Optical Detection of Neural Activity

描述(由申请人提供)： 神经活动过程中的暂时性结构变化与动作电位的传播直接相关。最近通过使用差分相位对比光学相干层析成像(DPC-OCT)首次报道了对这些快速(约1毫秒)和小(约1纳米)变化的非接触光学测量(Akkin，2003；Akkin等人，2004)。测量是深度分辨的，不需要外部化学物质或反光涂层。这一方法在一篇综述文章[3]中被强调为特别感兴趣，是创新的，预计将对神经科学产生重大影响。长期目标是阐明暂时性结构变化的起源及其对神经活动的光学指标的贡献。这项工作背后的假设是，活跃神经中的瞬时结构变化，尽管其幅度很小，但是许多指示神经活动的光学信号的主要贡献者。这一假说源于以下观察：(I)1 nm的肿胀大约是报道的鱿鱼巨大轴突的延迟变化(AR)的1800倍。这种延迟是双折射(一种光学特性)和厚度的产物，(Ii)非接触测量显示纳米级的膨胀和收缩。同样，不同的制剂在延迟和光散射方面也有正负变化的报道，这两者都可能与瞬时厚度变化有关。基于这些观察，我们提出的研究的具体目标是将瞬时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.