Is it possible to detect current in the brain using MRI?

CBR member Brad Roth, of the Department of Physics, recently completed a study to determine if it is possible to detect currents in the brain using magnetic resonance imaging. In collaboration with Ranjith Wijesinghe of Ball State University and his students, Roth published his results in the journal Medical and Biological Engineering and Computing (Volume 50, Pages 651-657). Excerpts from the introduction are given below, with reference removed.

“Many researchers have tried to record neural currents using magnetic resonance imaging (MRI). Such a measurement would be significant, because it would allow functional imaging of neural activity using the high spatial resolution of MRI and avoid an ill-posed inverse problem to determine the current sources. Functional MRI detects brain activity by measuring the blood oxygenation level-dependent (BOLD) signal. Unfortunately, BOLD measures perfusion rather than neural activity directly. Measurement of the magnetic field of neural currents would better follow the distribution of neural activity in time and space. However, the feasibility of detecting neuronal currents by utilizing MRI is a topic that is still under debate. Neuronal mapping with MRI would provide a noninvasive procedure for mapping the active neural pathways in the brain. Different thought processes, motor responses, sensory responses, language, spatial referencing, and cognition to name a few, could be spatially located within the cortical sections of the cerebrum. …Our goal in this paper is to use calculated magnetic signals of dendritic currents to estimate the changes in the MRI signal.”

What did they conclude? "In conclusion, we find that MRI measurements of neural currents in dendrites may be barely detectable using current technology in extreme cases such as seizures, but the chance of detecting normal brain function is very small."

Roth’s research is supported by a grant (R01EB008421) from the National Institute of Biomedical Imaging and Bioengineering, one of the National Institutes of Health.