From 2020... There are few things as irrefutable as the evidence that our limbs belong to us, but persons with body integrity dysphoria deny the ownership of one of their fully functional limbs and seek its amputation

From 2020... Neural Correlates of Body Integrity Dysphoria. Gianluca Saetta et al. Current Biology, May 07, 2020. https://doi.org/10.1016/j.cub.2020.04.001

Highlights

• Target limb sensorimotor area shows a breakdown of the functional connectivity

• Left premotor cortex typically involved in limb multimodal integration is atrophic

• Right parietal area representing body shape is structurally and functionally altered

• Atrophy in this right parietal area correlates with simulation of being an amputee

Summary: There are few things as irrefutable as the evidence that our limbs belong to us. However, persons with body integrity dysphoria (BID) [1] deny the ownership of one of their fully functional limbs and seek its amputation [2]. We tapped into the brain mechanisms of BID, examining sixteen men desiring the removal of the left healthy leg. The primary sensorimotor area of the to-be-removed leg and the core area of the conscious representation of body size and shape (the right superior parietal lobule [rSPL]) [3, 4] were less functionally connected to the rest of the brain. Furthermore, the left premotor cortex, reportedly involved in the multisensory integration of limb information [5, 6, 7], and the rSPL were atrophic. The more atrophic the rSPL, the stronger the desire for amputation, and the more an individual pretended to be an amputee by using wheelchairs or crutches to solve the mismatch between the desired and actual body. Our findings illustrate the pivotal role of the connectivity of the primary sensorimotor limb area in the mediation of the feeling of body ownership. They also delineate the morphometric and functional alterations in areas of higher-order body representation possibly responsible for the dissatisfaction with a standard body configuration. The neural correlates of BID may foster the understanding of other neuropsychiatric disorders involving the bodily self. Ultimately, they may help us understand what most of us take for granted, i.e., the experience of body and self as a seamless unity.