Crossmodal agnosia for familiar people as a consequence of right infero-polar temporal atrophy

A 60-year-old, right-handed woman, with no focal brain lesions, suffered fr om a progressive impairment in recognising people of personal relevance and public figures familiar to her in the premorbid period. The patient did no t suffer from general cognitive deterioration. There was no ecological or c lear psychometric evidence of visuoperceptual or visuospatial deficits. Her defective person recognition was not overcome by extra-facial (e.g., obser ving animated people in their usual surroundings) or extra-visual informati on (e.g., listening to the voice). Moreover, presenting the correct name in the presence of an unrecognised familiar person failed to prompt her famil iarity judgement, or retrieval of the relevant biographical knowledge. The patient also had some recognition difficulties with famous buildings and so ngs as well as with some common objects. It is argued that the patient's difficulty in identifying familiar people w as the consequence of progressive loss of stored exemplars of familiar pers ons and perhaps also of some other "unique items" (famous songs and monumen ts) in an independent subsystem of semantics that we term "exemplar semanti cs." We discuss the associative (semantic) nature and specificity of the de ficit in person knowledge, the possible top-down negative influences of the loss of exemplars in the person recognition system, and the link between t he disorders and the right/left temporal lobe.