Erzurumlu Reha S, Chen Zhou-Feng, Jacquin Mark F
Department of Cell Biology and Anatomy, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Anat Rec A Discov Mol Cell Evol Biol. 2006 Feb;288(2):121-34. doi: 10.1002/ar.a.20285.
The perception of external sensory information by the brain requires highly ordered synaptic connectivity between peripheral sensory neurons and their targets in the central nervous system. Since the discovery of the whisker-related barrel patterns in the mouse cortex, the trigeminal system has become a favorite model for study of how its connectivity and somatotopic maps are established during development. The trigeminal brainstem nuclei are the first CNS regions where whisker-specific neural patterns are set up by the trigeminal afferents that innervate the whiskers. In particular, barrelette patterns in the principal sensory nucleus of the trigeminal nerve provide the template for similar patterns in the face representation areas of the thalamus and subsequently in the primary somatosensory cortex. Here, we describe and review studies of neurotrophins, multiple axon guidance molecules, transcription factors, and glutamate receptors during early development of trigeminal connections between the whiskers and the brainstem that lead to emergence of patterned face maps. Studies from our laboratories and others' showed that developing trigeminal ganglion cells and their axons depend on a variety of molecular signals that cooperatively direct them to proper peripheral and central targets and sculpt their synaptic terminal fields into patterns that replicate the organization of the whiskers on the muzzle. Similar mechanisms may also be used by trigeminothalamic and thalamocortical projections in establishing patterned neural modules upstream from the trigeminal brainstem.
大脑对外部感觉信息的感知需要外周感觉神经元与其在中枢神经系统中的靶标之间具有高度有序的突触连接。自从在小鼠皮层中发现与胡须相关的桶状模式以来，三叉神经系统已成为研究其在发育过程中如何建立连接性和躯体定位图的热门模型。三叉神经脑干核是中枢神经系统中最早由支配胡须的三叉神经传入纤维建立胡须特异性神经模式的区域。特别是，三叉神经主感觉核中的小桶状模式为丘脑面部代表区以及随后的初级躯体感觉皮层中的类似模式提供了模板。在这里，我们描述并综述了在胡须与脑干之间三叉神经连接的早期发育过程中，神经营养因子、多种轴突导向分子、转录因子和谷氨酸受体的研究，这些研究导致了有图案的面部图谱的出现。我们实验室和其他实验室的研究表明，发育中的三叉神经节细胞及其轴突依赖于多种分子信号，这些信号协同引导它们到达适当的外周和中枢靶标，并将其突触终末场塑造成复制口鼻部胡须组织的模式。三叉丘脑和丘脑皮质投射在建立三叉神经脑干上游的有图案神经模块时可能也使用了类似的机制。
