A parturition-associated nonsynaptic coherent activity pattern in the developing hippocampus.
Correlated neuronal activity is instrumental in the formation of networks, but its emergence during maturation is poorly understood. We have used multibeam two-photon calcium microscopy combined with targeted electrophysiological recordings in order to determine the development of population coherence from embryonic to postnatal stages in the hippocampus. At embryonic stages (E16-E19), synchronized activity is absent, and neurons are intrinsically active and generate L-type channel-mediated calcium spikes. At birth, small cell assemblies coupled by gap junctions spontaneously generate synchronous nonsynaptic calcium plateaus associated to recurrent burst discharges. The emergence of coherent calcium plateaus at birth is controlled by oxytocin, a maternal hormone initiating labour, and progressively shut down a few days later by the synapse-driven giant depolarizing potentials (GDPs) that synchronize the entire network. Therefore, in the developing hippocampus, delivery is an important signal that triggers the first coherent activity pattern, which is silenced by the emergence of synaptic transmission.
Crépel
Valérie
V
INMED, INSERM, U29, Université de La Méditerranée, Parc scientifique de Luminy, BP 13, 13273 Marseille Cedex 09, France.
Aronov
Dmitriy
D
Jorquera
Isabel
I
Represa
Alfonso
A
Ben-Ari
Yehezkel
Y
Cossart
Rosa
R
D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002316:Cardiotonic Agents / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D004622:Embryo, Mammalian; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D006624:Hippocampus / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010120:Oxytocics / Q000494:pharmacology; D010121:Oxytocin / Q000494:pharmacology; D036801:Parturition / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011188:Potassium / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*
D002121:Calcium Channel Blockers; D002316:Cardiotonic Agents; D018691:Excitatory Amino Acid Antagonists; D010120:Oxytocics; D011743:Pyrimidines; C082246:ICI D2788; D010121:Oxytocin; D011188:Potassium; D002118:Calcium