There is the old IEEE article on MRI measurement of neuronal current by Dr. Ueno:
"Neuronal current distribution imaging using Magnetic Resonance" , IEEE Transactions on Magnetics, Vol. 5, No 35, 1999, p.4109
Now Bruker biospec resolution is about 30 micrometers in plane. Can we now make an image of neuronal currents in animal brain? Thank you for the articles.
TheMRI calculate the water contents in neurons, white matter and glia.
How is it related to electric currents in axons and dendrites of neuron?
MRI excites some particles (usually hydrogen atoms), and measures the relaxation of their magnetic moments. Neuronal current imaging (NCI) is based on the idea that neuronal currents cause minute but measurable changes in these magnetic moments. In high-field MRI, the large B0 field dwarfs the fields caused by neuronal activity. Therefore it seems that only one-dimensional NCI is possible in high-field MRI. In ultra-low-field MRI, it is possible to switch the B0 field off during the sequence, and do full 3D NCI. As far as I know, this has not been demonstrated in vivo yet, but we are working on it.
I am not a specialist in neurology but I think that neuronal current is alternative current of some frequency (it is seen in EEG). The frequency is small and it gives a rise to J(0) (spectral density of magnetic field fluctuations at zero frequency). We know that only T2 (spin-spin relaxation time) is sensitive to this spectral density. So I have a question. Why do we not see neuronal currents at high field MRI. What "dwarfs" means? Could we use the method of T1 in rotation coordinate system ? Low field MRI is very unsensitive.
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