In Vivo Measurements of Physiologically-evoked Neuronal Currents

描述(申请人提供)：本项目的目标是以章鱼作为活体动物模型，探索磁共振成像直接检测正常感觉刺激引起的神经元电流的能力。原则上，神经元电流磁共振成像(NcMRI)比现有的基于血流动力学的功能磁共振成像方法提供了更好的时空分辨率。然而，关于在人类受试者中检测到ncMRI信号的相互矛盾的报告使得ncMRI的可行性成为一个悬而未决的问题。由于以前的大多数人类ncMRI研究由于无法分离或消除血流动力学影响而存在问题，目前还不可能得出ncMRI是否可行的结论。为了令人信服地解决这一长期存在的争论，我们将在章鱼身上检测视觉诱发的ncMRI信号。章鱼有一个很大的大脑和高度发达的视觉系统，但它的血液不会产生任何依赖于血氧水平(BOLD)的对比。因此，它是一种理想的体内动物模型，用于测量无大胆污染的ncMRI。提出的ncMRI是一项旨在直接成像神经元电流的创新技术。它将神经元中的电生理事件与传统MRI技术提供的大神经元群体的系统水平视图联系起来，应该会产生很大的影响。这一拟议研究项目的成功开发将解决长期存在的关于ncMRI可行性的争论。具体地说，任何ncMRI信号的检测将使我们第一次能够描述神经元电流成像的时间和空间特征。这些测量反过来将为获取策略和对未来人类ncMRI实验的解释提供必要的基础。

DESCRIPTION (provided by applicant): The goal of this project is to use octopus as an in vivo animal model to explore the ability of MRI to directly detect the neuronal electrical currents evoked by normal sensory stimulation. In principle, neuronal current MRI (ncMRI) offers improved spatio-temporal resolution over current hemodynamic-based functional MRI methods. However, contradictory reports regarding the detection of ncMRI signal in human subjects have left the feasibility of ncMRI an open question. Since most previous human ncMRI studies are problematic due to their inability to separate or eliminate hemodynamic effects, no conclusion is yet been possible whether ncMRI is achievable. To resolve this long-standing debate convincingly, we will detect visually evoked ncMRI signals in the octopus. The octopus has a large brain and a highly developed visual system, but its blood does not produce any blood oxygen level dependent (BOLD) contrast. Therefore, it is an ideal in vivo animal model for measuring ncMRI without BOLD contamination. The proposed ncMRI is an innovative technology that aims to image neuronal electrical currents directly. It should have a high impact by connecting the electrophysiological events in neurons with the systems-level view of large neuronal populations afforded by conventional MRI techniques. Successful development of this proposed research project will resolve the long-standing debate on the feasibility of ncMRI. Specifically, detection of any ncMRI signal will enable us, for the first time, to describe the temporal and spatial characteristics of neuronal current imaging. These measurements, in turn, will provide the necessary foundation for acquisition strategies and interpretations of future human ncMRI experiments.