Label-free 4D optical detection of neural activity

 描述（由申请人提供）：理想的神经成像技术将提供精致的结构细节，并提供功能信息，具有高度的空间和时间 分辨率光学相干断层扫描（OCT）是一种光学成像技术，其中来自低相干源的光照射组织，并且通过干涉仪测量不同深度处的内部微结构的反射率。OCT能够达到微米级空间分辨率和毫秒级时间分辨率，无需使用外源性造影剂（因此是“无标记”）。本申请的目的是开发和验证用于哺乳动物脑功能成像的OCT;将OCT图像与通过多电极阵列（MEA）评估的细胞电生理学相关联;并为基于OCT的神经活动检测提供原理验证。将追求两个具体目标：（1）通过以下方法对多单元活动（MUA）进行快速检测： 海马切片中的光学相干断层扫描（OCT）。我们以前的数据表明，OCT可以检测与全身性和局灶性癫痫发作活动相关的同步细胞放电。然而，OCT对多单位活动（MUA）等生理事件的灵敏度尚未确定。（2）OCT对局部刺激诱导的突触激活的快速检测。为了更精确地控制局部刺激的部位和强度，我们将在海马脑片中使用特定突触通路的局部刺激结合OCT检测。从CA 3到CA 1的Schaffer侧支通路的刺激将通过（1）电刺激和（2）光遗传学刺激来进行，以触发CA 1中的MUA，然后通过MEA检测并通过OCT与光学信号的变化相关联。我们的方法在使OCT适应脑功能成像方面具有创新性。这项研究意义重大，因为它将导致OCT作为神经科学研究的神经成像工具的有效性。

 DESCRIPTION (provided by applicant): The ideal neuroimaging technique would provide exquisite structural detail and also provide functional information, with high spatial and temporal resolution. Optical coherence tomography (OCT) is an optical imaging technique in which light from a low coherent source illuminates tissue and reflectivity of internal microstructures at different depths is measured by an interferometer. OCT is capable of micrometer-spatial and millisecond-temporal resolutions, without the use of exogenous contrast agents (hence "label-free"). The objective in this application is to develop and validate OCT for mammalian brain functional imaging; correlate OCT images with cellular electrophysiology assessed by multielectrode array (MEA); and provide proof-of- principle for OCT-based detection of neural activity. Two specific aims will be pursued: (1) Validate detection of multi-unit activity (MUA) by optical coherence tomography (OCT) in hippocampal slices. Our previous data demonstrate that OCT can detect synchronous cellular firing associated with both generalized and focal seizure activity. However, the sensitivity of OCT to physiological events such as multiunit activity (MUA) has not yet been determined. In this Aim, MUA induced by 4-aminopyridine (4-AP) and high K+ will be correlated to OCT. (2) Validate detection of local stimulation-induced synaptic activation by OCT. To allow more precise control of local stimulation site and intensity, in this Aim we will use local stimulation of a defined synaptic pathway in the hippocampal slice combined with OCT-based detection. Stimulation of the Schaffer collateral pathway from CA3 to CA1 will be performed by (1) electrical stimulation and (2) optogenetic stimulation to trigger MUA in CA1 that will be then detected by MEA and correlated to the changes in the optical signal by OCT. Our approach is innovative in adapting OCT for brain functional imaging. The proposed research is significant because it will lead to the validation of OCT as a neuroimaging tool for research in neuroscience.