Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892;
Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Proc Natl Acad Sci U S A. 2019 Mar 26;116(13):6391-6396. doi: 10.1073/pnas.1810132116. Epub 2019 Mar 7.
Central or peripheral injury causes reorganization of the brain's connections and functions. A striking change observed after unilateral stroke or amputation is a recruitment of bilateral cortical responses to sensation or movement of the unaffected peripheral area. The mechanisms underlying this phenomenon are described in a mouse model of unilateral whisker deprivation. Stimulation of intact whiskers yields a bilateral blood-oxygen-level-dependent fMRI response in somatosensory barrel cortex. Whole-cell electrophysiology demonstrated that the intact barrel cortex selectively strengthens callosal synapses to layer 5 neurons in the deprived cortex. These synapses have larger AMPA receptor- and NMDA receptor-mediated events. These factors contribute to a maximally potentiated callosal synapse. This potentiation occludes long-term potentiation, which could be rescued, to some extent, with prior long-term depression induction. Excitability and excitation/inhibition balance were altered in a manner consistent with cell-specific callosal changes and support a shift in the overall state of the cortex. This is a demonstration of a cell-specific, synaptic mechanism underlying interhemispheric cortical reorganization.
中枢或外周损伤导致大脑连接和功能的重组。在单侧中风或截肢后观察到的一个显著变化是，对未受影响的外周区域的感觉或运动的双侧皮质反应的募集。在单侧胡须剥夺的小鼠模型中描述了这种现象的机制。刺激完整的胡须会在体感桶状皮层中产生双侧血氧水平依赖性 fMRI 反应。全细胞电生理学表明，完整的桶状皮层选择性地增强了到剥夺皮层的第 5 层神经元的胼胝体突触。这些突触具有更大的 AMPA 受体和 NMDA 受体介导的事件。这些因素有助于最大程度地增强胼胝体突触。这种增强会阻断长时程增强，而通过预先诱导长时程抑制，可以在一定程度上挽救这种阻断。兴奋性和兴奋/抑制平衡发生改变，与细胞特异性胼胝体变化一致，并支持皮质整体状态的转变。这证明了大脑半球间皮质重组的一种细胞特异性、突触机制。
