Partial correspondence ( Swanson & Bota, 2010 ) : In neuroanatomy many terms do not fit exactly into any part of the structural hierarchy. Such terms partly correspond to a standard term somewhere in the hierarchy, and should be defined (described) with reference to the immediately higher standard term within which it completely fits. The concept of a partly corresponding term is important because such a term generally does not share all of the properties of any particular reference term and thus cannot fit exactly anywhere within the hierarchy as such-it does not have a strict PART-OF relationship with any component of the Foundational Model of Connectivity hierarchy. This is because gray matter regions and neuron types (Bota & Swanson, 2007) generally are not homogeneous; instead, they have defining and differentiable features in parameter space that occur in gradients. As a result different sites within a gray matter region generally have different features and thus different microconnections.