Pelled Galit, Chuang Kai-Hsiang, Dodd Stephen J, Koretsky Alan P
Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, B1D728, 10 Center Drive, Bethesda, MD, USA.
Neuroimage. 2007 Aug 1;37(1):262-73. doi: 10.1016/j.neuroimage.2007.03.069. Epub 2007 Apr 25.
Evidence is emerging for significant inter-hemispheric cortical plasticity in humans, opening important questions about the significance and mechanism for this long range plasticity. In this work, peripheral nerve deafferentation was performed on both the rat forepaw and hindpaw and cortical reorganization was assessed using functional MRI (fMRI). Sensory stimulation of the forepaw or the hindpaw in rats that experienced only partial denervation resulted in activation in only the appropriate, contralateral, primary somatosensory cortex (SI). However, 2-3 weeks following complete denervation of the rats' forepaw or hindpaw, stimulation of the intact paw resulted in fMRI activation of ipsilateral as well as contralateral SI. To address whether inter-cortical communication is required for this cortical reorganization, the healthy hindpaw SI representation was stereotaxically lesioned in rats which had the other hindpaw denervated. No fMRI activation was detected in the ipsilateral SI cortex after lesioning of the contralateral cortex. These results indicate that extensive inter-hemispheric cortical-cortical reorganization can occur in the rodent brain after peripheral nerve deafferentation and that cortical-cortical connections play a role in mediating this inter-hemispheric cortical reorganization.
越来越多的证据表明人类大脑半球间存在显著的皮质可塑性，这引发了关于这种远距离可塑性的意义和机制的重要问题。在这项研究中，对大鼠的前爪和后爪进行了外周神经去传入手术，并使用功能磁共振成像（fMRI）评估皮质重组情况。仅经历部分去神经支配的大鼠，对其前爪或后爪进行感觉刺激，仅在相应的对侧初级体感皮层（SI）引发激活。然而，在大鼠的前爪或后爪完全去神经支配2 - 3周后，对完整爪子的刺激在同侧以及对侧SI均引发了fMRI激活。为了探究这种皮质重组是否需要皮质间的通信，在另一只后爪去神经支配的大鼠中，对健康后爪的SI表征进行立体定向损伤。对侧皮质损伤后，同侧SI皮质未检测到fMRI激活。这些结果表明，外周神经去传入后，啮齿动物大脑中可发生广泛的半球间皮质 - 皮质重组，且皮质 - 皮质连接在介导这种半球间皮质重组中发挥作用。
