Primary progressive aphasia (PPA) is an acquired neurodegenerative syndrome that has specific and devastating effects on an individual's speech and language ability. Based on a detailed assessment of behavior and cognition, combined with structural neuroimaging data and pathological evidence, PPA is typically classified into three variants: the…

Fifteen years ago, Pascual-Leone and colleagues used transcranial magnetic stimulation (TMS) to investigate speech production in pre-surgical epilepsy patients and in doing so, introduced a novel tool into language research. TMS can be used to non-invasively stimulate a specific cortical region and transiently disrupt information processing. These…

Develops the distinction between "referential" and "modalizing" aspects of language and describes their functional dissociation, as observed in various manifestations of aphasia and in the speech of hemispherectomy and commissurotomy patients. (Author/JL)