title: Anatomy and function of an excitatory network in the visual cortex.
abstract: Circuits in the cerebral cortex consist of thousands of neurons connected by millions of synapses. A precise understanding of these local networks requires relating circuit activity with the underlying network structure. For pyramidal cells in superficial mouse visual cortex (V1), a consensus is emerging that neurons with similar visual response properties excite each other, but the anatomical basis of this recurrent synaptic network is unknown. Here we combined physiological imaging and large-scale electron microscopy to study an excitatory network in V1. We found that layer 2/3 neurons organized into subnetworks defined by anatomical connectivity, with more connections within than between groups. More specifically, we found that pyramidal neurons with similar orientation selectivity preferentially formed synapses with each other, despite the fact that axons and dendrites of all orientation selectivities pass near (<5 μm) each other with roughly equal probability. Therefore, we predict that mechanisms of functionally specific connectivity take place at the length scale of spines. Neurons with similar orientation tuning formed larger synapses, potentially enhancing the net effect of synaptic specificity. With the ability to study thousands of connections in a single circuit, functional connectomics is proving a powerful method to uncover the organizational logic of cortical networks.
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Wei-Chung Allen
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Neuro-Electronics Research Flanders, a research initiative by imec, Vlaams Instituut voor Biotechnologie (VIB) and Katholieke Universiteit (KU) Leuven, 3001 Leuven, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Bonin
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Reed
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Brett J
authors.initials: BJ
authors.lastname: Graham
authors.affiliation: Biomedical Applications Group, Pittsburgh Supercomputing Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Hood
authors.affiliation: Allen Institute for Brain Science, Seattle, Washington 98103, USA.
authors.forename: Katie
authors.initials: K
authors.lastname: Glattfelder
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Allen Institute for Brain Science, Seattle, Washington 98103, USA.
authors.forename: R Clay
authors.initials: RC
authors.lastname: Reid
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002118:Calcium / Q000032:analysis; D003712:Dendrites / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017785:Photons; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology; D013569:Synapses / Q000378:metabolism; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D014795:Visual Pathways / Q000033:anatomy & histology / Q000166:cytology* / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D002118:Calcium