Beyond re-membering: Phantom sensations of congenitally absent limbs

Citation
P. Brugger et al., Beyond re-membering: Phantom sensations of congenitally absent limbs, P NAS US, 97(11), 2000, pp. 6167-6172
Citations number
41
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
ISSN journal
00278424 → ACNP
Volume
97
Issue
11
Year of publication
2000
Pages
6167 - 6172
Database
ISI
SICI code
0027-8424(20000523)97:11<6167:BRPSOC>2.0.ZU;2-1
Abstract
Phantom limbs are traditionally conceptualized as the phenomenal persistenc e of a body part after deafferentation, Previous clinical observations of s ubjects with phantoms of congenitally absent limbs are not compatible with this view, but, in the absence of experimental work, the neural basis of su ch "aplasic phantoms" has remained enigmatic. In this paper, we report a se ries of behavioral, imaging, and neurophysiological experiments with a univ ersity-educated woman born without forearms and legs, who experiences vivid phantom sensations of all four limbs. Visuokinesthetic integration of tach istoscopically presented drawings of hands and feet indicated an intact som atic representation of these body parts. Functional magnetic resonance imag ing of phantom hand movements showed no activation of primary sensorimotor areas, but of premotor and parietal cortex bilaterally. Movements of the ex isting upper arms produced activation expanding into the hand territories d eprived of afferences and efferences, Transcranial magnetic stimulation of the sensorimotor cortex consistently elicited phantom sensations in the con tralateral fingers and hand. In addition, premotor and parietal stimulation evoked similar phantom sensations, albeit in the absence of motor evoked p otentials in the stump. These data indicate that body parts that have never been physically developed can be represented in sensory and motor cortical areas. Both genetic and epigenetic factors, such as the habitual observati on of other people moving their limbs, may contribute to the conscious expe rience of aplasic phantoms.