Progress and perspectives in computational neuroanatomy

The tremendous increase in processing power of personal computers has recen tly allowed the construction of highly sophisticated models of neuronal fun ction and behavior. Anatomy plays a fundamental role in supporting and shap ing nervous system activity, yet to date most details of such a role have e scaped the efforts of experimental and theoretical neuroscientists, mainly because of the problem's complexity. When accurate cellular morphologies ar e included in electrophysiological computer simulations, quantitative and q ualitative effects of dendritic structure on firing properties can be exten sively characterized. Complete models of dendritic morphology can be implem ented to allow the computer generation of virtual neurons that model the an atomical characteristics of their real counterparts to a great degree of ap proximation. From a restricted and already available experimental database, stochastic and statistical algorithms can create an unlimited number of no n-identical virtual neurons within several mammalian morphological classes, storing them in a compact and parsimonious format. When modeled neurons ar e distributed in three-dimensional and biologically plausible rules governi ng axonal navigation and connectivity are added to the simulations, entire portions of the nervous system can be "grown" as anatomically realistic neu ral networks. These computational constructs are useful to determine the in fluence of local geometry on system neuroanatomy, and to investigate system atically the mutual interactions between anatomical parameters and electrop hysiological activity at the network level. A detailed computer model of a "virtual brain" that was truly equivalent to-the biological structure could in principle allow scientists to carry out experiments that could not be p erformed on real nervous systems because of physical constraints. The compu tational approach to neuroanatomy is just at its beginning, but has a great potential to enhance the intuition of investigators and to aid neuroscienc e education. Anat Rec (New Anat): 257:195-207, 1999. (C) 1999 Wiley-Liss, I nc.