Long descending direct projection from the basal ganglia to the spinal cord: a revival of the extrapyramidal concept.
Our retrograde fluorescent labeling study shows that a distinct cell group of the subthalamic nucleus, posited in the basal ganglia, directly sends long descending axons contralaterally to the upper cervical segments (C1-C5) of the spinal cord in the rat. A large population (60-70%) of these subthalamic cells projecting to contralateral spinal levels give off axonal branches innervating the ipsilateral globus pallidus. Now, the classical concept of the 'extrapyramidal' motor system needs to be reconsidered. Furthermore, our results may provide a morphological substrate for the onset of a violent form of dyskinesia, 'hemiballism', which occurs in the contralateral limbs both clinically and experimentally following discrete lesions in the subthalamic nucleus or its fiber connections with the globus pallidus.
Takada
M
M
Department of Anatomy, University of Toronto, Ont. Canada.
Li
Z K
ZK
Hattori
T
T
D000818:Animals; D001479:Basal Ganglia / Q000033:anatomy & histology*; D005116:Extrapyramidal Tracts / Q000033:anatomy & histology*; D005456:Fluorescent Dyes; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D005456:Fluorescent Dyes