Journal of Neuroscience, Vol 6, 463-474, Copyright © 1986 by Society for Neuroscience
Functional metabolic mapping during forelimb movement in rat. II. Stimulation of forelimb muscles
EM Santori, T Der and RC Collins
Repetitive electrical stimulation of wrist extensor muscles in rat was
combined with quantitative 14C-deoxyglucose autoradiography to study
sensory systems functionally activated during forelimb movement. Metabolism
increased ipsilaterally in the wrist extensors, the dorsal horn of the
cervical spinal cord, the cuneate nucleus and cerebellar hemisphere. The
metabolic activation in cerebellum occurred in cortex surrounding the
primary fissure anteriorly (lobules simplex and V), and the prepyramidal
fissure posteriorly (lobules paramedian and copula pyramis). Metabolism was
increased in both granule cell and molecular layers and was uniform
throughout the zone of activation. Hindlimb stimulation primarily activated
the medial aspect of copula pyramis, demonstrating the somatotopic
specificity of changes. Forelimb stimulation also activated contralateral
sites in the dorsal accessory nucleus of the inferior olive, ventrobasal
thalamus, and SI and SII in cortex. Studies of the relationship between the
magnitude of the response and the frequency of the stimulation revealed a
positive correlation in muscle, dorsal horn and cuneate nucleus. Other
activated sites only showed a significant change at the highest rates of
stimulation. Comparison of the pattern of metabolic activation during
forelimb movements induced centrally (Collins et al., 1986) with the
pattern induced peripherally revealed overlap primarily in the paramedian
zone of anterior and posterior cerebellum, and the granular cortex of SI
and SII. These studies suggest that forelimb movement initiated centrally
would have considerable influence on feedback sensation from the moving
limb in these sites.