Recent, cognitively based neuropsychological studies have established that retrograde amnesia is not a single entity. Profound loss of autobiographical memory, with relative sparing of knowledge of word meaning, facts about other people and personal semantic information, may arise from either disruption of thematic retrieval frameworks or a loss of individual memory traces. The opposite pattern of profound loss of general semantic information with preservation of autobiographical memory also occurs. Finer-grained loss of semantic information, involving famous persons or other categories have also been described, providing important clues regarding the representation and organization of such knowledge.