Activity-dependent circuit maturation in the neonatal brain: Studies using the mouse barrel cortex

Takuji Iwasato, Ph.D.

National Institute of Genetics, SOKENDAI, Japan

Résumé

Precise neuronal connectivity in the mammalian neocortex is established through refinement during postnatal development. The primary somatosensory cortex (barrel cortex) of the mouse is a useful model to investigate the mechanisms of postnatal circuit maturation. In the mature barrel cortex, the configuration of whiskers on the face is topographically represented as “barrels”, discrete modules of layer 4 neurons and thalamocortical (TC) axon terminals. Spiny stellate cells, the major type of layer 4 excitatory neurons, that are located at the barrel edge expand basal dendrites asymmetrically toward the barrel center to form synapses with specific TC axons, which underlies the precise one-to-one functional relationship between whiskers and barrels. Importantly, these features of the whisker-barrel circuit are established essentially during the first postnatal week in a manner depending on presynaptic TC inputs and postsynaptic NMDA receptor functions. For decades, we have been using the mouse barrel cortex for the study of developmental plasticity by developing and adopting several original approaches (e.g. Iwasato et al., Neuron 1997, Nature 2000; Mizuno et al., Neuron 2014; Luo et al, Sci. Rep. 2017; Nakazawa et al., Nature Commun. 2018). In this seminar, I would like to discuss our recent findings by primarily focusing on mechanisms of dendritic refinement of barrel cortex layer 4 neurons.

Invité par Aurélien Fortoul et Neuroschool

Lundi 22 mai à 11h – salle de conférence de l’Inmed