Bazley Faith A, All Angelo H, Thakor Nitish V, Maybhate Anil
Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:2005-8. doi: 10.1109/IEMBS.2011.6090564.
Spinal cord injury (SCI) causes a number of physiological and neurological changes resulting in loss of sensorimotor function. Recent work has shown that the central nervous system is capable of plastic behaviors post-injury, including axonal regrowth and cortical remapping. Functional integrity of afferent sensory pathways can be quantified using cortical somatosensory evoked potentials (SSEPs) recorded upon peripheral limb stimulation. We implanted 15 rats with transcranial screw electrodes and recorded SSEPs from cortical regions corresponding to each limb before and after a mild or moderate contusion injury. We report a post-injury increase in the mean amplitude of cortical SSEPs upon forelimb stimulation. SSEP amplitudes for mild and moderate SCI groups increased by 183% ± 95% and 107% ± 38% over baseline, respectively, while hindlimb SSEPs decreased by 58% ± 14% and 79% ± 4%. In addition, we report increased SSEP amplitude measured from the anatomically adjacent hindlimb region upon forelimb stimulation (increase of 90% ± 19%). Our results show that previously allocated hindlimb cortical regions are now activated by forelimb stimulation, suggesting an expansion in the area of cortical forelimb representation into hindlimb regions after an injury. This result is indicative of adaptive plasticity in undamaged areas of the CNS following SCI.
脊髓损伤（SCI）会引发一系列生理和神经学变化，导致感觉运动功能丧失。最近的研究表明，中枢神经系统在损伤后具有可塑性行为，包括轴突再生和皮质重新映射。传入感觉通路的功能完整性可以通过在肢体外周刺激时记录的皮质体感诱发电位（SSEPs）来量化。我们给15只大鼠植入了经颅螺钉电极，并在轻度或中度挫伤性损伤前后记录了对应于每个肢体的皮质区域的SSEPs。我们报告了前肢刺激后皮质SSEPs平均振幅的损伤后增加。轻度和中度SCI组的SSEP振幅分别比基线增加了183%±95%和107%±38%，而后肢SSEPs分别下降了58%±14%和79%±4%。此外，我们报告了在前肢刺激时从解剖学上相邻的后肢区域测量到的SSEP振幅增加（增加了90%±19%）。我们的结果表明，先前分配给后肢的皮质区域现在被前肢刺激激活，这表明损伤后皮质前肢代表区域扩展到了后肢区域。这一结果表明脊髓损伤后中枢神经系统未受损区域存在适应性可塑性。
