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Selective long‐term reorganization of the corticospinal projection from the supplementary motor cortex following recovery from lateral motor cortex injury
Author(s) -
McNeal David W.,
Darling Warren G.,
Ge Jizhi,
StilwellMorecraft Kimberly S.,
Solon Kathryn M.,
Hynes Stephanie M.,
Pizzimenti Marc A.,
Rotella Diane L.,
Morecraft Robert J.
Publication year - 2009
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.22218
Subject(s) - neuroscience , motor cortex , premotor cortex , primary motor cortex , cortex (anatomy) , neuroplasticity , biology , psychology , anatomy , stimulation , dorsum
Brain injury affecting the frontal motor cortex or its descending axons often causes contralateral upper extremity paresis. Although recovery is variable, the underlying mechanisms supporting favorable motor recovery remain unclear. Because the medial wall of the cerebral hemisphere is often spared following brain injury and recent functional neuroimaging studies in patients indicate a potential role for this brain region in the recovery process, we investigated the long‐term effects of isolated lateral frontal motor cortical injury on the corticospinal projection (CSP) from intact, ipsilesional supplementary motor cortex (M2). After injury to the arm region of the primary motor (M1) and lateral premotor (LPMC) cortices, upper extremity recovery is accompanied by terminal axon plasticity in the contralateral CSP but not the ipsilateral CSP from M2. Furthermore, significant contralateral plasticity occurs only in lamina VII and dorsally within lamina IX. Thus, selective intraspinal sprouting transpires in regions containing interneurons, flexor‐related motor neurons, and motor neurons supplying intrinsic hand muscles, which all play important roles in mediating reaching and digit movements. After recovery, subsequent injury of M2 leads to reemergence of hand motor deficits. Considering the importance of the CSP in humans and the common occurrence of lateral frontal cortex injury, these findings suggest that spared supplementary motor cortex may serve as an important therapeutic target that should be considered when designing acute and long‐term postinjury patient intervention strategies aimed to enhance the motor recovery process following lateral cortical trauma. J. Comp. Neurol. 518:586–621, 2010. © 2009 Wiley‐Liss, Inc.