Optical Detection of Neural Activity

描述（由申请人提供）： 神经活动期间的瞬时结构变化与动作电位传播直接相关。对这些快速（约1毫秒）和小（约1纳米）变化的第一次非接触式光学测量（Akkin，2003; Akkin等人，2004）最近已经通过使用差分相位对比光学相干断层扫描（DPC-OCT）报道了[1，2]。测量是深度分辨的，不需要外源化学品或反射涂层。该方法在一篇综述文章中被强调为特别感兴趣[3]，是创新的，预计将对神经科学产生重大影响。长期的目标是阐明的瞬态结构变化的起源和它的贡献的光学指标的神经活动。这项工作背后的假设是，活动神经中的瞬时结构变化尽管幅度很小，但却是许多指示神经活动的光学信号的主要贡献者。该假设来自以下观察：（i）1 nm的肿胀比鱿鱼巨轴突报告的延迟变化（AR）大约1，800倍。延迟是双折射（光学性质）和厚度的产物。（ii）非接触式测量显示纳米尺度的溶胀和收缩。类似地，已经报道了不同制剂的延迟和光散射的正变化和负变化，这两者都可能与瞬时厚度变化有关。基于这些观察结果，我们提出的研究的具体目标是将瞬态结构变化与指示神经活动的光学信号相关联。

DESCRIPTION (provided by applicant): Transient structural changes during neural activity are directly related to the action potential propagation. The first non-contact optical measurement of these fast (approximately 1 millisecond) and small (approximately 1 nanometer) changes (Akkin, 2003; Akkin et al., 2004) has been recently reported by using differential phase contrast optical coherence tomography (DPC-OCT) [1,2]. The measurements are depth-resolved and do not require exogenous chemicals or reflection coatings. The method, highlighted as of special interest in a review article [3], is innovative and is expected to have a major impact in neuroscience. The long term objective is to elucidate the origin of the transient structural changes and its contributions to the optical indications of neural activity. The hypothesis behind the work is that the transient structural changes in the active nerve, despite its small magnitude, is a major contributor to many optical signals indicating the neural activity. The hypothesis is derived from the following observations: (i) 1 nm swelling is approximately 1,800 times greater than the retardation change (AR) reported for a squid giant axon. The retardation is the product of birefringence (an optical property) and thickness, (ii) The non-contact measurements revealed nanometer scale swelling and shrinkage. Similarly, positive and negative changes in retardation and light scattering have been reported for different preparations that are both potentially related to the transient thickness change. Based on these observations, the specific aims of our proposed research are designed to correlate the transient structural changes and the optical signals indicating the neural activity.