title: In vivo measurement of cell-type-specific synaptic connectivity and synaptic transmission in layer 2/3 mouse barrel cortex.
abstract: Intracellular recordings of membrane potential in vitro have defined fundamental properties of synaptic communication. Much less is known about the properties of synaptic connectivity and synaptic transmission in vivo. Here, we combined single-cell optogenetics with whole-cell recordings to investigate glutamatergic synaptic transmission in vivo from single identified excitatory neurons onto two genetically defined subtypes of inhibitory GABAergic neurons in layer 2/3 mouse barrel cortex. We found that parvalbumin-expressing (PV) GABAergic neurons received unitary glutamatergic synaptic input with higher probability than somatostatin-expressing (Sst) GABAergic neurons. Unitary excitatory postsynaptic potentials onto PV neurons were also faster and more reliable than inputs onto Sst neurons. Excitatory synapses targeting Sst neurons displayed strong short-term facilitation, while those targeting PV neurons showed little short-term dynamics. Our results largely agree with in vitro measurements. We therefore demonstrate the technical feasibility of assessing functional cell-type-specific synaptic connectivity in vivo, allowing future investigations into context-dependent modulation of synaptic transmission.
authors.affiliation: Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Pala
authors.affiliation: Laboratory of Sensory Processing, Brain Mind Institute, Faculty of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland. Electronic address: carl.petersen@epfl.ch.
authors.forename: Carl C H
authors.initials: CCH
authors.lastname: Petersen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D059330:GABAergic Neurons / Q000166:cytology* / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D051379:Mice; D062308:Optogenetics; D010320:Parvalbumins / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D013003:Somatosensory Cortex / Q000166:cytology* / Q000378:metabolism; D013004:Somatostatin / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D010320:Parvalbumins; D018698:Glutamic Acid; D013004:Somatostatin