Heterotopagnosia

Heterotopagnosia-without-Autotopagnosia (HwA) is characterized by the incapacity to point to body parts on others, but not on one's own body. This has been classically interpreted as related to a self-other distinction, with impaired visual representations of other bodies seen in third person perspective (3PP), besides spared own body somatosensory representations in 1PP. However, HwA could be impacted by a deficit in the integration of visual and somatosensory information in space, that are spatially congruent in the case of one's own body, but not for others' body...

Pointing is a communicative gesture that allows individuals to share information about surrounding objects with other humans. Patients with heterotopagnosia are specifically impaired in pointing to other humans' body parts but not in pointing to themselves or to objects. Here, we describe a female patient with heterotopagnosia who was more accurate in pointing to men's body parts than to women's body parts. We replicated this gender effect in healthy participants with faster reaction times for pointing to men's body parts than to women's body parts...

Humans usually point at objects to communicate with other persons, although they generally avoid pointing at the other's body. Moreover, patients with heterotopagnosia after left parietal damage cannot point at another person's body parts, although they can point at objects and at their own body parts and although they can grasp the others' body parts. Strikingly, their performance gradually improves for figurative human body targets. Altogether, this suggests that the body of another real person holds a specific status in communicative pointing...

We studied the involvement of the parietal cortex in interpersonal body representation in a left parietal stroke patient. We used tasks assessing different types of body representations and localization of object parts. The patient performed normally on all tasks of body knowledge. However, she was unable to locate body parts on another person or on body representations. In contrast, she pointed correctly to the same body parts on herself or object representations. The data support the important role of the left parietal cortex in the transformation of intrinsic spatial coding of body parts localization in extrinsic body part coordinates...

Heterotopagnosia is the acquired inability of brain-lesioned patients to point at someone else's body parts when prompted. The cognitive basis of this disorder is unclear. It might result from a biological function deficit critical for communication in human beings; alternatively, it could result from the disruption of a body representation. Here, we report three patients with heterotopagnosia following a recent left parieto-occipital stroke and a previous insular lesion. The patients were tested on their ability to name, point out and grasp several targets including body parts (own, real others' and figurative others')...

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...