Spatial distribution of hand-grip motor task activity in spinal cord fMRI

A unilateral isometric hand-grip task was used to elicit motor neuron activation in spinal cord fMRI. As predicted, activation was lateralized to the ipsilateral hemicord. However, active voxels were also observed outside of the ventral horn and superior to C7. Reduced spatial precision and sensitivity in activation estimates, particularly along the cord axis, may be due to the combination of inter-individual differences in anatomy, imperfect registration to the standard spinal cord template, additional sensory activity associated with performing the task, and co-contraction of muscles not directly involved in hand-gripping.