[Body, mind and culture : The complex dimensions of experiencing pain]

This article deals with the interrelationship between body, mind and culture with respect to being healthy and being ill. If one wants to treat not only sickness but also sick people, it is helpful to be aware not only of the somatic and psychological dimensions of a disease but also of the "cultural" dimension of a disease. Based on personal reflections and supplemented by a focused literature search this article provides insights into how cultural influences not only affect the experience of illness but also decide how an illness is dealt with individually and socially. Furthermore, it is shown that not only being sick but also the sick body can be understood in somatic, psychological and cultural dimensions and that a distinction must be made between the body as it physically is and as it is subjectively perceived. Finally, an insight into the complexity of the somatopsychic and psychosomatic interactions is provided in order to derivatively show how mental stress can lead to physical pain and physical pain can become a mental stressor.

Have I Been Touched? Subjective and Objective Aspects of Tactile Awareness

Somatosensory tactile experience is a key aspect of our interaction with the environment. It is involved in object manipulation, in the planning and control of actions and, in its affective components, in the relationships with other individuals. It is also a foundational component of body awareness. An intriguing aspect of sensory perception in general and tactile perception in particular is the way in which stimulation comes to consciousness. Indeed, although being aware of something seems a rather self-evident and monolithic aspect of our mental states, sensory awareness may be in fact modulated by many different processes that impact on the mere stimulation of the skin, including the way in which we perceive our bodies as belonging to us. In this review, we first took into consideration the pathological conditions of absence of phenomenal experience of touch, in the presence of implicit processing, as initial models for understanding the neural bases of conscious tactile experience. Subsequently, we discussed cases of tactile illusions both in normal subjects and in brain-damaged patients which help to understand which high-order processes impact tactile awareness. Finally, we discussed the observations reported in the review in light of some influential models of touch and body representation.

Subcortical contributions to the sense of body ownership

The sense of body ownership (i.e. the feeling that our body or its parts belong to us) plays a key role in bodily self-consciousness and is believed to stem from multisensory integration. Experimental paradigms such as the rubber hand illusion have been developed to allow the controlled manipulation of body ownership in laboratory settings, providing effective tools for investigating malleability in the sense of body ownership and the boundaries that distinguish self from other. Neuroimaging studies of body ownership converge on the involvement of several cortical regions, including the premotor cortex and posterior parietal cortex. However, relatively less attention has been paid to subcortical structures that may also contribute to body ownership perception, such as the cerebellum and putamen. Here, on the basis of neuroimaging and neuropsychological observations, we provide an overview of relevant subcortical regions and consider their potential role in generating and maintaining a sense of ownership over the body. We also suggest novel avenues for future research targeting the role of subcortical regions in making sense of the body as our own.

A conceptual framework on body representations and their relevance for mental disorders

Many mental disorders are accompanied by distortions in the way the own body is perceived and represented (e.g., eating disorders, body dysmorphic disorder including muscle dysmorphia, or body integrity dysphoria). We are interested in the way these distortions develop and aim at better understanding their role in mental health across the lifespan. For this purpose, we first propose a conceptual framework of body representation that defines this construct and integrates different perspectives (e.g., cognitive neuroscience, clinical psychology) on body representations. The framework consists of a structural and a process model of body representation emphasizing different goals: the structural model aims to support researchers from different disciplines to structure results from studies and help collectively accumulate knowledge about body representations and their role in mental disorders. The process model is reflecting the dynamics during the information processing of body-related stimuli. It aims to serve as a motor for (experimental) study development on how distorted body representations emerge and might be changed. Second, we use this framework to review the normative development of body representations as well as the development of mental disorders that relate to body representations with the aim to further clarify the potential transdiagnostic role of body representations.

Interoceptive and Affective Alterations in Body Integrity Dysphoria: An Online Self-Reporting Study

INTRODUCTION

Body integrity dysphoria (BID) is a rare condition in which individuals experience a long-lasting desire to achieve a specific physical disability. In this study, we tested the hypothesis of interoceptive and affective abnormalities in BID, in line with the evidence of structural and functional alteration of the interoceptive-affective neural system in these individuals.

