title: From Cajal to Connectome and Beyond.
abstract: One goal of systems neuroscience is a structure-function model of nervous system organization that would allow mechanistic linking of mind, brain, and behavior. A necessary but not sufficient foundation is a connectome, a complete matrix of structural connections between the nodes of a nervous system. Connections between two nodes can be described at four nested levels of analysis: macroconnections between gray matter regions, mesoconnections between neuron types, microconnections between individual neurons, and nanoconnections at synapses. A long history of attempts to understand how the brain operates as a system began at the macrolevel in the fifth century, was revolutionized at the meso- and microlevels by Cajal and others in the late nineteenth century, and reached the nanolevel in the mid-twentieth century with the advent of electron microscopy. The greatest challenge today is extracting knowledge and understanding of nervous system structure-function architecture from vast amounts of data.
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California 90089; email: lswanson@usc.edu.
authors.forename: Larry W
authors.initials: LW
authors.lastname: Swanson
authors.affiliation: Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138; email: jeff@mcb.harvard.edu.
authors.forename: Jeff W
authors.initials: JW
authors.lastname: Lichtman
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology*; D063132:Connectome / Q000379:methods; D006801:Humans; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
keywords: big data; nervous system; network analysis; neural connections