Systematic Evaluation of a Vibrissa Resonance Hypothesis

描述（由申请人提供）：共振，即结构在特定频率下受到刺激时以较大幅度振荡的趋势，已被生物（如耳蜗）和人工（如fMRI）传感系统用于促进检测和识别。我们最近发现，老鼠的触须在特定频率下受到刺激时会产生共鸣，这样每个触须都有一个频率的“调谐曲线”，可以放大触须运动的范围。此外，定义这些调谐曲线的基本共振频率随触须长度的变化而变化：因为触须长度随大鼠面部位置的变化而变化，共振提供了频率敏感性的体位图。触须共振应该直接和显著地影响触须的神经表征，具有潜在的重要知觉意义。在此，我们建议对以下具体假设进行系统研究：触须共振增强了SI皮质神经元对小振幅高频触觉刺激的敏感性；2. 振动共振赋予体位相关的SI神经元带通频率调谐；, 3。大鼠面部频率敏感性的系统图被转换成覆盖在躯体SI图上的高频敏感性图。为了在控制良好的刺激下验证这些假设，我们将对麻醉大鼠进行电生理记录和光学成像（Specific Aims 1和2）。为了在清醒的大鼠中验证这些假设，我们将在头贴、不拍打的大鼠中使用相同的刺激和慢性四电极记录（Specific Aim 3）。为了验证共振在搅拌过程中表达的假设，我们将训练头贴大鼠在不同的纹理上搅拌，并进行高速摄像（具体目标4）。这些研究之所以重要，有几个原因。以前，有关触须的生物力学研究很少受到重视。对触须共振的神经关联的批判性研究可能为触觉信号转导的新理论提供证据。此外，初步数据强烈表明，大鼠SI神经元是带通频率调谐的，并且在SI中存在一个以前未被发现的体位高频图，包括一个“同频”列网络。提出的研究将提供系统的检查这个潜在的关键方面的感觉处理在这个重要的模型系统。

DESCRIPTION (provided by applicant): Resonance, the tendency of structures to oscillate at larger amplitudes when stimulated at specific frequencies, has been employed by biological (e.g., the cochlea) and artificial (e.g., fMRI) sensing systems to facilitate detection and discrimination. We have recently discovered that rat-vibrissae resonate when stimulated at specific frequencies, such that each vibrissa has a 'tuning curve' of frequencies that amplify the range of vibrissa motion. Further, the fundamental resonance frequency that defines these tuning curves varies as a function of vibrissa length: Because vibrissa lengths vary by position on the rat face, resonance provides a somatotopic map of frequency sensitivity. Vibrissa resonance should directly and significantly impact the neural representation of the vibrissae, with potentially important perceptual implications. Here, we propose to systematically investigate the following specific hypotheses: 1. That vibrissa resonance amplifies the sensitivity of SI cortical neurons to small-amplitude high-frequency tactile stimuli; 2. That vibrissa resonance confers band-pass frequency tuning to somatotopically associated SI neurons; and, 3. That the systematic map of frequency sensitivity on the rat face is translated into a map of high-frequency sensitivity overlaid on the somatotopic SI map. To test these hypotheses with well-controlled stimuli, we will conduct electrophysiological recording and optical imaging in the anesthetized rat (Specific Aims 1 & 2). To test these hypotheses in the awake rat, we will employ identical stimuli and chronic tetrode recording in the head-posted, non-whisking rat (Specific Aim 3). To test the hypothesis that resonance is expressed during whisking, we will train head-posted rats to whisk over varying textures and conduct high-speed videography (Specific Aim 4). These studies are significant for several reasons. The biomechanics of the vibrissae have previously received relatively little attention. Critical examination of the neural correlates of vibrissa resonance may provide evidence for a new theory of tactile signal transduction. Further, Preliminary Data strongly suggest that rat SI neurons are band-pass frequency-tuned, and that a previously undiscovered, somatotopic high frequency map exists in SI, including a network of 'isofrequency' columns. The proposed studies will provide systematic examination of this potentially key aspect of sensory processing in this important model system.