Thalamic synchrony and the gating of information flow to cortex

描述(申请人提供)：丘脑同步性在控制信息流向皮质中的作用感觉通路的一个普遍特征是它们不断地适应感觉输入特性的变化。适应并不是简单的神经活动的疲劳或减弱，而是可以从根本上改变感觉通路对其敏感的特征，从而改变通路的编码。我们最近证明，通过持续的触觉刺激在大鼠触觉系统中进行适应，会导致大脑皮层编码的行为相关特征发生根本变化：从检测触觉接触到区分不同速度的触觉/胡须输入。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，我们将结合电生理学和相关的功能测量和行为，确定适应是否通过调节丘脑输入大脑皮质的时序同步性来提高辨别力，并以牺牲检测为代价。我们通过一项综合的平行研究，使用麻醉大鼠触觉通路中的多种记录技术，并使用专注于检测和区分触觉刺激的行为任务来做到这一点。具体地说，我们将测试适应性是否通过调节丘脑投射输入的同步性将基本皮层处理模式从检测切换到辨别(AIM 1)。我们将直接测试这一中心假设在胡须偏转速度和方向上的普遍性，以及在胡须上的空间敏锐度的背景下，并确定这一现象是如何通过适应触觉输入的统计来塑造的。其次，我们将直接测试适应是否在行为过程中将知觉表现从检测器切换到鉴别器，以及丘脑同步性的调制是否调节了这种切换(目标2)。我们将训练大鼠探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定区域内和跨触须特定区域长期植入多个电极来监测VPM丘脑的种群活动。意义：长期以来，人们一直认为，适应的作用是增强感觉通路中的信息流，人类心理物理研究确实表明，在某些情况下，适应的作用是增强触觉输入的辨别能力。然而，丘脑皮质环路中潜在的神经表征和由此产生的知觉之间的确切联系仍然是神经科学中的一个主要悬而未决的问题。我们的目标的成功将直接决定大脑皮质表征如何通过丘脑输入的调制而变化，以及这对知觉的影响。广泛的影响：自闭症、脑震荡损伤和酒精中毒等各种脑部疾病导致适应对空间敏锐度的影响受损。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，我们探索的一个机制是丘脑的同步性及其对皮质激活的影响，这与癫痫的产生和丘脑疼痛有关。 与公共健康相关：感官输入在我们的日常生活中至关重要，无论是对我们周围世界的感知，还是对帮助我们与外部世界互动的肌肉系统的反馈。神经系统是如何完成这一壮举的，以及这到底是如何在我们的环境中帮助我们的，目前尚不清楚。在这一领域的发现可能有助于我们了解一些神经系统疾病/疾病，这些疾病的个体表现出敏感度/敏感度的丧失，并且没有能力适应感觉环境的变化。

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. PUBLIC HEALTH RELEVANCE: Sensory input is critical in our daily lives, for both the perception of the world around us, and in providing feedback for our muscle systems that help us interact with the external world. How the nervous system performs this feat, and precisely how this helps us in our environment, is unknown. Discovery in this area can potentially help us understand a number of disorders/diseases of the nervous system for which individuals exhibit loss of acuity/sensitivity, and do not have the ability to adapt to changes in the sensory environment.