Connectome

A connectome (/kəˈnɛktoʊm/) is a comprehensive map of neural connections in the brain, and may be thought of as its 'wiring diagram'. More broadly, a connectome would include the mapping of all neural connections within an organism's nervous system. A connectome (/kəˈnɛktoʊm/) is a comprehensive map of neural connections in the brain, and may be thought of as its 'wiring diagram'. More broadly, a connectome would include the mapping of all neural connections within an organism's nervous system. The production and study of connectomes, known as connectomics, may range in scale from a detailed map of the full set of neurons and synapses within part or all of the nervous system of an organism to a macro scale description of the functional and structural connectivity between all cortical areas and subcortical structures. The term 'connectome' is used primarily in scientific efforts to capture, map, and understand the organization of neural interactions within the brain. Research has successfully constructed the full connectome of one animal: the roundworm Caenorhabditis elegans (White et al., 1986, Varshney et al., 2011, and Cook et al., 2019). Partial connectomes of a mouse retina and mouse primary visual cortex have also been successfully constructed. Other reconstructions, such as Bock et al.'s 2011 complete 12 terabyte dataset, are publicly available through services such as NeuroData. The ultimate goal of connectomics is to map the human brain. This effort is pursued by the Human Connectome Project, sponsored by the National Institutes of Health (NIH), whose focus is to build a network map of the human brain in healthy, living adults. In 2005, Dr. Olaf Sporns at Indiana University and Dr. Patric Hagmann at Lausanne University Hospital independently and simultaneously suggested the term 'connectome' to refer to a map of the neural connections within the brain. This term was directly inspired by the ongoing effort to sequence the human genetic code—to build a genome. 'Connectomics' (Hagmann, 2005) has been defined as the science concerned with assembling and analyzing connectome data sets. In their 2005 paper, The Human Connectome, a structural description of the human brain, Sporns et al. wrote: In his 2005 Ph.D. thesis, From diffusion MRI to brain connectomics, Hagmann wrote: Pathways through cerebral white matter can be charted by histological dissection and staining, by degeneration methods, and by axonal tracing. Axonal tracing methods form the primary basis for the systematic charting of long-distance pathways into extensive, species-specific anatomical connection matrices between gray matter regions. Landmark studies have included the areas and connections of the visual cortex of the macaque (Felleman and Van Essen, 1991) and the thalamocortical system in the feline brain (Scannell et al., 1999). The development of neuroinformatics databases for anatomical connectivity allow for continual updating and refinement of such anatomical connection maps. The online macaque cortex connectivity tool CoCoMac (Kötter, 2004) and the temporal lobe connectome of the rat are prominent examples of such a database.