FUNCTIONAL NEUROANATOMY OF LANGUAGE EXPLORED WITH POSITRON EMISSION TOMOGRAPHY

Recent advances in positron emission tomography provide a way of studying the functional anatomy of language processes in the normal brain. A large amount of data has already been acquired using the subtractive activation method which consists of comparing regional metabolic brain activities between two experimental conditions, a reference condition and an active condition (including a language task). The interpretation of such results may be obscured by various methodological problems as well as conflicting theoretical issues on the nature of brain-language relationships. The exact nature of the language task and stimuli used in the activation paradigms appear to be critical for this topic. Moreover, the strictly hierarchical subtractive method (previously described by Petersen et al, [2].) is not adequate to generate appropriate contrasts between activation conditions in most language paradigms. Further progress are expected from the inter-regional correlational analysis of cerebral activities which could account for the distributed anatomy of language functions, as well as from single subject studies in which issues on anatomical and cognitive inter-individual variability may be addressed.