Aphasia: progress in the last quarter of a century.

In the last 25 years, characterization of aphasia has shifted from descriptions of the language tasks that are impaired by brain damage to identification of the disrupted cognitive processes underlying language. At the same time advances in technology, including functional imaging, electrophysiologic studies, perfusion imaging, diffusion tensor imaging, and transcranial magnetic stimulation, have led to new insights regarding the relationships between language and the brain. These insights, together with computational models of language processes, converge on the view that a given language task relies on a complex set of cognitive processes and representations carried out by an intricate network of neural regions working together. Recovery from aphasia depends on restoration of tissue function or reorganization of the cognitive/neural network underlying language, which can be facilitated by a number of diverse interventions. The original research by the author reported in this article was supported by NIH R01 DC05375.