(Interactive) The C. elegans adult nervous system, neuroanatomy and connectome. Interactive version of Fig. 1 with active links for further information. Top diagrams: the major nerve tracts and ganglia (anterior to left). Not shown are lateral nerves containing the processes of three neurons associated with the canal cell and processes of lateral touch neurons. Hermaphrodite (top) and male (bottom) have the same overall layout. The major difference is a larger number of neurons and muscles in the male tail that sub-serve copulation (see insets). The primary centers of complex connectivity are the nerve ring and, in the male, the pre-anal ganglion (PAG). VG, ventral ganglion; RVG, retrovesicular ganglion; PAG, pre-anal ganglion; DRG, dorsorectal ganglion; LG, lumbar ganglion; CG, cloacal ganglion. Lower diagrams: the nervous system—neuroanatomy and network graph. Top, adult hermaphrodite; bottom, adult male. It is possible to magnify the figure to view the details; mouse over or click on nuclei or nodes to relate them and for pop-up labels and links to information about each cell. (After navigating away from the figure to a website, on return click first on the background before closing the box.) The worm diagrams show the locations of cell nuclei (left side and center only, right-side homologues of left–right pairs are not shown). In the graph representations, the layout of the vertices is determined by an algorithm that clusters more-heavily connected cell pairs (AllegroViva, force-directed strong clustering algorithm). The display is by Cytoscape (cytoscape.org). Directed edges (black arrows) represent chemical synapses; undirected edges (red lines) represent gap junction connections. The widths and transparencies of the lines represent the edge weights. Triangles, sensory neurons; hexagons, interneurons; ovals or circles, motor neurons; rectangles, muscles. Colours define various categories: various reds indicate categories of sensory neurons defined by modality and similarity of connectivity (see also Fig. 3); various blues indicate interneuron categories according to their assignment to a layer (or lack of assignment in the case of IN4) (see also Fig. 2); motor neuron classes (various yellows/oranges) are described in the text; non-muscle end organs are white/grey/black. Sex-specific neurons are pink or purple, with numerous additional colours used for the male-specific network in the male tail, delineating the modules described in ref 3.