In Vivo Measurements of Physiologically-evoked Neuronal Currents

项目描述（由申请人提供）：本项目以章鱼为活体动物模型，探索MRI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MRI （ncMRI）比当前基于血流动力学的功能MRI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ncMRI信号的相互矛盾的报告使ncMRI的可行性成为一个悬而未决的问题。由于大多数先前的人类ncMRI研究都存在问题，因为它们无法分离或消除血流动力学效应，因此ncMRI是否可以实现尚无结论。为了令人信服地解决这个长期存在的争论，我们将在章鱼中检测视觉诱发的ncMRI信号。章鱼有很大的大脑和高度发达的视觉系统，但它的血液不产生任何依赖于血氧水平（BOLD）的对比度。因此，它是一种理想的体内动物模型，用于测量没有BOLD污染的ncMRI。提出的ncMRI是一项创新技术，旨在直接成像神经元电流。通过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的系统级视图联系起来，它应该具有很高的影响。这一拟议研究项目的成功发展将解决长期以来关于ncMRI可行性的争论。具体来说，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。反过来，这些测量将为未来人类ncMRI实验的获取策略和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.