title: Inhibitory Plasticity Permits the Recruitment of CA2 Pyramidal Neurons by CA3
abstract: Area CA2 is emerging as an important region for hippocampal memory formation. However, how CA2 pyramidal neurons (PNs) are engaged by intrahippocampal inputs remains unclear. Excitatory transmission between CA3 and CA2 is strongly inhibited and is not plastic. We show in mice that different patterns of activity can in fact increase the excitatory drive between CA3 and CA2. We provide evidence that this effect is mediated by a long-term depression at inhibitory synapses (iLTD), as it is evoked by the same protocols and shares the same pharmacology. In addition, we show that the net excitatory drive of distal inputs is also increased after iLTD induction. The disinhibitory increase in excitatory drive is sufficient to allow CA3 inputs to evoke action potential firing in CA2 PNs. Thus, these data reveal that the output of CA2 PNs can be gated by the unique activity-dependent plasticity of inhibitory neurons in area CA2.
authors.affiliation: Team Synaptic Plasticity and Neural Networks, FR3636, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8118, Université Paris Descartes , Sorbonne Paris Cité, 75006 Paris, France.
authors.forename: Kaoutsar
authors.initials: K
authors.lastname: Nasrallah
authors.affiliation: Team Synaptic Plasticity and Neural Networks, FR3636, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8118, Université Paris Descartes , Sorbonne Paris Cité, 75006 Paris, France.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Piskorowski
authors.affiliation: Team Synaptic Plasticity and Neural Networks, FR3636, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8118, Université Paris Descartes , Sorbonne Paris Cité, 75006 Paris, France.
authors.forename: Vivien
authors.initials: V
authors.lastname: Chevaleyre
keywords: area CA2; disinhibition; hippocampus; interneuron; long-term depression; δ opioid receptor