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.

R21EB015023

2012-08-01

2015-07-31