With National Science Foundation support, Drs. Eckert and Binder and colleagues will conduct a two-year investigation of the brain specialization for language. Most people are dependent on brain areas in the left hemisphere to process language. Only rarely is the right hemisphere essential for understanding or producing language. The reasons for this left-hemisphere language dominance remain unexplained. One popular explanation suggests that larger left hemisphere language-related areas, compared to the right hemisphere, predispose language to organize in the left hemisphere. Superior verbal ability may stem from this structural and functional organization. The present research project tests this explanation for language organization, as well as an alternative explanation that proposes that left hemisphere language-related areas are not the basis for language dominance, but interact with language dominance to predict verbal ability. Functional Magnetic Resonance Imaging and the intracarotid anesthetization procedure will be used to assess language laterality in normal (functional imaging only) and epilepsy subjects. Anatomical data will be collected from MRI scans. This study will be the first to directly test hypotheses about the relation between language, anatomical asymmetries, and cognition. In addition, this study will increase understanding of functional imaging results by examining how individual variation in neuroanatomy influences individual variability in functional imaging patterns of activation.
