，我们将确定是否适应增强歧视的代价，通过调制丘脑输入到皮层的时间同步检测。我们这样做是通过一个综合的，平行的研究，使用多种记录技术在触须的麻醉大鼠的途径，并使用行为任务集中在检测和触觉刺激之间的歧视。具体来说，我们将测试是否适应切换的基本皮层处理模式从检测到歧视，通过调制的同步投射丘脑输入（AIM 1）。我们将直接测试的一般性，这个中心的假设在整个晶须偏转速度和方向，并在上下文中的空间敏锐度在晶须，并确定这种现象是如何形成的适应触觉输入的统计数据。第二，我们将直接测试适应是否在行为过程中将感知性能从检测器切换到检测器，以及丘脑同步性的调制是否介导了这种切换（AIM 2）。将训练大鼠检测胡须接触或区分附近胡须的接触，同时我们通过在触须特异性区域内和跨触须特异性区域长期植入多电极来监测VPm丘脑中的群体活动。重要性：长期以来，人们一直认为，适应的行为，以加强信息流的感觉通路和人类的心理物理学研究确实表明，在某些情况下，适应的行为，以提高辨别力的触觉输入。然而，丘脑皮层回路中潜在的神经表征与由此产生的神经感受之间的精确联系仍然是神经科学中的一个主要问题。我们目标的成功将直接决定皮层表征如何通过丘脑输入的调制而改变，以及这对感知的影响。广泛影响：各种大脑病理，如自闭症，脑震荡损伤和酗酒导致空间敏锐度的适应效果受损。我们目标的成功将为基于感觉的诊断提供更坚实的基础，并可能有助于阐明与这些改变生活的疾病相关的病理生理学。此外，我们探索的一种机制是丘脑同步性及其对皮质激活的影响，这与癫痫发作和丘脑疼痛有关。

DESCRIPTION (provided by applicant): The role of thalamic synchrony in gating information flow to cortex A ubiquitous property of sensory pathways is that they continuously adapt to changes in the properties of the sensory input. Adaptation is not simply fatigue or attenuation of neural activity, but instead can fundamentally change the features to which the sensory pathway are sensitive and thus changes what the pathway encodes. We have recently shown that adaptation through ongoing tactile stimulation in the rat vibrissa system induces a fundamental change in what behaviorally relevant features the cortex encodes: from detection of a tactile contact to discrimination between different speeds of the tactile/whisker input. To what extent this observation is general and whether it manifests perceptually has not been well studied. In this project, using a combination of electrophysiology and related functional measures and behavior, we will determine whether adaptation enhances discrimination at the expense of detection through modulation of the timing synchrony of thalamic input to cortex. We do so through an integrated, parallel study using multiple recording techniques in the vibrissa pathway of the anesthetized rat, and using behavioral tasks focused on detection of and discrimination between tactile stimuli. Specifically, we will test whether adaptation switches the fundamental cortical processing mode from detection to discrimination through modulation of synchrony of projecting thalamic input (AIM 1). We will directly test the generality of this central hypothesis across whisker deflection speed and direction, and in the context of spatial acuity across whiskers, and determine how this phenomenon is shaped by the statistics of the adapting tactile input. Second, we will directly test whether adaptation switches perceptual performance from detector to discriminator during behavior and whether modulation of thalamic synchrony mediates the switch (AIM 2). Rats will be trained to either detect whisker contact or discriminate between contacts of nearby whiskers, while we monitor population activity in VPm thalamus through chronically implanted multi-electrodes within and across vibrissa-specific regions. Significance: It has long been posited that adaptation acts to enhance information flow in sensory pathways and human psychophysical studies have indeed shown that in certain circumstances adaptation acts to enhance discriminability of tactile inputs. However, the precise link between the underlying neural representations in the thalamocortical circuit and the resultant percept remains a major open question in neuroscience. Success of our aims will directly determine how the cortical representation changes through modulation in thalamic input and the consequences of this on perception. Broad Impacts: Various brain pathologies such as autism, concussive injuries, and alcoholism result in an impaired effect of adaptation on spatial acuity. Success of our aims will provide a more solid foundation for sensory-based diagnostics, and may help to shed light on the pathophysiology associated with these life-altering disorders. Further, one mechanism that we explore is that of thalamic synchrony and its effect on cortical activation, which has been implicated in seizure generation and thalamic pain.