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Regional ( 14 C) 2‐deoxyglucose uptake during forelimb movements evoked by rat motor cortex stimulation: Pons, cerebellum, medulla, spinal cord, muscle
Author(s) -
Sharp Frank R.,
Ryan Allen F.
Publication year - 1984
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902240208
Subject(s) - spinal cord , anatomy , lateral reticular nucleus , pontine nuclei , pons , cerebellum , dorsal column nuclei , lateral funiculus , cerebellar cortex , reticular formation , forelimb , biology , inferior olivary nucleus , neuroscience , deep cerebellar nuclei , medulla oblongata , red nucleus , stimulation , nucleus , central nervous system
Electrical stimulation of the right forelimb motor (MI) sensory (SI) cortex in normal, adult rats produced repetitive left forelimb movements. Regions of increased ( 14 C) 2‐deoxyglucose (2DG) uptake were mapped autoradiographically during these movements. MI stimulation activated the ipsilateral reticular tegmental pontine nucleus (RTF) and the middle (rostral‐caudal) third of the pontine nuclei including pyramidal (P), medial (POM), ventral (POV), and lateral (POL) pontine nuclei. The ipsilateral inferior olivary complex was activated including dorsal accessory olive (DAO), principal olive (PO), and medial accessory olive (MAO). The contralateral lateral reticular (LR) nucleus and nucleus cuneatus (CU) were activated. Lateral vermal, paravermal, and hemispheric portions of the contralateral cerebellum were also activated. Parts of vermian lobules IV, V, VI, VII, and VIII, and lobulus simplex, crus I, crus II, paramedian lobule, and copula pyramidis were activated. Granule cell layers were activated much more than molecular layers. Discrete microzones of high granule cell 2DG uptake alternated with zones of low uptake in left paramedian lobule and copula pyramidis and may correlate with the fractured cerebellar somatotopy described physiologically by Welker and his associates. Portions of the left lateral and interpositus nuclei were metabolically activated. Medial portions of laminae I‐VI were activated in the dorsal horn of cervical spinal cord. The 2DG uptake was either unchanged or decreased in the ventral horn. Thoracic and lumbar spinal cord were not activated. Monsynaptic MI and SI connections to P, POM, POV, POL, RTF, DAO, PO, MAO, LR, CU, and spinal cord could account for activation of those structures. However, there are no direct MI or SI connections to the deep cerebellar nuclei, the cerebellar hemisphere, or the muscles. Activation of these structures must be due to activation of polysynaptic pathways, sensory feedback from the moving forelimb, or both. The present experiments cannot distinguish these possibilities. Comparison of the regions activated during forelimb MI stimulation (FLMIS) to those activated during vibrissae MI stimulation (VMIS) suggests that the pontine nuclei, cerebellar hemisphere, and possibly the deep cerebellar nuclei are somatotopically organized. RTP, LR, CU, and spinal cord were activated during FLMIS but were not activated during VMIS. The failure to activate the ventral horn of cervical spinal cord may be due to known inhibition of alpha‐motor neurons during motor cortex stimulation.