Shigeru Miyagawa proposes that syntax extends into the domain of discourse by making linkages between core syntax and the conversational participants. Miyagawa draws on evidence for this extended syntactic structure from a wide variety of languages, including Basque, Japanese, Italian, Magahi, Newari, Romanian, and Spanish, as well as the language of children with autism. His proposal for what happens at the highest level of the tree structure used by linguists to represent the hierarchical relationships within sentences - "in the treetops" - offers a unique contribution to the new area of study sometimes known as "syntacticization of discourse."