Bilateral Language and Commissurotomy

Abstract

Although the behavioral study of commissurotomy patients has focused almost exclusively on questions about the functional differences between the disconnected hemispheres, the surgical procedure has also provided an opportunity to study a wide range of interactions between the hemispheres that have significant effects on behavior (e.g., see Holtzman, this volume, Chapter 19). With the development of the staged surgical technique (see Roberts, this volume, Chapter 11) it not only has become possible to study interhemispheric interaction with and without a corpus callosum, but also to study interactions that occur with only the anterior or posterior half of the callosum intact. Behavioral examinations of patients during pre-, inter-, and postoperative periods have provided new insights into sensory and motor interhemispheric interaction (see Volpe, this volume, Chapter 21), as well as a first glimpse of how the two hemispheres can interact on a cognitive level in the absence of direct sensory or perceptual information (Sidtis et al., 1981a). This chapter will focus on cognitive interactions between the hemispheres by describing some of the recent work on semantic information processing carried out with commissurotomy patients who have some bilateral language capacity.