Department of Molecular and Systems Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
J Neurosci. 2010 Feb 24;30(8):3082-92. doi: 10.1523/JNEUROSCI.6096-09.2010.
Elucidating neuronal circuits and their plasticity in the cerebral cortex is one of the important questions in neuroscience research. Here we report novel axonal trajectories and their plasticity in the mouse somatosensory barrel cortex. We selectively visualized layer 2/3 neurons using in utero electroporation and examined the axonal trajectories of layer 2/3 neurons. We found that the axons of layer 2/3 neurons preferentially run in the septal regions of layer 4 and named this axonal pattern "barrel nets." The intensity of green fluorescent protein in the septal regions was markedly higher compared with that in barrel hollows. Focal in utero electroporation revealed that the axons in barrel nets were indeed derived from layer 2/3 neurons in the barrel cortex. During development, barrel nets became visible at postnatal day 10, which was well after the initial appearance of barrels. When whisker follicles were cauterized within 3 d after birth, the whisker-related pattern of barrel nets was altered, suggesting that cauterization of whisker follicles results in developmental plasticity of barrel nets. Our results uncover the novel axonal trajectories of layer 2/3 neurons with whisker-related patterns and their developmental plasticity in the mouse somatosensory cortex. Barrel nets should be useful for investigating the pattern formation and axonal reorganization of intracortical neuronal circuits.
阐明大脑皮层中的神经元回路及其可塑性是神经科学研究的重要问题之一。在这里，我们报告了在小鼠体感皮层中新型的轴突轨迹及其可塑性。我们使用子宫内电穿孔选择性地可视化了 2/3 层神经元，并检查了 2/3 层神经元的轴突轨迹。我们发现 2/3 层神经元的轴突优先在 4 层的隔区中运行，并将这种轴突模式命名为“桶状网”。隔区中的绿色荧光蛋白强度明显高于桶状凹陷处。焦点子宫内电穿孔显示，桶状网中的轴突确实来自体感皮层的 2/3 层神经元。在发育过程中，桶状网在出生后第 10 天可见，这远早于桶状结构的最初出现。当出生后 3 天内将胡须滤泡烧焦时，桶状网的胡须相关模式发生改变，表明胡须滤泡的烧焦导致桶状网的发育可塑性。我们的结果揭示了小鼠体感皮层中具有胡须相关模式的 2/3 层神经元的新型轴突轨迹及其发育可塑性。桶状网对于研究皮层内神经元回路的模式形成和轴突重组应该是有用的。