METHOD

Our study involved 68 participants with BID (mean age: 35.6, SD: 16.4). Among these participants, 47 expressed a desire for amputation, 14 desired paralysis, 3 sought sensory deprivation, and 3 desired a combination of these forms. For comparisons, we recruited a control group of 79 participants (mean age: 35.2, SD: 15.8). We administered assessment measures to investigate alexithymia level (TAS-20), disgust sensitivity (DS-R), interoceptive awareness (MAIA-2), and (affective and cognitive) empathy (QCAE). We also administered the Short Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) to identify psychiatric comorbidities. Subgroups with low O-LIFE scores (BID = 31; controls = 43) and subgroups with high O-LIFE scores (BID = 37; controls = 36) were derived through a median-split procedure.

RESULTS

Within the BID low O-LIFE group, we found reduced interoceptive sensibility, reduced disgust sensitivity, and increased difficulty in identifying feelings, which refers to a dimension of the alexithymia trait. Within the BID high O-LIFE group, we observed a reduced disgust sensitivity and interoceptive sensibility, accompanied by a diminished score in cognitive empathy.

CONCLUSION

Our study suggests that BID can be associated with altered interoceptive and affective processing.

Ownership of the affected leg is further reduced following deceptive behaviors in body integrity dysphoria

Although predicted by the notion of embodied morality, it remains unknown whether a reduced sense of body ownership (SoO) is associated with increased or decreased dishonesty. To clarify this issue, we tested patients with body integrity dysphoria (BID), a clinical condition characterized by chronic reductions of SoO toward one leg that patients persistently desire to have amputated. Participants with BID played a card game in which they could voluntarily tell the truth or cheat an opponent, and thus either steal or give them money. To assess whether SoO toward the effector limb influences (im)moral decisions, responses were communicated with the affected or the unaffected leg. We found that a higher number of self-gain lies was followed by further reductions of SoO toward the affected leg. Our result supports the idea that reductions of SoO may follow immoral behaviors to distance from unwanted characteristics of the self, like one's own dishonesty.

Influence of bodily states on cognition: A web-based study in individuals with body integrity dysphoria

There is a constant reciprocal flow of information between the malleable sensorimotor states of the body and cognitive functions, and some embodied cognition approaches argue that many cognitive-affective mechanisms depend on the physical characteristics of the body. To examine such influences of bodily state, the current study compared patients with body integrity dysphoria (BID) with an amputation desire of the lower limb to a healthy control group on an Implicit Association Test for self-identity and self-esteem, and a pain evaluation task. Patients with BID completed the tasks once while emulating their desired bodily state and once while simulating their undesired bodily state, while healthy controls were split into two groups: one control group completed the experiment once while either sitting on one leg and once while sitting in a normal position, whereas the other control group completed both experiments while sitting in a normal position. Results demonstrate that patients with BID implicitly identify more strongly with an amputated body, whereas healthy controls demonstrate stronger identification with a complete body, independent of bodily state. Furthermore, implicit self-esteem did not differ between the groups and was also not modulated by bodily state manipulation in any of the groups. Pain evaluation ratings were not influenced by bodily state manipulation, perspective, or consistency. Pain forced choice response times, however, revealed that individuals with BID were faster to judge whether the stimulus depicted was painful when simulating their desired bodily state. These results provide insightful information to how both the subjective sense of body, as well as more transient alterations of objective sensorimotor states of the physical body may exert selective pressure on certain cognitive tasks.

The Desirability of Difference: Georges Canguilhem and Body Integrity Identity Disorder

Opponents of the provision of therapeutic, healthy limb amputation in Body Integrity Identity Disorder cases argue that such surgeries stand in contrast to the goal of medical practice - that of health restoration and maintenance. This paper refutes such a conclusion via an appeal to the nuanced and reflective model of health proposed by Georges Canguilhem. The paper examines the conceptual entanglement of the statistically common with the normatively desirable, arguing that a healthy body can take multiple forms, including that of an amputee, provided that such a form enables the continuing ability to initiate new norms of existence. It concludes that the practice of healthy limb amputation in cases of Body Integrity Identity Disorder is not only compatible with the goal of medicine but is potentially the only method of achieving this goal in the face of a complex and often mischaracterized disorder.

