Li Rupeng, Hettinger Patrick C, Machol Jacques A, Liu Xiping, Stephenson J B, Pawela Christopher P, Yan Ji-Geng, Matloub Hani S, Hyde James S
Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
J Brachial Plex Peripher Nerve Inj. 2013 May 9;8(1):4. doi: 10.1186/1749-7221-8-4.
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.
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.
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.
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.
主要的周围神经损伤不仅会导致局部功能缺损，还可能引起靶肌肉的远端萎缩或感觉的永久性丧失。同样，这些损伤已被证明会引发持久的中枢皮质重组。
使用对大鼠上肢的电刺激技术和功能磁共振成像（fMRI），研究各种类型的主要周围神经损伤后诱导的皮质可塑性变化。在损伤后立即（急性期）和两周后（亚急性期）完成研究，以评估时间对可塑性的影响。
右侧正中神经横断后，右侧尺神经激活的皮质代表在半球内扩展到曾被正中神经代表占据的皮质区域。双侧正中神经和尺神经单侧横断后，身体同侧桡神经激活的皮质代表也显示出半球内扩展。然而，对侧未受伤的正中神经和尺神经同时进行电刺激会导致一种代表，其在半球内和半球间都扩展到先前被两条横断神经代表占据的皮质区域。
主要周围神经损伤后，与受伤神经功能相似的相邻神经在受到刺激时，可能在皮质中显著过度激活。这导致半球内皮质扩展成为皮质可塑性的唯一组成部分。当负责某项功能的所有神经都受伤时，身体对侧的相同神经会受到影响，并在任务期间显著过度激活。半球内和半球间皮质扩展均存在，而后者在皮质可塑性中占主导地位。
