Information processing limits on generating neuroanatomy: global optimization of rat olfactory cortex and amygdala.

A pattern of widespread connection optimization in the nervous system has become evident: deployment of some neural interconnections attains optimality, sometimes without detectable limits. New results for optimization of layout of connected areas of rat olfactory cortex and of rat amygdala are reported here. One larger question concerns mechanisms-how such minimization is attained. A next question is why a nervous system would optimize rather than just moderately satisfice. A morphogenic proposal that relates these questions is that the means of organizing neural wiring happens also to yield optimization. Some neuroanatomy is generated via "saving wire," and this optimizing is via simple physical processes rather than DNA-mediated mechanisms. Such "non-genomic nativism" is thereby a path around fundamental limitations on generating brains, some of the most complex structures in the known universe.