title: Clusters of synaptic inputs on dendrites of layer 5 pyramidal cells in mouse visual cortex.
abstract: The spatial organization of synaptic inputs on the dendritic tree of cortical neurons plays a major role for dendritic integration and neural computations, yet, remarkably little is known about it. We mapped the spatial organization of glutamatergic synapses between layer 5 pyramidal cells by combining optogenetics and 2-photon calcium imaging in mouse neocortical slices. To mathematically characterize the organization of inputs we developed an approach based on combinatorial analysis of the likelihoods of specific synapse arrangements. We found that the synapses of intralaminar inputs form clusters on the basal dendrites of layer 5 pyramidal cells. These clusters contain 4 to 14 synapses within ≤30 µm of dendrite. According to the spatiotemporal characteristics of synaptic summation, these numbers suggest that there will be non-linear dendritic integration of synaptic inputs during synchronous activation.
authors.affiliation: Department Synapses - Circuits - Plasticity, Max Planck Institute of Neurobiology, Martinsried, Germany.
authors.forename: Onur
authors.identifier: 0000-0002-3913-3893
authors.initials: O
authors.lastname: Gökçe
authors.affiliation: Department Synapses - Circuits - Plasticity, Max Planck Institute of Neurobiology, Martinsried, Germany.
authors.forename: Tobias
authors.identifier: 0000-0001-7897-6634
authors.initials: T
authors.lastname: Bonhoeffer
authors.affiliation: Department Synapses - Circuits - Plasticity, Max Planck Institute of Neurobiology, Martinsried, Germany.
authors.forename: Volker
authors.identifier: 0000-0002-0659-3228
authors.initials: V
authors.lastname: Scheuss
mesh_terms: D000818:Animals; D003712:Dendrites / Q000502:physiology*; D051379:Mice; D008959:Models, Neurological; D061848:Optical Imaging; D062308:Optogenetics; D017966:Pyramidal Cells / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*
keywords: 2-photon calcium imaging; mouse; neuroscience; optogenetics; spatial cluster analysis; synapse cluster; synapse mapping; visual cortex