Spatial perspective and coordinate systems in autoscopy: a case report of a "fantome de profil" in occipital brain damage.
Autoscopic phenomena refer to complex experiences involving the illusory reduplication of one's own body. Here we report the third long-lasting case of autoscopy in a patient with right occipital lesion. Instead of the commonly reported frontal mirror view (fantôme spéculaire), the patient saw her head and upper trunk laterally in side view (fantôme de profil). We found that the visual appearance and completeness of the autoscopic image could be selectively modulated by active and passive movements, without being influenced by imagining the same movements or by tactile and auditory stimulation. Eyes closure did not disrupt either the perception of the autoscopic body or the effects of the motor stimulation. Moreover, the visual body reduplication was coded neither in purely eye-centered nor in head-centered frames of reference, suggesting the involvement of egocentric coordinate systems (eyes and head centered). A follow-up examination highlighted the stability of the visual characteristics of the body reduplication and its shift induced by displacement of both head and eyes. These findings support the view that autoscopic phenomena have a multisensory motor origin and proprioceptive signals may play an important role in modulating the illusory visual reduplication of the patient's own body, most likely via cross-modal modulation of extrastriate areas involved in body and face perception.
Bolognini
Nadia
N
Università di Bologna, Italy.
Làdavas
Elisabetta
E
Farnè
Alessandro
A
D057215:Body Dysmorphic Disorders / Q000473:pathology / Q000503:physiopathology*; D001932:Brain Neoplasms / Q000601:surgery; D005260:Female; D006212:Hallucinations / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009778:Occipital Lobe / Q000473:pathology / Q000503:physiopathology*; D010469:Perceptual Distortion / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011183:Postoperative Complications / Q000473:pathology / Q000503:physiopathology; D013028:Space Perception / Q000502:physiology*