Neural Correlates of Body Integrity Dysphoria

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 [5-7], 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

Gaze, behavioral, and clinical data for phantom limbs after hand amputation from 15 amputees and 29 controls

Despite recent advances in prosthetics, many upper limb amputees still use prostheses with some reluctance. They often do not feel able to incorporate the artificial hand into their bodily self. Furthermore, prosthesis fitting is not usually tailored to accommodate the characteristics of an individual's phantom limb sensations. These are experienced by almost all persons with an acquired amputation and comprise the motor and postural properties of the lost limb. This article presents and validates a multimodal dataset including an extensive qualitative and quantitative assessment of phantom limb sensations in 15 transradial amputees, surface electromyography and accelerometry data of the forearm, and measurements of gaze behavior during exercises requiring pointing or repositioning of the forearm and the phantom hand. The data also include acquisitions from 29 able-bodied participants, matched for gender and age. Special emphasis was given to tracking the visuo-motor coupling between eye-hand/eye-phantom during these exercises

Brain Abnormalities in Individuals with a Desire for a Healthy Limb Amputation: Somatosensory, Motoric or Both? A Task-Based fMRI Verdict

Body integrity dysphoria (BID), a long-lasting desire for the amputation of physically healthy limbs, is associated with reduced fMRI resting-state functional connectivity of somatosensory cortices. Here, we used fMRI to evaluate whether these findings could be replicated and expanded using a task-based paradigm. We measured brain activations during somatosensory stimulation and motor tasks for each of the four limbs in ten individuals with a life-long desire for the amputation of the left leg and fourteen controls. For the left leg, BID individuals had reduced brain activation in the right superior parietal lobule for somatosensory stimulation and in the right paracentral lobule for the motor task, areas where we previously found reduced resting-state functional connectivity. In addition, for somatosensory stimulation only, we found a robust reduction in activation of somatosensory areas SII bilaterally, mostly regardless of the stimulated body part. Areas SII were regions of convergent activations for signals from all four limbs in controls to a significantly greater extent than in subjects with BID. We conclude that BID is associated with altered integration of somatosensory and, to a lesser extent, motor signals, involving limb-specific cortical maps and brain regions where the first integration of body-related signals is achieved through convergence

Gaze, visual, myoelectric, and inertial data of grasps for intelligent prosthetics

A hand amputation is a highly disabling event, having severe physical and psychological repercussions on a person’s life. Despite extensive efforts devoted to restoring the missing functionality via dexterous myoelectric hand prostheses, natural and robust control usable in everyday life is still challenging. Novel techniques have been proposed to overcome the current limitations, among them the fusion of surface electromyography with other sources of contextual information. We present a dataset to investigate the inclusion of eye tracking and first person video to provide more stable intent recognition for prosthetic control. This multimodal dataset contains surface electromyography and accelerometry of the forearm, and gaze, first person video, and inertial measurements of the head recorded from 15 transradial amputees and 30 able-bodied subjects performing grasping tasks. Besides the intended application for upper-limb prosthetics, we also foresee uses for this dataset to study eye-hand coordination in the context of psychophysics, neuroscience, and assistive robotics

Gaze, visual, myoelectric, and inertial data of grasps for intelligent prosthetics

A hand amputation is a highly disabling event, having severe physical and psychological repercussions on a person’s life. Despite extensive efforts devoted to restoring the missing functionality via dexterous myoelectric hand prostheses, natural and robust control usable in everyday life is still challenging. Novel techniques have been proposed to overcome the current limitations, among them the fusion of surface electromyography with other sources of contextual information. We present a dataset to investigate the inclusion of eye tracking and first person video to provide more stable intent recognition for prosthetic control. This multimodal dataset contains surface electromyography and accelerometry of the forearm, and gaze, first person video, and inertial measurements of the head recorded from 15 transradial amputees and 30 able-bodied subjects performing grasping tasks. Besides the intended application for upper-limb prosthetics, we also foresee uses for this dataset to study eye-hand coordination in the context of psychophysics, neuroscience, and assistive robotics

Where in the Brain is "the Other's" Hand? Mapping Dysfunctional Neural Networks in Somatoparaphrenia

Somatoparaphrenia refers to the delusional belief, typically observed in right brain-damaged patients, that the contralesional limbs belong to someone else. Here, we aimed to uncover the neural activity associated with this productive, i.e. confabulatory, component in a patient, S.P.P., with a large right-sided lesion of both cortical and subcortical gray and white matter. He claimed that his left paralyzed hand belonged to his mother. In a block-design functional magnetic resonance (fMRI) experiment, S.P.P. imagined that the mother would move her (i.e. his left) hand (condition "mother"). Subtraction of the activity elicited by control conditions (imagery of self-generated movement of either left or right hand) from that in the "mother" condition resulted in the focal activation of the pars opercularis of the right inferior frontal gyrus (rIFG). In a separate, resting-state fMRI experiment with S.P.P. and 21 healthy controls, we examined the functional connectivity of the rIFG and the affected hand somatosensory network to the rest of the brain. We found a negative correlation between the activity in the rIFG and that of Broca area and the temporo-parietal junction in the left hemisphere. Furthermore, the affected hand somatosensory network was disconnected from the left secondary somatosensory cortex. Our results link the productive component of somatoparaphrenia to the activity of crucial hubs for integrating the multimodal signals of the affected hand. Furthermore, they provide the first direct evidence supporting the "left narrator model", proposed by Halligan et al. (1995), according to which the confabulations of somatoparaphrenia are due to a disconnection of left hemisphere language areas from right hemisphere parieto-temporal cortex

Machine Learning to Predict Aerodynamic Stall

A convolutional autoencoder is trained using a database of airfoil aerodynamic simulations and assessed in terms of overall accuracy and interpretability. The goal is to predict the stall and to investigate the ability of the autoencoder to distinguish between the linear and non-linear response of the airfoil pressure distribution to changes in the angle of attack. After a sensitivity analysis on the learning infrastructure, we investigate the latent space identified by the autoencoder targeting extreme compression rates, i.e. very low-dimensional reconstructions. We also propose a strategy to use the decoder to generate new synthetic airfoil geometries and aerodynamic solutions by interpolation and extrapolation in the latent representation learned by the autoencoder.Comment: 15 pages, 22 figure