Aphasia research and cerebral localisation of language processes

Aphasia research has become an acknowledged branch of modern cognitive neur opsychology research whose aim is to explore more fully the structures of k nowledge and of cerebral processes which might both be affected in patients with aphasia. Up to the second half of this century, a model based on a specific cerebral localisation of language processes had emerged based on brain localisation research by Broca and Wernicke (among others). New modern neuroimaging tec hniques, however, such as computed tomography and magnetic resonance imagin g (ICIRI), but also functional imaging modalities such as positron emission tomography or functional MRI, have modified these concepts. It emerges tha t in comprehension as well as in production of language, not only a few wel l defined centres are responsible for the activity, but there is a synchron ised activity in large neuronal networks connecting various regions located both in the cortex and in the deep subcortical structures; today, this act ivity can be demonstrated best in a non-invasive MRI.