An Algorithm for Elective Amputation Combined with Targeted Muscle Reinnervation in Complex Regional Pain Syndrome—A Perspective

Complex regional pain syndrome (CRPS) can result in a devastating condition. For a small number of patients, there is a non-response to any existing multimodal therapies and they ultimately request amputation. Such a drastic and final decision is not easy to take for both the patient and the surgeon and requires careful and interdisciplinary assessments and considerations. Furthermore, new surgical procedures, such as targeted muscle reinnervation (TMR) and hybrid prosthetic fitting, and multidisciplinary board advice should be included when considering amputation. In order to help other therapeutic teams in decision making for such rare but more than demanding cases, we aimed to propose an advanced algorithm for amputation indications in CRPS patients combining all these new factors. This algorithm consists of extensive pre-operative psychiatric assessment, diagnostic hybrid prosthetic fitting including fMRI analyses, multidisciplinary board advice as well as targeted muscle reinnervation and amputation procedures with final prosthetic fitting and rehabilitation. By involving multiple disciplines, this algorithm should provide optimized and individualized patient treatment on the one hand and a reliable base for decision making for therapists on the other.

Individual differences in the experience of body ownership are related to cortical thickness

The widely used rubber hand illusion (RHI) paradigm provides insight into how the brain manages conflicting multisensory information regarding bodily self-consciousness. Previous functional neuroimaging studies have revealed that the feeling of body ownership is linked to activity in the premotor cortex, the intraparietal areas, the occipitotemporal cortex, and the insula. The current study investigated whether the individual differences in the sensation of body ownership over a rubber hand, as measured by subjective report and the proprioceptive drift, are associated with structural brain differences in terms of cortical thickness in 67 healthy young adults. We found that individual differences measured by the subjective report of body ownership are associated with the cortical thickness in the somatosensory regions, the temporo-parietal junction, the intraparietal areas, and the occipitotemporal cortex, while the proprioceptive drift is linked to the premotor area and the anterior cingulate cortex. These results are in line with functional neuroimaging studies indicating that these areas are indeed involved in processes such as cognitive-affective perspective taking, visual processing of the body, and the experience of body ownership and bodily awareness. Consequently, these individual differences in the sensation of body ownership are pronounced in both functional and structural differences.

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.

Could Brain-Computer Interface Be a New Therapeutic Approach for Body Integrity Dysphoria?

Patients suffering from body integrity dysphoria (BID) desire to become disabled, arising from a mismatch between the desired body and the physical body. We focus here on the most common variant, characterized by the desire for amputation of a healthy limb. In most reported cases, amputation of the rejected limb entirely alleviates the distress of the condition and engenders substantial improvement in quality of life. Since BID can lead to life-long suffering, it is essential to identify an effective form of treatment that causes the least amount of alteration to the person's anatomical structure and functionality. Treatment methods involving medications, psychotherapy, and vestibular stimulation have proven largely ineffective. In this hypothesis article, we briefly discuss the characteristics, etiology, and current treatment options available for BID before highlighting the need for new, theory driven approaches. Drawing on recent findings relating to functional and structural brain correlates of BID, we introduce the idea of brain-computer interface (BCI)/neurofeedback approaches to target altered patterns of brain activity, promote re-ownership of the limb, and/or attenuate stress and negativity associated with the altered body representation.

Parietal Lobe Reorganization and Widespread Functional Connectivity Integration in Upper-Limb Amputees: A rs-fMRI Study

The right parietal lobe plays an important role in body image, and disorders of body image emerge after lesions in the parietal lobe or with parietal lobe epilepsy. Body image disorder also often accompanies upper-limb amputation, in which the patient misperceives that their missing limb is still part of their body. Cortical reorganization is known to occur after upper-limb amputation, but it is not clear how widespread and to what degree functional connectivity (FC) is reorganized post-amputation, nor whether such changes might be related to misperceptions of body image. Twenty-four subjects who had a traumatically upper-limb amputees (ULAs) and 24 age-matched healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans. Regions of interest (ROIs) in the right superior parietal gyrus (SPG_R) and right inferior parietal lobule (IPL_R) were defined using BrainNet Viewer. We calculated the amplitude of low-frequency fluctuations (ALFF) in ROIs and correlated the ROI mean amplitude of low-frequency fluctuations (mALFF) and mean scores on the phantom limb sensation (PLS) scale and beck depression index (BDI). We also calculated ROIs and whole-brain FC. Compared to the HC group, we observed significantly increased activation (mALFF) in ROIs of the ULA group. Moreover, correlation analyses revealed a significant positive correlation between ROI mALFF and scores on the PLS. There was a significant negative correlation between the SPG_R mALFF and BDI scores. Seed-based, whole-brain FC analysis revealed that FC in the ULA group significantly decreased in many brain regions across the entire brain. The right parietal lobe appears to be involved in some aspect of body awareness and depression in amputation patients. Upper-limb amputation results not only in reorganization in the local brain area formerly representing the missing limb, but also results in more widespread reorganization through FC changes in whole brain.

