Ryuta Kawashima
NICHe, Tohoku University, Sendai, Japan

Abstract; The recent advancement of functional brain imaging techniques enable us to visualize cognitive processes in the human brain. In this talk, functional organization of the human brain involved in language processing will be discussed from the results of series of our functional imaging studies. We investigated brain activation in relation to input and output of auditory language as well as these of written language using positron emission topography or functional magnetic resonance imaging. Although, the results of the most of these studies support a classical model of Dejerine (1914), we found new functional roles in language processing of the prefrontal cortex. One of the most striking findings from the summary of our studies combined with previous human brain mapping investigations is that there exist at least two functionally distinct modules involved in semantic operations in the inferior frontal cortex of the left hemisphere. Namely, the anterior module subserves semantic processing and the posterior module subserves phonological processing. It is also interesting to note that these modules are involved in syntactic processing as well as visual imagination.