Article

Conspicuous deficits in face recognition characterize prosopagnosia. Information
on whether agnosic deficits may extend to non-facial body parts is lacking. Here
we report the neuropsychological description of FM, a patient affected by a
complete deficit in face recognition in the presence of mild clinical signs of
visual object agnosia. His deficit involves both overt and covert recognition of
faces (i.e. recognition of familiar faces, but also categorization of faces for
gender or age) as well as the visual mental imagery of faces. By means of a
series of matching-to-sample tasks we investigated: (i) a possible association
between prosopagnosia and disorders in visual body perception; (ii) the effect of
the emotional content of stimuli on the visual discrimination of faces, bodies
and objects; (iii) the existence of a dissociation between identity recognition
and the emotional discrimination of faces and bodies. Our results document, for
the first time, the co-occurrence of body agnosia, i.e. the visual inability to
discriminate body forms and body actions, and prosopagnosia. Moreover, the
results show better performance in the discrimination of emotional face and body
expressions with respect to body identity and neutral actions. Since FM's lesions
involve bilateral fusiform areas, it is unlikely that the amygdala-temporal
projections explain the relative sparing of emotion discrimination performance.
Indeed, the emotional content of the stimuli did not improve the discrimination
of their identity. The results hint at the existence of two segregated brain
networks involved in identity and emotional discrimination that are at least
partially shared by face and body processing.
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Langue : ANGLAIS