Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation
Objectives:
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.
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Somatosensation
Motor and Sensory Areas of the Cortex
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