Predictors of Self-Reported Neglect-like Symptoms and Involuntary Movements in Complex Regional Pain Syndrome Compared to Other Chronic Limb Pain Conditions

Objective

In addition to pain, people with complex regional pain syndrome (CRPS) often report inattention to and disengagement from their affected limb (i.e., “neglect-like symptoms”). Understanding how these symptoms relate to other characteristics of CRPS, and chronic pain generally, could provide insights for preventing and treating CRPS.

Methods

We administered an online survey to people who received a diagnosis of CRPS (n = 335) and other chronic limb pain (n = 407). Neglect-like symptoms were assessed using the Neurobehavioral questionnaire.

Results

A principal component analysis identified two components: motor and cognitive neglect-like symptoms, and involuntary movements. Internal consistency of the components was acceptable. We conducted regression analyses with these as outcomes. Having CRPS, a painful lower limb, higher pain intensity, and somatic symptoms were associated with more motor and cognitive neglect-like symptoms. Having CRPS, higher pain intensity, depression, and somatic symptoms were associated with more involuntary movements. Age, gender, anxiety, disease duration, hours of pain per day, affected side, whether the limb was the most painful body part, and number of pain-related medical diagnoses were no predictors. Finally, motor and cognitive neglect-like symptoms were related to tremor; and involuntary movements to changes in skin color, swelling, sweating, toenails, weakness, and tremor.

Conclusions

This study confirms the specificity of inattention to and disengagement from the affected limb in CRPS, independent of other factors. Furthermore, two components of the Neurobehavioral questionnaire were disentangled: motor and cognitive neglect-like symptoms, and involuntary movements. Results could potentially help clinicians to better assess neglect-like symptoms in chronic pain .

Uncertainty Promotes Neuroreductionism: A Behavioral Online Study on Folk Psychological Causal Inference from Neuroimaging Data

INTRODUCTION

Increased efforts in neuroscience try to understand mental disorders as brain disorders. In the present study, we investigate how common a neuroreductionist inclination is among highly educated people. In particular, we shed light on implicit presuppositions of mental disorders little is known about in the public, exemplified here by the case of body integrity dysphoria (BID) that is considered a mental disorder for the first time in ICD-11.

METHODS

Identically graphed, simulated data of mind-brain correlations were shown in 3 contexts with presumably different presumptions about causality. 738 highly educated lay people rated plausibility of causality attribution from the brain to mind and from mind to the brain for correlations between brain structural properties and mental phenomena. We contrasted participants' plausibility ratings of causality in the contexts of commonly perceived brain lesion-induced behavior (aphasia), behavior-induced training effects (piano playing), and a newly described mental disorder (BID).

RESULTS

The findings reveal the expected context-dependent modulation of causality attributions in the contexts of aphasia and piano playing. Furthermore, we observed a significant tendency to more readily attribute causal inference from the brain to mind than vice versa with respect to BID.

CONCLUSION

In some contexts, exemplified here by aphasia and piano playing, unidirectional causality attributions may be justified. However, with respect to BID, we critically discuss presumably unjustified neuroreductionist inclinations under causal uncertainty. Finally, we emphasize the need for a presupposition-free approach in psychiatry.

When having a limb means feeling overcomplete. Xenomelia, the chronic sense of disownership and the right parietal lobe hypothesis

ABSTRACTXenomelia is a rare condition characterized by a persistent and intense desire for amputation of one or more healthy limbs. Some frequent clinical manifestations suggest the involvement of distinct neural substrates. Specifically, recent aetiopathological hypotheses about xenomelia propose a neurodevelopmental origin, highlighting the putative contribution of the right parietal lobe and right insula, known to subserve the construction of a coherent representation of the body as a whole. This literature review is aimed at analysing relevant findings about structural and functional brain correlates of xenomelia, focusing on the identification of key regions and their hemispheric distribution. Finally, implications about the potential link between xenomelia and phylogenetic development of the right parietal lobe are discussed. Despite a certain degree of heterogeneity and the spatial extension of networks involved, signs of partial right-sided lateralization of cortical nodes and left-sided lateralization of subcortical nodes emerged. Indeed, some areas-rsPL, riPL, PMC and rInsula-have been consistently found altered in xenomelia. In conclusion, the presence of both structural and functional multi-layered brain abnormalities in xenomelia suggests a multifactorial aetiology; however, as the prevalence of correlational studies, causal relationships remain to be investigated.

