Area-specific synapse structure in branched posterior nucleus axons reveals a new level of complexity in thalamocortical networks

Thalamocortical posterior nucleus (Po) axons innervating the vibrissal somatosensory (S1) and motor (MC) cortices are key links in the brain neuronal network that allows rodents to explore the environment whisking with their motile snout vibrissae. Here, using fine-scale high-end 3D electron microsc...

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Detalles Bibliográficos
Autores: Rodriguez-Moreno, Javier, Porrero Calzado, César, Rollenhagen, Astrid, Rubio-Teves, Mario, Casas-Torremocha, Diana, Alonso-Nanclares, Lidia, Yakoubi, Rachida, Santuy, Andrea, Merchan-Pérez, Angel, DeFelipe, Javier, Lübke, Joachim H.R., Clasca Cabre, Francisco
Tipo de recurso: artículo
Fecha de publicación:2020
País:España
Institución:Universidad Autónoma de Madrid
Repositorio:Biblos-e Archivo. Repositorio Institucional de la UAM
Idioma:inglés
OAI Identifier:oai:repositorio.uam.es:10486/693159
Acceso en línea:http://hdl.handle.net/10486/693159
https://dx.doi.org/10.1523/JNEUROSCI.2886-19.2020
Access Level:acceso abierto
Palabra clave:3D electron microscopy
Mitochondria
Motor cortex
Somatosensory cortex
Synapse
Thalamus
Medicina
Descripción
Sumario:Thalamocortical posterior nucleus (Po) axons innervating the vibrissal somatosensory (S1) and motor (MC) cortices are key links in the brain neuronal network that allows rodents to explore the environment whisking with their motile snout vibrissae. Here, using fine-scale high-end 3D electron microscopy, we demonstrate in adult male C57BL/6 wild-type mice marked differences between MC versus S1 Po synapses in (1) bouton and active zone size, (2) neurotransmitter vesicle pool size, (3) distribution of mitochondria around synapses, and (4) proportion of synapses established on dendritic spines and dendritic shafts. These differences are as large, or even more pronounced, than those between Po and ventro-posterior thalamic nucleus synapses in S1. Moreover, using single-axon transfection labeling, we demonstrate that the above differences actually occur on the MC versus the S1 branches of individual Po cell axons that innervate both areas. Along with recently-discovered divergences in efficacy and plasticity, the synaptic structure differences reported here thus reveal a new subcellular level of complexity. This is a finding that upends current models of thalamocortical circuitry, and that might as well illuminate the functional logic of other branched projection axon systems.

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