Effect of nerve cell currents on MRI images in snail ganglia.

We performed extracellular potential recording with dissected snail ganglia inside an MRI scanner to investigate correlation between neuronal activity and MR image intensity. To increase neuronal activity we applied a nitric oxide donor, sodium-nitrosocystein, to the ganglia. The MR image intensity change in the ganglia region is correlated with the neuronal activity and was up to 5.49+/-1.94%. Since the snail has non-magnetic hemocyanins as oxygen carrying protein, it seems that the image intensity change is mainly due to the local magnetic fields produced by the neuronal currents.