Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
Neuron. 2012 May 24;74(4):731-42. doi: 10.1016/j.neuron.2012.04.024.
Experience-dependent plasticity in the adult brain has clinical potential for functional rehabilitation following central and peripheral nerve injuries. Here, plasticity induced by unilateral infraorbital (IO) nerve resection in 4-week-old rats was mapped using MRI and synaptic mechanisms were elucidated by slice electrophysiology. Functional MRI demonstrates a cortical potentiation compared to thalamus 2 weeks after IO nerve resection. Tracing thalamocortical (TC) projections with manganese-enhanced MRI revealed circuit changes in the spared layer 4 (L4) barrel cortex. Brain slice electrophysiology revealed TC input strengthening onto L4 stellate cells due to an increase in postsynaptic strength and the number of functional synapses. This work shows that the TC input is a site for robust plasticity after the end of the previously defined critical period for this input. Thus, TC inputs may represent a major site for adult plasticity in contrast to the consensus that adult plasticity mainly occurs at cortico-cortical connections.
成人脑的经验依赖性可塑性具有中枢和周围神经损伤后功能康复的临床潜力。在这里，通过对 4 周大的大鼠眶下神经（IO）单侧切除术来绘制 MRI 诱导的可塑性，并通过切片电生理学阐明了突触机制。与丘脑相比，IO 神经切除后 2 周，功能 MRI 显示皮质增强。用锰增强 MRI 追踪丘脑皮质（TC）投射显示，在未受损的第 4 层（L4）桶状皮层中存在回路变化。脑切片电生理学显示，由于突触后强度和功能性突触数量的增加，TC 输入增强到 L4 星状细胞上。这项工作表明，TC 输入是在先前定义的该输入关键期结束后发生强大可塑性的一个部位。因此，TC 输入可能代表成人可塑性的主要部位，与成人可塑性主要发生在皮质-皮质连接的共识形成对比。
