Computerized tomographic procedures have been used extensively since their introduction to examine specific language disabilities in aphasic patients and to correlate anatomical and clinical changes. The resulting overwhelming evidence in favour of lateralisation and localisation has been confirmed by regional blood flow studies and punctate electrical stimulation as well as by the topographic maps provided by neurometries. That specific lexical functions are localised within the peri-Sylvian cortex in the left cerebral hemisphere is now generally accepted, but the macroscopic mapping, which largely ignores the contribution of the ipsilateral thalamus and possibly of the basal nuclei, must not be mistaken for the language encoding processes in the parallel pathways which have been identified.