Body Image: Neural Basis of 'Negative' Phantom Limbs

Patients with the neurological syndrome known as body integrity dysphoria express a desire to amputate seemingly healthy parts of their body. A new study has found that this condition is linked to altered functional connectivity in a distributed neural network underlying body image.

Lower limb peripersonal space and the desire to amputate a leg

Body integrity identity disorder (BIID) is a rare condition defined by a persistent desire to amputate or paralyze a healthy limb (usually one or both of the legs). This desire arises from experiencing a mismatch between the internal body model and the actual physical/functional boundaries of the body. People with BIID show an abnormal physiological response to stimuli approaching the affected (unwanted) but not the unaffected leg, which might suggest a retracted peripersonal space (PPS: a multisensory integration zone near the body) around the unwanted limb. Thus, using a visuo-tactile interaction task, we examined leg PPS in a group of healthy men and three men with BIID who desired unilateral leg amputation. PPS size (~ 70 cm) around the unwanted BIID legs did not differ from that of healthy controls. Although the leg feels foreign in BIID, it still seems to maintain a PPS, presumably to protect it and facilitate interactions within the surrounding environment.

An Investigation of Lower Limb Representations Underlying Vision, Touch, and Proprioception in Body Integrity Identity Disorder

Individuals with Body Integrity Identity Disorder (BIID) have a (non-psychotic) longstanding desire to amputate or paralyze one or more fully-functioning limbs, often the legs. This desire presumably arises from experiencing a mismatch between one's perceived mental image of the body and the physical structural and/or functional boundaries of the body itself. While neuroimaging studies suggest a disturbed body representation network in individuals with BIID, few behavioral studies have looked at the manifestation of this disrupted lower limb representations in this population. Specifically, people with BIID feel like they are overcomplete in their current body. Perhaps sensory input, processed normally on and about the limb, cannot communicate with a higher-order model of the leg in the brain (which might be underdeveloped). We asked individuals who desire paralysis or amputation of the lower legs (and a group of age- and sex-matched controls) to make explicit and implicit judgments about the size and shape of their legs while relying on vision, touch, and proprioception. We hypothesized that BIID participants would mis-estimate the size of their affected leg(s) more than the same leg of controls. Using a multiple single-case analysis, we found no global differences in lower limb representations between BIID participants and controls. Thus, while people with BIID feel that part of the body is foreign, they can still make normal sensory-guided implicit and explicit judgments about the limb. Moreover, these results suggest that BIID is not a body image disorder, per se, and that an examination of leg representation does not uncover the disturbed bodily experience that individuals with BIID have.

A New Theory of Gender Dysphoria Incorporating the Distress, Social Behavioral, and Body-Ownership Networks

When postmortem studies related to transgender individuals were first published, little was known about the function of the various identified nuclei. Now, over 2 decades later, significant progress has been made associating function with specific brain regions, as well as in identifying networks associated with groups of behaviors. However, much of this progress has not been integrated into the general conceptualization of gender dysphoria in humans.

When postmortem studies related to transgender individuals were first published, little was known about the function of the various identified nuclei. Now, over 2 decades later, significant progress has been made associating function with specific brain regions, as well as in identifying networks associated with groups of behaviors. However, much of this progress has not been integrated into the general conceptualization of gender dysphoria in humans. I hypothesize that in individuals with gender dysphoria, the aspects of chronic distress, gender atypical behavior, and incongruence between perception of gender identity and external primary sex characteristics are all directly related to functional differences in associated brain networks. I evaluated previously published neuroscience data related to these aspects and the associated functional networks, along with other relevant information. I find that the brain networks that give individuals their ownership of body parts, that influence gender typical behavior, and that are involved in chronic distress are different in individuals with and without gender dysphoria, leading to a new theory—that gender dysphoria is a sensory perception condition, an alteration in the sense of gender influenced by the reflexive behavioral responses associated with each of these networks. This theory builds upon previous work that supports the relevance of the body-ownership network and that questions the relevance of cerebral sexual dimorphism in regard to gender dysphoria. However, my theory uses a hierarchical executive function model to incorporate multiple reflexive factors (body ownership, gender typical/atypical behavior, and chronic distress) with the cognitive, reflective process of gender identity.

