[Pointing and its object: towards the neuropsychology of objectivation]

We describe a disorder similar to body-image agnosia or autotopagnosia characterized by the inability to designate targets situated outside the body. This disorder, which we have termed allotopagnosia, occurs exclusively in subjects with a lesion involving the posterior region of the left parietal lobe. The most common manifestation is the designation of parts of the body of another person as being part of the patient's own body (heterotopagnosia with self-designation). This disorder cannot be explained by aphasia, apraxia, or visuomotor dysfunction nor by an inability to identify parts of the body as self. Patient's expression of the confusion between their own body with that of others and the gestures they use to designate indicate a relationship with reality (non-self and target) confined to the human species. The disorder appears in children at the same time as language acquisition. This suggests the hypothesis that allotopagnosia results from a deficit or dysfunction of the left parietal lobe where outside elements are attributed to situations and identities independent of self.