Systematic Evaluation of a Vibrissa Resonance Hypothesis

触须共振假说的系统评估

• 批准号: 6806043
• 负责人: Christopher I Moore
• 金额: $ 21.46万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6806043
• 关键词: albino rat; anesthesia; auditory cortex; behavior modification; biological models; biomechanics; electrical measurement; electrophysiology; electrostimulus; face; neural information processing; neuroanatomy; neurons; optical polarization; sensory signal detection; somesthetic sensory cortex; sound frequency; surface property; touch; vibrissae; video recording system

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.

描述(由申请人提供)：共振，结构在特定频率受到刺激时以更大幅度振荡的趋势，已被生物(例如耳蜗)和人造(例如功能磁共振)传感系统用来促进检测和识别。我们最近发现，当以特定频率受到刺激时，大鼠触须会产生共振，因此每个触觉都有一条频率的“调谐曲线”，放大了触觉运动的范围。此外，定义这些调谐曲线的基本共振频率随着触须长度的变化而变化：因为触须长度在老鼠脸上的位置不同，所以共振提供了频率敏感度的体视图。振动共振应该直接和显著地影响振动的神经表征，潜在地具有重要的知觉影响。在这里，我们建议系统地研究以下特定的假设：1.振动共振放大SI皮质神经元对小幅度高频触觉刺激的敏感性；2.振动共振使躯体相关的SI神经元获得带通频率调谐；3.大鼠面部的系统频率敏感性地图被转换为覆盖在躯体部位SI地图上的高频敏感性地图。为了用控制良好的刺激来验证这些假说，我们将在麻醉大鼠上进行电生理记录和光学成像(特定目标1和2)。为了在清醒的大鼠中测试这些假设，我们将在头部张贴的非扭动大鼠中使用相同的刺激和慢性四极管记录(特定目标3)。为了测试在搅拌过程中表达共振的假设，我们将训练头部张贴的大鼠在不同的质地上搅拌，并进行高速摄像(特定目标4)。这些研究之所以意义重大，有几个原因。触须的生物力学此前受到的关注相对较少。对触觉共振的神经关联的关键检查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SI中存在以前未发现的躯体定位高频映射，包括一个‘等频柱’网络。拟议的研究将在这个重要的模型系统中提供对感觉加工这一潜在关键方面的系统检查。