Cortical plasticity induced by different degrees of peripheral nerve injuries: a rat functional magnetic resonance imaging study under 9.4 Tesla. J Brachial Plex Peripher Nerve Inj 2013 May 09;8(1):4
Date
05/11/2013Pubmed ID
23659705Pubmed Central ID
PMC3659007DOI
10.1186/1749-7221-8-4Scopus ID
2-s2.0-84877115442 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
BACKGROUND: Major peripheral nerve injuries not only result in local deficits but may also cause distal atrophy of target muscles or permanent loss of sensation. Likewise, these injuries have been shown to instigate long-lasting central cortical reorganization.
METHODS: Cortical plasticity changes induced after various types of major peripheral nerve injury using an electrical stimulation technique to the rat upper extremity and functional magnetic resonance imaging (fMRI) were examined. Studies were completed out immediately after injury (acute stage) and at two weeks (subacute stage) to evaluate time affect on plasticity.
RESULTS: After right-side median nerve transection, cortical representation of activation of the right-side ulnar nerve expanded intra-hemispherically into the cortical region that had been occupied by the median nerve representation After unilateral transection of both median and ulnar nerves, cortical representation of activation of the radial nerve on the same side of the body also demonstrated intra-hemispheric expansion. However, simultaneous electrical stimulation of the contralateral uninjured median and ulnar nerves resulted in a representation that had expanded both intra- and inter-hemispherically into the cortical region previously occupied by the two transected nerve representations.
CONCLUSIONS: After major peripheral nerve injury, an adjacent nerve, with similar function to the injured nerve, may become significantly over-activated in the cortex when stimulated. This results in intra-hemispheric cortical expansion as the only component of cortical plasticity. When all nerves responsible for a certain function are injured, the same nerves on the contralateral side of the body are affected and become significantly over-activated during a task. Both intra- and inter-hemispheric cortical expansion exist, while the latter dominates cortical plasticity.
Author List
Li R, Hettinger PC, Machol JA, Liu X, Stephenson JB, Pawela CP, Yan JG, Matloub HS, Hyde JSAuthors
Hani S. Matloub MD Professor in the Plastic Surgery department at Medical College of WisconsinChristopher Pawela PhD Associate Professor in the Biomedical Engineering department at Medical College of Wisconsin
