Neural homologies: Principles, databases and modeling

The concept of homology is central for understanding biological structures at different levels of organization. The problem of establishing homologies of structures of the central nervous system is particularly important for explanation of the internal structures and functionality of brain nuclei of interest from different species. The identification of neural homologies across species is problematic, since it involves the evaluation of a set of criteria considered to have specific weights by different schools of comparative neurobiology. The process of establishing homologies at the neural level should also address the problem of heterogeneity of the neurobiological information provided by different sources.; We propose here a theoretical framework for evaluation of the homologies at the neural level. Central to this, is the concept of degree of homology (DG), proposed as an overall measure of close brain structures from different species are. The evaluation of the degree of homology depends on the structural and functional criteria that are used to compare brain structures from different species.; In order to support the computation of DG as reflected from the literature, we have developed two knowledge management systems (KMS) which allow the users to evaluate it online from the inserted data. The KMS can be used both as summary databases for neurobiological information and as expert systems for evaluation of the neurobiological information as reflected in the literature.; Furthermore, the developed KMS allow users to evaluate the neuroanatomical connections from data collated from the literature, infer the qualitative spatial relationships between cortical structures in different neuroanatomical atlases of a given species and translate the connectivity information revealed in a atlas to other parcellation schemes.; The structures of the online KMS allow the insertion of information specific to different levels of organization of the nervous system and permit users to create personal accounts, insert and share personal data with other users inside of different groups.; In this way, we not only provide a theoretical framework for the objective evaluation of similarities between brain structures, but also online KMS for systematization and sharing of the neurobiological information.