Behavioral neurology in language and aphasia: from basic studies to clinical applications.

With increasing aging population, cognitive deteriorations due to neuro- degenerative diseases or stroke are so commonly observed that it is thought to be inevitable with aging. For dementia and stroke, a communication disorder due to language deterioration is one of the main problems. Behavioral neurology aims to clarify the relationship between brain function and behavior; language deterioration is one of the main targets, and its clinical applications are really useful for making better understanding of patients.