Iwasato T, Datwani A, Wolf A M, Nishiyama H, Taguchi Y, Tonegawa S, Knöpfel T, Erzurumlu R S, Itohara S
Laboratory for Behavioral Genetics, Brain Science Institute, RIKEN, Saitama, Japan.
Nature. 2000 Aug 17;406(6797):726-31. doi: 10.1038/35021059.
In the rodent primary somatosensory cortex, the configuration of whiskers and sinus hairs on the snout and of receptor-dense zones on the paws is topographically represented as discrete modules of layer IV granule cells (barrels) and thalamocortical afferent terminals. The role of neural activity, particularly activity mediated by NMDARs (N-methyl-D-aspartate receptors), in patterning of the somatosensory cortex has been a subject of debate. We have generated mice in which deletion of the NMDAR1 (NR1) gene is restricted to excitatory cortical neurons, and here we show that sensory periphery-related patterns develop normally in the brainstem and thalamic somatosensory relay stations of these mice. In the somatosensory cortex, thalamocortical afferents corresponding to large whiskers form patterns and display critical period plasticity, but their patterning is not as distinct as that seen in the cortex of normal mice. Other thalamocortical patterns corresponding to sinus hairs and digits are mostly absent. The cellular aggregates known as barrels and barrel boundaries do not develop even at sites where thalamocortical afferents cluster. Our findings indicate that cortical NMDARs are essential for the aggregation of layer IV cells into barrels and for development of the full complement of thalamocortical patterns.
在啮齿动物的初级体感皮层中，口鼻部的触须和鼻窦毛以及爪子上受体密集区的构型，在地形学上表现为IV层颗粒细胞（桶状结构）和丘脑皮质传入终末的离散模块。神经活动，特别是由NMDARs（N-甲基-D-天冬氨酸受体）介导的活动，在体感皮层模式形成中的作用一直是一个争论的话题。我们培育出了NMDAR1（NR1）基因缺失仅限于兴奋性皮层神经元的小鼠，并且在此我们表明，在这些小鼠的脑干和丘脑体感中继站中，与感觉外周相关的模式正常发育。在体感皮层中，对应于大型触须的丘脑皮质传入纤维形成模式并表现出关键期可塑性，但其模式形成不如正常小鼠皮层中那样明显。对应于鼻窦毛和趾的其他丘脑皮质模式大多不存在。即使在丘脑皮质传入纤维聚集的部位，称为桶状结构和桶状边界的细胞聚集体也不会发育。我们的研究结果表明，皮层NMDARs对于IV层细胞聚集成桶状结构以及丘脑皮质模式的完整形成至关重要。
