Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation.
OBJECTIVE
Somatosensory evoked potential (SEP) studies suggested that some early cortical SEP components may be generated in the primary motor cortex (M1) rather than the primary somatosensory cortex (S1).


METHODS
We now used functional magnetic resonance imaging (fMRI) to study activation of S1 and M1 by electrical median nerve stimulation in healthy volunteers.


RESULTS
The hand areas of both S1 and M1 showed significant activation (correlation coefficients >0.45) in 7 of 9 subjects (activated volume S1 > M1). For comparison, a sequential finger opposition task significantly activated S1 in 7 and M1 in all 9 subjects (activated volume M1 > S1).


CONCLUSIONS
These data show that the electrical stimuli used for SEP recording lead to a functional activation of S1 as well as M1.
Spiegel
J
J
Institute of Physiology and Pathophysiology, Johannes Gutenberg-University, Mainz, Germany.
Tintera
J
J
Gawehn
J
J
Stoeter
P
P
Treede
R D
RD
D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation; D006801:Humans; D008279:Magnetic Resonance Imaging; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*