title: Directly mapping magnetic field effects of neuronal activity by magnetic resonance imaging.
abstract: Magnetic resonance imaging (MRI) of brain functional activity relies principally on changes in cerebral hemodynamics, which are more spatially and temporally distributed than the underlying neuronal activity changes. We present a novel MRI technique for mapping brain functional activity by directly detecting magnetic fields induced by neuronal firing. Using a well-established visuomotor paradigm, the locations and latencies of activations in visual, motor, and premotor cortices were imaged at a temporal resolution of 100 msec and a spatial resolution of 3 mm, and were found to be in consistent with the electrophysiological and functional MRI (fMRI) literature. Signal strength was comparable to traditional event-related fMRI methods: about 1% of the baseline signal. The magnetic-source MRI technique greatly increases the temporal accuracy in detecting neuronal activity, providing a powerful new tool for mapping brain functional organization in human and animals.
authors.affiliation: Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Jinhu
authors.initials: J
authors.lastname: Xiong
authors.forename: Peter T
authors.initials: PT
authors.lastname: Fox
authors.forename: Jia-Hong
authors.initials: JH
authors.lastname: Gao
mesh_terms: D000200:Action Potentials; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000502:physiology*