title: Sensory-evoked LTP driven by dendritic plateau potentials in vivo.
abstract: Long-term synaptic potentiation (LTP) is thought to be a key process in cortical synaptic network plasticity and memory formation. Hebbian forms of LTP depend on strong postsynaptic depolarization, which in many models is generated by action potentials that propagate back from the soma into dendrites. However, local dendritic depolarization has been shown to mediate these forms of LTP as well. As pyramidal cells in supragranular layers of the somatosensory cortex spike infrequently, it is unclear which of the two mechanisms prevails for those cells in vivo. Using whole-cell recordings in the mouse somatosensory cortex in vivo, we demonstrate that rhythmic sensory whisker stimulation efficiently induces synaptic LTP in layer 2/3 (L2/3) pyramidal cells in the absence of somatic spikes. The induction of LTP depended on the occurrence of NMDAR (N-methyl-d-aspartate receptor)-mediated long-lasting depolarizations, which bear similarities to dendritic plateau potentials. In addition, we show that whisker stimuli recruit synaptic networks that originate from the posteromedial complex of the thalamus (POm). Photostimulation of channelrhodopsin-2 expressing POm neurons generated NMDAR-mediated plateau potentials, whereas the inhibition of POm activity during rhythmic whisker stimulation suppressed the generation of those potentials and prevented whisker-evoked LTP. Taken together, our data provide evidence for sensory-driven synaptic LTP in vivo, in the absence of somatic spiking. Instead, LTP is mediated by plateau potentials that are generated through the cooperative activity of lemniscal and paralemniscal synaptic circuitry.
authors.affiliation: 1] Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland [2] [3] Institute for Interdisciplinary Neuroscience (IINS), UMR 5297 CNRS and University of Bordeaux, 146 rue Léo-Saignat, 33077 Bordeaux, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gambino
authors.affiliation: 1] Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland [2].
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pagès
authors.affiliation: 1] Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland [2] Lemanic Neuroscience Doctoral School, 1 rue Michel Servet, 1211 Geneva, Switzerland.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Kehayas
authors.affiliation: Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland.
authors.forename: Daniela
authors.initials: D
authors.lastname: Baptista
authors.affiliation: 1] Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland [2] Lemanic Neuroscience Doctoral School, 1 rue Michel Servet, 1211 Geneva, Switzerland.
authors.forename: Roberta
authors.initials: R
authors.lastname: Tatti
authors.affiliation: Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland.
authors.forename: Alan
authors.initials: A
authors.lastname: Carleton
authors.affiliation: Department of Basic Neurosciences and the Center for Neuroscience, CMU, University of Geneva, 1 rue Michel Servet, 1211 Geneva, Switzerland.
authors.forename: Anthony
authors.initials: A
authors.lastname: Holtmaat
mesh_terms: D000200:Action Potentials; D000818:Animals; D000075402:Channelrhodopsins; D003712:Dendrites / Q000502:physiology*; D017774:Long-Term Potentiation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010812:Physical Stimulation; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology* / Q000502:physiology*; D013788:Thalamus / Q000166:cytology / Q000502:physiology; D014738:Vibrissae / Q000502:physiology
chemical_list: D000075402:Channelrhodopsins; D016194:Receptors, N-Methyl-D-Aspartate