Open Access
J Brachial Plex Peripher Nerve Inj 2013; 08(01): e8-e18
DOI: 10.1186/1749-7221-8-4
Research article
Li et al.; licensee BioMed Central Ltd.

Cortical plasticity induced by different degrees of peripheral nerve injuries: a rat functional magnetic resonance imaging study under 9.4 Tesla[*]

Rupeng Li
1   Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
,
Patrick C Hettinger
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
Jacques A Machol
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
Xiping Liu
3   Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
,
J B Stephenson IV
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
Christopher P Pawela
1   Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
Ji-Geng Yan
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
Hani S Matloub
2   Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
,
James S Hyde
1   Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
› Author Affiliations

Subject Editor:
Further Information

Publication History

29 October 2012

25 April 2013

Publication Date:
25 September 2014 (online)

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Abstract

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.

*This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.