Body ownership: When feeling and knowing diverge.

Area of Science:

• Neuroscience
• Psychiatry
• Body Integrity Identity Disorder (BIID)

Background:

• Body Integrity Identity Disorder (BIID) involves an intense desire to amputate a healthy limb, accompanied by a sense of disownership.
• BIID shares similarities with somatoparaphrenia, a delusion where individuals disown their own limb.
• Understanding the sensory processing in BIID can offer insights into body ownership and related neurological conditions.

Purpose of the Study:

• To investigate the anticipatory physiological responses to noxious stimuli in individuals with BIID.
• To compare the responses of individuals with BIID to those previously observed in somatoparaphrenia patients.
• To determine if altered threat anticipation in BIID is linked to the sense of limb ownership.

Main Methods:

• Skin conductance response (SCR) was measured in ten individuals with BIID.
• Noxious stimuli were delivered to both accepted and non-accepted limbs, including direct contact and simulated approach.
• SCR was analyzed for anticipatory responses to tactile and non-tactile stimuli near the limbs.

Main Results:

• Individuals with BIID exhibited reduced anticipatory SCR to stimuli approaching, but not contacting, their non-preferred limb.
• Conversely, direct contact with the non-accepted limb elicited a stronger SCR compared to the accepted limb.
• These findings indicate a differential processing of threat based on the limb's perceived ownership.

Conclusions:

• The study suggests that the sense of limb ownership is critical for the appropriate processing of incoming threats.
• Altered threat anticipation in BIID, particularly to approaching stimuli, highlights the role of body ownership in sensory perception.
• Findings support the hypothesis that BIID patients exhibit similar altered sensory processing to somatoparaphrenic patients regarding disowned limbs.