Neural Substrates of Semantics: John Hart, Jr., Lauren R. Moo, Jessica B. Segal, Ellen Adkins, and Michael A. Kraut
Delineating the neural bases of semantics, even for single entities (objects, features of objects, categories, actions, and so on) has been fraught with numerous difficulties, including variable definitions of semantic terms and several different models of the functional organization of semantics (see Elaine Funnell, chapter 10 of this book). In addition, while the advent of new investigative techniques has been a major asset in detecting brain regions associated with semantics, this variety of investigative techniques and their frequently incongruent results have confused, perhaps as often as clarified, previous experimental findings. For example, the results of activation studies (PET, fMRI, ERP, and so on), which demonstrate regions "involved" in performing a task, have yet to be fully integrated with the results of lesion-based studies that show regions "essential" for performing a task. A complete account of the complex mechanisms involved in semantics will almost certainly be predicated on the results of such an integration.