The contribution of positron emission tomography to the study of aphasia

Positron emission tomography (PET) with perfusion and metabolism tracers, the first functional brain imaging method extensively applied to the study of the brain correlates of human cognitive function, has played a central role in the study of aphasia due to stroke. By showing the extent of intra-hemispheric and interhemispheric remote effects associated with focal damage and the reorganization of language networks during aphasia recovery, it has substantially contributed to the in vivo investigation of plasticity effects. Nowadays the main area of application of PET methods, including the new, powerful molecular imaging approaches using tracers binding to target biological receptors, is aphasia due to neurodegenerative disorders, and in particular the syndromes of primary progressive aphasia. In this extremely active research field, PET imaging is contributing to clinical diagnosis, correlation studies of specific aspects of linguistic impairment, and the in vivo exploration of the underlying pathologic processes.