The high level model forms a large, structured, body of knowledge describing the anatomy of the human brain. The knowledge was acquired through three channels. The first was documented discussion with a neurologist which aided in deciding what were the important anatomical features that needed to be modelled. The second was the use of anatomical text books and neuroanatomical atlases. Most of the knowledge was acquired from text books and atlases, especially Nieuwenhuys et al. [18] which provided description of the function and relationships between anatomical features, and Talairach et al. [19] which provided three dimensional information about the structures. The shape descriptions described later in this paper were derived from the Talairach atlas. The third was informal discussion with neurologists and neuro-radiologists. This allowed any anomalies in the representation of the anatomy of the brain to be resolved.