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Left-right asymmetry of hippocampal synapses and function

Jeudi 27 février 2014 11:30 - Duree : 1 heure
Lieu : Amphithéâtre Serge Kampf, Grenoble Institut des Neurosciences (GIN) - Bât. Edmond J. Safra, Chemin Fortune Ferrini CHU, La Tronche

Orateur : Ryuichi SHIGEMOTO (Institute of Science and Technology Austria, Klosterneuburg, Vienna)

Lateralization of higher brain function in human, such as left hemisphere dominance in language and right hemisphere dominance in spatial learning has long been known. However, very little is known for the mechanism of asymmetry formation in brain compared with that in internal organs. We reported input-side dependent asymmetry of glutamate receptor allocation and synapse structure in mouse hippocampal pyramidal cell synapses. Synapses made on CA1 pyramidal cell spines in the stratum radiatum with left CA3 pyramidal cells have smaller size, less complicated shape, higher density of GluN2B, and lower density of GluA1 than those with right CA3 cells. To elucidate how such asymmetry develops, we examined several kinds of mutant mice. First, situs inversus vicerum (iv) mice, which has randomized lateralization of internal organs showed no input-dependent asymmetry in the hippocampus. Regardless of input side and laterality in internal organs, they showed large size and low density of GluN2B in CA1 stratum radiatum synapses, corresponding to those made by the right input in wild-type mice. Second, we examined beta2-microglobulin knockout mice, which lack MHC class I expression on plasma membrane but have normal laterality in internal organs. They also lacked the input-dependent asymmetry but pyramidal cell synapses in CA1 stratum radiatum showed left input-type for both input sides. These result indicate that lateralization of brain is controlled differently from that of internal organs. Third, CA1-selective GluA1 and GluN2B knockout mice showed small (left-input type) and large (right-input type) synapses, respectively, for both input sides indicating that the synapse size asymmetry is under control of glutamate receptor subunit compositions. Finally, we examined right hemisphere dominance of hippocampal activity after exploration and found that beta2-microglobulin but not iv mutation is involved in this type of functional laterality of the hippocampus.

Contact : jose.martinez-hernandez@inserm.fr

Discipline évènement : (Physique)
Entité organisatrice : (GIN)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire Grenoblois de Neurosciences)
Site de l'évènement : Pôle Santé / La Tronche

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