Gal, EyalLondon, MichaelGloberson, AmirRamaswamy, SrikanthReimann, Michael W.Muller, EilifMarkram, HenrySegev, Idan2017-07-102017-07-102017-07-10201710.1038/nn.4576https://infoscience.epfl.ch/handle/20.500.14299/138918WOS:000404115100017Uncovering structural regularities and architectural topologies of cortical circuitry is vital for understanding neural computations. Recently, an experimentally constrained algorithm generated a dense network reconstruction of a similar to 0.3-mm(3) volume from juvenile rat somatosensory neocortex, comprising similar to 31,000 cells and similar to 36 million synapses. Using this reconstruction, we found a small-world topology with an average of 2.5 synapses separating any two cells and multiple cell-type-specific wiring features. Amounts of excitatory and inhibitory innervations varied across cells, yet pyramidal neurons maintained relatively constant excitation/inhibition ratios. The circuit contained highly connected hub neurons belonging to a small subset of cell types and forming an interconnected cell-type-specific rich club. Certain three-neuron motifs were overrepresented, matching recent experimental results. Cell-type-specific network properties were even more striking when synaptic strength and sign were considered in generating a functional topology. Our systematic approach enables interpretation of microconnectomics 'big data' and provides several experimentally testable predictions.text::journal::journal article::research article