Date: Mon, 27 May 2002 09:43:14 +0200 (MEST) X-Sender: To: "List for Toru Shimizu" <> From: Loreta Medina Hernandez <> Subject: Re: Medina and Puelles proposal

Dear Erich and all,

I would like to add the following clarifications:

The term hodology (or hodological) refers to connections between brain structures.

The term topology refers to relative position of structures within the brain Bauplan. This is of course related to the developmental story and to specific cascades of developmental regulatory genes. One interesting aspect of the topology concept is that, within the Bauplan, each brain structure has a particular set of topological coordenates (within the longitudinal and dorsoventral axis), and a specific relationship to neighbour structures. These topological coordenates (and neighbour relationships) are conserved across vertebrates sharing a common brain Bauplan, independent of the different degree of growth (and deformation) of the structure in the various species. Homologous structures in two species should have exactly the same coordenates within the Bauplan (and the same relationships to neighbours).

Best wishes,