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Forelimb motor cortical projections in normal rats and after neonatal hemicerebellectomy: An anatomical study based upon the axonal transport of WGA/HRP
Author(s) -
O'Donoghue Daniel L.,
KartjeTillotson Gwendolyn,
Castro Anthony J.
Publication year - 1987
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.902560207
Subject(s) - forelimb , neuroscience , motor cortex , corticospinal tract , biology , anatomy , cerebral cortex , retrograde tracing , pyramidal tracts , efferent , axoplasmic transport , primary motor cortex , cortex (anatomy) , microstimulation , central nervous system , medicine , stimulation , magnetic resonance imaging , radiology , diffusion mri , afferent
Abstract Cerebral cortical projections from the forelimb motor cortex, as defined by intracortical microstimulation where movements were evoked at low current intensities (< 15μA), were examined in normal rats and in adult rats that sustained neonatal hemicerebellectomy. The distribution pattern of cortical efferent projections in normal rats generally appeared more restricted than previously described. This restricted distribution is attributed to the use of WGA/HRP as the axonal tracing method and to the electro‐physiological definition of the injection site as the motor cortex. The observed remodeling of the corticobulbar projections, seen after cerebellar lesions in the young, largely confirmed previous reports. Moreover, no alterations in the laterality of distribution in corticospinal projection were found. Aberrant corticospinal projections were sought in an effort to provide an anatomical basis to a previous description of abnormally low‐threshold ipsilateral forelimb responses evoked from the motor cortex in adult rats after neonatal cerebellar lesions. This apparent absence of corticospinal tract remodeling after neonatal hemicerebellectomy suggests that the abnormal responses are mediated by the normal corticospinal pathways. This possibility is discussed in terms of an alteration in the spinal circuits that may change the responsiveness of spinal motoneurons to a given pyramidal discharge.