  Anatomical connectivity imposes strong constraints on brain function, but
there is no general agreement about principles that govern its organization.
Based on extensive quantitative data we tested the power of three models to
predict connections of the primate cerebral cortex: architectonic similarity
(structural model), spatial proximity (distance model) and thickness similarity
(thickness model). Architectonic similarity showed the strongest and most
consistent influence on connection features. This parameter was strongly
associated with the presence or absence of inter-areal connections and when
integrated with spatial distance, the model allowed predicting the existence of
projections with very high accuracy. Moreover, architectonic similarity was
strongly related to the laminar pattern of projections origins, and the
absolute number of cortical connections of an area. By contrast, cortical
thickness similarity and distance were not systematically related to connection
features. These findings suggest that cortical architecture provides a general
organizing principle for connections in the primate brain.
