1Department of Radiology, Michigan State University, East Lansing, MI, United States
Neural activity associated local neuronal currents produce weak transient magnetic fields that would attenuate local MR signal intensity. There is not yet consensus as to whether the size of this attenuation is detectable with the current MRI techniques. Some groups have reported a successful detection of neuronal currents using MRI, but other groups failed to detect the activity. This study investigates the magnitude of the neuronal current-induced signal attenuation using a temporally well-controlled visual stimulation paradigm. The results show that the visual stimulus-evoked neuronal currents in the visual cortex do not induce detectable signal attenuation with the current MRI technique.