Two hallmarks of proper scientific language are precision and clarity. While precision requires that scientific terms define accurately what they mean, clarity is achieved only if, in a given context, each term can be applied exclusively to one object or phenomenon. Here we propose a systematic nomenclature for the neural projections established among structures of the mammalian midbrain tectum, a region of the central nervous system that suffers from considerable terminological confusion.
Traditionally, nerve fiber tracts in the central nervous system are named according to their site of origin and their place of destination. For example, corticospinal fibers are those that originate in the cerebral cortex and end in the spinal cord, just as the olivocochlear bundle arises from parent cell bodies located in the superior olive and carries axons to the cochlea. Accordingly, axons that originate in the tectum and end in the tectum are, by definition, tectotectal, and tectotectal neurons are tectal neurons that innervate other tectal neurons. Indeed, the adjective tectotectal has been widely used in the neuroanatomical literature. It is our contention, however, that the term tectotectal, which is technically correct, is often scientifically ambiguous, because, as discussed below, tectotectal projections are numerous and varied.