Aphasia
Aphasia (Greek a, “not”; phanai, “to speak”), term introduced by the French physician Armand Trousseau to denote inability to express thought by means of speech, as a consequence of certain brain disorders. The meaning has since been extended to cover loss of the faculty of interchanging thought, so that it may even denote a temporary but complete loss of memory . Motor aphasia involves a loss of memory of the coordinated movements necessary for the formation of symbols. This usually includes gestures, speech, and writing. (The inability to write is commonly termed agraphia.) Victims of this disorder are unable to name any object shown to them, although they know what it is. Neither can they reply to any question although they may understand it. In sensory aphasia, a loss of memory of the meaning of symbols occurs. This may affect the recollection of spoken language. The victim can hear every sound but cannot understand a single spoken word.