Mental rotation of feet in individuals with Body Integrity Identity Disorder, lower-limb amputees, and normally-limbed controls

Body Integrity Identity Disorder (BIID) is a non-psychotic condition wherein individuals desire amputation or paralysis of one or more healthy, fully-functioning limbs (predominantly the legs). Individuals with BIID have been suggested to have a mismatch between the perceived mental representation of the body and its actual physical structure, such that their desired identity matches that of a lower-limb amputee. Accordingly, studies have reported an altered central network involving body representation of the legs in BIID, but its relationship to behavior remains unclear. In the present study, we investigated the integrity of body representation in individuals with BIID, acquired lower-limb amputees, and normally-limbed controls using an online mental rotation task. Participants judged the laterality of left and right foot images presented from different views, orientations, and of different types. We expected BIID participants to be slower for mentally rotating images that corresponded to their affected legs than lower-limb amputees and normally-limbed participants. We found that the groups did not significantly differ in their performance. All participants were slower at judging feet presented in awkward postures than natural postures, replicating previous studies and validating our online paradigm. The results are discussed in terms of the robust nature of visual and sensorimotor lower-limb representations, whether related to the self or as prototype, in the context of disturbed lower-limb integrity.

The Homuncular Jigsaw: Investigations of Phantom Limb and Body Awareness Following Brachial Plexus Block or Avulsion

Many neuropsychological theories agree that the brain maintains a relatively persistent representation of one’s own body, as indicated by vivid “phantom” experiences. It remains unclear how the loss of sensory and motor information contributes to the presence of this representation. Here, we focus on new empirical and theoretical evidence of phantom sensations following damage to or an anesthetic block of the brachial plexus. We suggest a crucial role of this structure in understanding the interaction between peripheral and central mechanisms in health and in pathology. Studies of brachial plexus function have shed new light on how neuroplasticity enables “somatotopic interferences”, including pain and body awareness. Understanding the relations among clinical disorders, their neural substrate, and behavioral outcomes may enhance methods of sensory rehabilitation for phantom limbs.

Body integrity identity disorder: clinical features and ethical dimensions

Body integrity identity disorder (BIID) is a rare and complex identity disorder described by the desire to acquire a physical disability and an associated sense of incompleteness at being able-bodied. Individuals with the disorder often delay presentation until later in life because of perceived stigma about wishing to acquire a physical disability, and may have sought amputation already through ‘underground’ means or self-harm (attempts at self-amputation). In this article we present an account of the recent history and origins of the disorder, from its early descriptions and case reports through to the current neuropsychiatric theory of right superior parietal lobe dysfunction as basis for the disorder. We consider the epidemiology, pathogenesis and clinical features of this identity disorder of bodily integrity, highlighting the associations with conditions such as gender identity disorder. With this we then discuss the ethical considerations for available treatment options, mainly elective surgical amputation.

LEARNING OBJECTIVES

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DECLARATION OF INTEREST

None.

Short parietal lobe connections of the human and monkey brain

The parietal lobe has a unique place in the human brain. Anatomically, it is at the crossroad between the frontal, occipital, and temporal lobes, thus providing a middle ground for multimodal sensory integration. Functionally, it supports higher cognitive functions that are characteristic of the human species, such as mathematical cognition, semantic and pragmatic aspects of language, and abstract thinking. Despite its importance, a comprehensive comparison of human and simian intraparietal networks is missing. In this study, we used diffusion imaging tractography to reconstruct the major intralobar parietal tracts in twenty-one datasets acquired in vivo from healthy human subjects and eleven ex vivo datasets from five vervet and six macaque monkeys. Three regions of interest (postcentral gyrus, superior parietal lobule and inferior parietal lobule) were used to identify the tracts. Surface projections were reconstructed for both species and results compared to identify similarities or differences in tract anatomy (i.e., trajectories and cortical projections). In addition, post-mortem dissections were performed in a human brain. The largest tract identified in both human and monkey brains is a vertical pathway between the superior and inferior parietal lobules. This tract can be divided into an anterior (supramarginal gyrus) and a posterior (angular gyrus) component in both humans and monkey brains. The second prominent intraparietal tract connects the postcentral gyrus to both supramarginal and angular gyri of the inferior parietal lobule in humans but only to the supramarginal gyrus in the monkey brain. The third tract connects the postcentral gyrus to the anterior region of the superior parietal lobule and is more prominent in monkeys compared to humans. Finally, short U-shaped fibres in the medial and lateral aspects of the parietal lobe were identified in both species. A tract connecting the medial parietal cortex to the lateral inferior parietal cortex was observed in the monkey brain only. Our findings suggest a consistent pattern of intralobar parietal connections between humans and monkeys with some differences for those areas that have cytoarchitectonically distinct features in humans. The overall pattern of intraparietal connectivity supports the special role of the inferior parietal lobule in cognitive functions characteristic of humans.

