Selective and constructive mechanisms contribute to neural circuit formation in the barrel cortex of the developing rat
Selective and constructive mechanisms contribute to neural circuit formation in the barrel cortex of the developing rat作者机构：Cell Biology and Physiology Department Instituto de Investigaciones Biomédicas Universidad Nacional Autónoma de México Mexico City Mexico División de Estudios de Posgrado e Investigación Facultad de Odontología Universidad Nacional Autónoma de México Mexico City Mexico Unidad de HPLC Instituto de Investigaciones Biomédicas Universidad Nacional Autónoma de México Mexico City Mexico
出 版 物：《Advances in Bioscience and Biotechnology》 (生命科学与技术进展（英文）)
年 卷 期：2013年第4卷第7期
页 面：785-797页
学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学]
主 题：Barrel Cortex Synaptogenesis Axonal Growth Dendritic Growth Thalamocortical Pathway
摘 要：The cellular strategy leading to formation of neuronal circuits in the rodent barrel cortex is still a matter of controversy. Both selective and constructive mechanisms have been proposed. The selective mechanism involves an overproduction of neuronal processes and synapses followed by activity dependent pruning. Conversely, a constructive mechanism would increase the number of axons, dendrites, and synapses during development to match functionality. In order to discern the contributions of these two mechanisms in establishing a neuronal circuit in the somatosensory cortex, morphometric analysis of dendritic and axonal arbor growth was performed. Also, the number of synapses was followed by electron microscopy during the first month of life. We observed that axonal and dendritic arbors retracted distal branches, and elongated proximal branches, resulting in increased arbor complexity. This neuronal remodeling was accompanied by the steady increase in the number of synapses within barrel hollows. Similarly, the content of molecular markers for dendrites, axons and synapses also increased during this period. Finally, cytochrome oxidase activity rose with age in barrels indicating that the arbors became more complex while synapse density and metabolic demands increased. Our results support the simultaneous use of both selective and constructive mechanisms in establishing the barrel cortex circuitry.
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