Slowly progressive defect in recognition of familiar people in a patient with right anterior temporal atrophy

We report the case of a patient (C.O.) who showed a selective defect in the recognition of familiar people, with very mild disease progression during a period of 30 months resulting from focal atrophy of the right temporal lobe. On formal neuropsychological testing, C.O. obtained high scores on tests of general intelligence, episodic memory, language, executive functions, selective attention, visual recognition and visual-spatial abilities. On more specific tasks of familiar and unfamiliar face recognition, C.O. scored above the controls' means on perceptual tests, but obtained highly pathological results on mnesic-associative tests. His disorder of recognition of familiar people was not due to loss of person-specific information, since he obtained highly abnormal naming scores when presented with photographs of famous people but borderline or mildly abnormal scores in a tasks in which he had to name celebrities from verbal definitions. On the other hand, C.O.'s recognition disorder could not be considered to be a form of 'associative prosopagnosia' since a similar defect was observed when he was requested to access information about famous persons through their voice rather than their face. Two alternative interpretations are advanced to explain C.O.'s inability to access his relatively spared person-specific knowledge not only through the person's face but also through the person's voice. The first hypothesis is that, before accessing the person-specific information, unimodal recognition channels must converge into a multimodal, non-verbal person-recognition system and that the right anterior temporal cortices play a crucial role in this integrative activity. The second hypothesis is that the face-recognition units have privileged access to person-specific semantic knowledge and that other recognition subsystems require coactivation of the face-recognition units in order to access person-specific semantic information.