How well do "Save wire" concepts from combinatorial network optimization theory fit as models for brain anatomy? One result concerns ganglion
placement in the nervous system of C. elegans: Our exhaustive searches indicate that the actual layout of the ganglia in the roundworm requires less total interconnecting wirelength than any of the 40 million other possible layouts -- a predictive success story. For the corresponding, but combinatorially intractable, question of interconnection wire- minimization in placement of the areas on the cerebral cortex sheet, we tested instead an "Adjacency Rule": If components a and b are interconnected, then they are contiguous. If cortical components are placed to minimize total interconnection costs, one would expect conformation to this rule; we found strong support for both macaque and cat visual cortex, as well as C. elegans ganglia. [ MH49867 9/91 3.0 ] (UMIACS-TR-2003-92)