Corticofugal control of brainstem sensory gating in the rodent whisker system

啮齿类动物胡须系统中脑干感觉门控的皮质控制

• 批准号: 225988852
• 负责人: Dr. Shubhodeep Chakrabarti, Ph.D.
• 金额: --
• 依托单位: Werner Reichardt-Centrum für integrative Neurowissenschaften (CIN)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/225988852?language=en
• 关键词: Corticofugal; control; brainstem; sensory; gating

Rodents exhibit a wide repertoire of behaviors whilst exploring their immediate environment through the use of their large vibrissae or whiskers. In a specific behavior, known as active touch, they explore objects with their whiskers and manipulate the position of these tactile sensors to extract maximal information about the object. During such contacts, sensory processing is altered as compared to periods of quiescence. Specifically, the sensory responses in the tactile responsive neurons of the trigeminal complex are reduced. By contrast, passive contacts with an object in the absence of whisker movements evoke large responses in these neurons. Such sensory gating apparently maximizes detection of unexpected objects in the vicinity. Recent studies suggest that gating through brainstem trigeminal nuclei is mediated by corticofugal inputs which differentially modulate trigeminal circuitry. Neurons in specific compartments of primary somatosensory cortex (S1 septa) increase sensory transmission through the trigeminal brainstem whereas secondary somatosensory cortex (S2) inhibits it. However, several key factors in such a scheme remain to be elucidated. First, the projections from septa to the trigeminal complex have never been anatomically determined. Second, the responses of the various trigeminal nuclei in an awake behaving animal during active touch/quiescence have not been characterized. Third, the effect of modulatory influence of cortical projections on trigeminal nuclei on perception has never been tested. In this proposal we aim to clarify these points via a combined approach utilizing anatomical tract tracing, neurophysiological recordings, optogenetics and behavioral methods. First, we will determine and quantify the projections from S1 septa to the trigeminal nuclei. Second, we will record from these trigeminal nuclei and cortex in the same awake animal and characterize trigeminal responses in the different behavioral states. Cross correlation analysis will be applied to study their dependence on cortical drive. Finally, we will optogenetically manipulate S1 and S2 recipient structures in the trigeminal nuclei and quantify ensuing changes in perception. This will be the first attempt to characterize top down, cortical influences on whisker-related tactile gating in the brainstem in an awake animal and has important implications in the study of cortical effects on perception.

啮齿动物表现出广泛的行为，同时探索他们的直接环境，通过使用他们的大触须或胡须。在一种被称为主动触摸的特定行为中，它们用胡须探索物体，并操纵这些触觉传感器的位置，以提取有关物体的最大信息。在这种接触期间，感觉处理与静止期相比发生了变化。具体地，三叉神经复合体的触觉反应神经元中的感觉反应减少。相比之下，在没有胡须运动的情况下与物体的被动接触会在这些神经元中引起大的反应。这种感觉门控显然最大限度地检测附近的意外物体。最近的研究表明，通过脑干三叉神经核门控介导的离皮质输入的差异调制三叉神经回路。初级躯体感觉皮层（S1隔）的特定区域的神经元增加通过三叉神经脑干的感觉传递，而次级躯体感觉皮层（S2）抑制它。首先，从隔到三叉神经复合体的投射从未在解剖学上确定过。第二，各种三叉神经核在清醒的行为动物在主动触摸/静止的反应还没有被表征。第三，皮层投射对三叉神经核的调节作用对知觉的影响从未被测试过。在这项提案中，我们的目标是澄清这些点，通过一个综合的方法，利用解剖道跟踪，神经生理学记录，光遗传学和行为的方法。首先，我们将确定和量化从S1隔到三叉神经核的投射。其次，我们将记录这些三叉神经核和皮层在同一清醒的动物和不同的行为状态下的三叉神经反应的特点。交叉相关分析将用于研究它们对皮层驱动的依赖性。最后，我们将光遗传学操纵三叉神经核中的S1和S2受体结构，并量化随后的感知变化。这将是第一次尝试表征自上而下，皮层影响的胡须相关的触觉门控在清醒的动物脑干中，并在研究皮层对感知的影响具有重要意义。