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Topological organization of CA 3‐to‐ CA 1 excitation
Author(s) -
Hongo Yoshie,
Ogawa Koichi,
Takahara Yuji,
Takasu Keiko,
Royer Sebastien,
Hasegawa Minoru,
Sakaguchi Gaku,
Ikegaya Yuji
Publication year - 2015
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.12969
Subject(s) - hippocampal formation , neuroscience , bursting , pyramidal cell , calcium imaging , hippocampus , nerve net , gabaergic , chemistry , biology , inhibitory postsynaptic potential , calcium , organic chemistry
The CA 1‐projecting axons of CA 3 pyramidal cells, called Schaffer collaterals, constitute one of the major information flow routes in the hippocampal formation. Recent anatomical studies have revealed the non‐random structural connectivity between CA 3 and CA 1, but little is known regarding the functional connectivity (i.e. how CA 3 network activity is functionally transmitted downstream to the CA 1 network). Using functional multi‐neuron calcium imaging of rat hippocampal slices, we monitored the spatiotemporal patterns of spontaneous CA 3 and CA 1 burst activity under pharmacological GABA ergic blockade. We found that spatially clustered CA 3 activity patterns were transformed into layered CA 1 activity sequences. Specifically, synchronized bursts initiated from multiple hot spots in CA 3 ensembles, and CA 1 neurons located deeper in the pyramidal cell layer were recruited during earlier phases of the burst events. The order of these sequential activations was maintained across the bursts, but the sequence velocity varied depending on the inter‐burst intervals. Thus, CA 3 axons innervate CA 1 neurons in a highly topographical fashion.