Role of Sexuality in Body Integrity Identity Disorder (BIID): A Cross-Sectional Internet-Based Survey Study

BACKGROUND

Body integrity identity disorder (BIID)-a strong desire for amputation or paralysis-is often accompanied by feelings and cognitions of sexual arousal, although this sexual component has been largely neglected in the recent literature.

AIM

To examine the presence of BIID-related sexual arousal in subjects with BIID and explore clinical and demographic variables of subjects with BIID who do and do not possess this sexual arousal.

METHODS

Eighty individuals with BIID responded to an internet-based survey we created. For all subjects, restoring identity was the primary motivation for preferred body modification. We collected data about respondents' demographic, clinical, and sexual characteristics. Based on responses to questions about BIID-specific sexual desires, subjects were assigned to the group with BIID-related sexual feelings (S-BIID; n = 57) or the group without such feelings (NS-BIID; n = 23).

OUTCOMES

Differences in clinical, demographic, and sexual characteristics between S-BIID and NS-BIID groups.

RESULTS

Of the respondents, 71.3% endorsed S-BIID. Subjects with S-BIID were significantly more often men, religious, and of a homosexual identity compared with the NS-BIID group. Subjects with S-BIID also significantly more often reported a change in localization and/or intensity of their BIID feelings over time. Furthermore, 66.7% of subjects with S-BIID reported S-BIID as an additional motivation for body modification. Seven of the 57 subjects with S-BIID achieved their preferred body modification through (self)-amputation, whereas none of the subjects with NS-BIID did.

CLINICAL IMPLICATIONS

BIID is a heterogeneous disorder in which subjects who self-reported comorbid sexual arousal more often resorted to (self-induced) amputation.

STRENGTHS AND LIMITATIONS

This study contains the largest BIID cohort presented in the literature and is the first to genuinely research sexuality in BIID. The first limitation is the lack of face-to-face interviews with the subjects, so no clinical diagnoses could be made. Moreover, there is an ascertainment bias because subjects were collected through the internet and in English, which excluded those who spoke other languages or subjects without an internet connection.

CONCLUSION

The present study provides preliminary evidence for a subpopulation or distinct group of individuals with BIID based on the presence of S-BIID. Blom RM, van der Wal SJ, Vulink NC, Denys D. Role of Sexuality in Body Integrity Identity Disorder (BIID): A Cross-Sectional Internet-Based Survey Study. J Sex Med 2017;14:1028-1035.

Altered White Matter and Sensory Response to Bodily Sensation in Female-to-Male Transgender Individuals

While most people take identification with their body for granted, conditions such as phantom limb pain, alien hand syndrome, and xenomelia suggest that the feeling of bodily congruence is constructed and susceptible to alteration. Individuals with xenomelia typically experience one of their limbs as over-present and aversive, leading to a desire to amputate the limb. Similarly, many transgender individuals describe their untreated sexed body parts as incongruent and aversive, and many experience phantom body parts of the sex they identify with (Ramachandran, 2008). This experience may relate to differences in brain representation of the sexed body part, as suggested in xenomelia (McGeoch et al., 2011). We utilized magnetoencephalography imaging to record brain activity during somatosensory stimulation of the breast-a body part that feels incongruent to most presurgical female-to-male (FtM)-identified transgender individuals-and the hand, a body part that feels congruent. We measured the sensory evoked response in right hemisphere somatosensory and body-related brain areas and found significantly reduced activation in the supramarginal gyrus and secondary somatosensory cortex, but increased activation at the temporal pole for chest sensation in the FtM group (N = 8) relative to non-transgender females (N = 8). In addition, we found increased white matter coherence in the supramarginal gyrus and temporal pole and decreased white matter diffusivity in the anterior insula and temporal pole in the FtM group. These findings suggest that dysphoria related to gender-incongruent body parts in FtM individuals may be tied to differences in neural representation of the body and altered white matter connectivity.

