Detection of MR signal modulation due to magnetic fields from axonal currents in the human visual system using LED stimulation
Paley M, Chow L, Cook G, Whitby E
University of Sheffield
The aim of this study is to directly detect axonal currents in the human optic nerve, visual cortex and corpus callosum with LED stimulation using a GE-EPI sequence at 1.5T and 3.0T. It assumes modulation of the MR signal by the magnetic fields of weak axonal currents, which can be detected as image perturbations with the appropriate processing. MR signal fluctuations measured in-vivo are consistent with a Lorentzian model for a symmetrical axonal field distribution within a voxel, from which axonal field strengths have been estimated.