Label-free 4D optical detection of neural activity

 描述(申请人提供)：理想的神经成像技术将提供精致的结构细节，并提供高空间和时间的功能信息 决议。光学相干层析成像(OCT)是一种光学成像技术，低相干光照射组织，通过干涉仪测量组织内部不同深度微结构的反射率。OCT能够实现微米级的空间分辨率和毫秒级的时间分辨率，无需使用外源造影剂(因此是无标记的)。本应用的目的是开发和验证用于哺乳动物脑功能成像的OCT；将OCT图像与多电极阵列(MEA)评估的细胞电生理相关联；并为基于OCT的神经活动检测提供原理证明。将追求两个具体目标：(1)通过以下方式验证多单元活动(MUA)的检测 海马片光学相干断层扫描(OCT)。我们以前的数据表明，OCT可以检测到与全身性和局灶性癫痫活动相关的同步细胞放电。然而，OCT对多单位活动(MUA)等生理事件的敏感性尚未确定。因此，4-氨基吡啶(4-AP)和高钾诱导的MUA与OCT密切相关。(2)验证OCT对局部刺激诱导的突触激活的检测。为了能够更精确地控制局部刺激的位置和强度，在这个目标中，我们将使用局部刺激海马片中明确的突触路径，并结合基于OCT的检测。从CA3到CA1的Schaffer侧支通路的刺激将通过(1)电刺激和(2)光遗传刺激在CA1触发MUA，然后由MEA检测到MUA，并通过OCT将其与光学信号的变化相关联。我们的方法在将OCT应用于脑功能成像方面具有创新性。这项拟议的研究意义重大，因为它将使OCT作为神经科学研究的神经成像工具得到验证。

 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.