Finding neuroelectric activity under magnetic-field oscillations (NAMO) with magnetic resonance imaging in vivo

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Abstract
Neuroimaging techniques are among the most important tools for investigating the function of the human nervous system and for improving the clinical diagnosis of neurological disorders. However, most commonly used techniques are limited by their invasiveness or their inability to accurately localize neural activity in space or time. Previous attempts at using MRI to directly image neuroelectric activity in vivo through the detection of magnetic field changes induced by neuronal currents have been challenging because of the extremely small signal changes and confounding factors such as hemodynamic modulations. Here we describe an MRI technique that uses oscillating magnetic field gradients to significantly amplify and detect the Lorentz effect induced by neuroelectric activity, and we demonstrate its effectiveness in imaging sensory nerve activation in vivo in the human median nerve during electrical stimulation of the wrist. This direct, real-time, and noninvasive neuroimaging technique may potentially find broad applications in neurosciences.