Structural and functional hyperconnectivity within the sensorimotor system in xenomelia

INTRODUCTION

Xenomelia is a rare condition characterized by the persistent and compulsive desire for the amputation of one or more physically healthy limbs. We highlight the neurological underpinnings of xenomelia by assessing structural and functional connectivity by means of whole-brain connectome and network analyses of regions previously implicated in empirical research in this condition.

METHODS

We compared structural and functional connectivity between 13 xenomelic men with matched controls using diffusion tensor imaging combined with fiber tractography and resting state functional magnetic resonance imaging. Altered connectivity in xenomelia within the sensorimotor system has been predicted.

RESULTS

We found subnetworks showing structural and functional hyperconnectivity in xenomelia compared with controls. These subnetworks were lateralized to the right hemisphere and mainly comprised by nodes belonging to the sensorimotor system. In the connectome analyses, the paracentral lobule, supplementary motor area, postcentral gyrus, basal ganglia, and the cerebellum were hyperconnected to each other, whereas in the xenomelia-specific network analyses, hyperconnected nodes have been found in the superior parietal lobule, primary and secondary somatosensory cortex, premotor cortex, basal ganglia, thalamus, and insula.

CONCLUSIONS

Our study provides empirical evidence of structural and functional hyperconnectivity within the sensorimotor system including those regions that are core for the reconstruction of a coherent body image. Aberrant connectivity is a common response to focal neurological damage. As exemplified here, it may affect different brain regions differentially. Due to the small sample size, our findings must be interpreted cautiously and future studies are needed to elucidate potential associations between hyperconnectivity and limb disownership reported in xenomelia.

Infertility, impotence, and emasculation--psychosocial contexts for abandoning reproduction

From a Darwinian perspective we live to reproduce, but in various situations genetic males elect not to reproduce by choosing medical treatments leading to infertility, impotence, and, in the extreme, emasculation. For many men, infertility can be psychologically distressing. However, for certain genetic males, being infertile may improve their quality of life. Examples include (1) men who seek vasectomy, (2) individuals with Gender Dysphoria (e.g., transwomen, and modern day voluntary eunuchs), (3) most gay men, and (4) men treated for testicular and prostate cancer. Men who desire vasectomy typically have a Darwinian fitness W >1 at the time of their vasectomies; i.e., after they have their desired number of offspring or consider themselves past an age for parenting newborns. In contrast, prostate and testicular cancer patients, along with individuals with extreme Gender Dysphoria, do not necessarily seek to be sterile, but accept it as an unavoidable consequence of the treatment for their condition undertaken for survival (in case of cancer patients) or to achieve a better quality of life (for those with Gender Dysphoria). Most gay men do not father children, but they may play an avuncular role, providing for their siblings’ offspring's welfare, thus improving their inclusive fitness through kin selection. In a strictly Darwinian model, the primary motivation for all individuals is to reproduce, but there are many situations for men to remove themselves from the breeding populations because they have achieved a fitness W ≥1, or have stronger medical or psychological needs that preclude remaining fertile.

Neuroanatomical correlates of perceptual aberrations in psychosis

BACKGROUND

Aberrations in body perception are common in psychotic disorders. The insula and temporoparietal junction (TPJ) are involved in body ownership and spatial perception suggesting that abnormal structure of these regions might be related to the expression of perceptual aberrations in psychosis.

METHODS

58 individuals with a primary psychotic disorder and 40 healthy subjects completed the Chapman Perceptual Aberration Scale (PAS) and underwent structural magnetic resonance imaging (MRI). Grey matter volume was extracted from a-priori defined TPJ, whole insula, and insula sub-division regions-of-interest (ROIs) and correlated with PAS scores. Additionally, a voxel-based morphometry (VBM) analysis examining the correlation between voxel-wise grey matter volume and PAS scores was conducted.

RESULTS

PAS scores in psychosis patients correlated with bilateral whole insula (right: r=-0.30, p=0.026; left: r=-0.35, p=0.011) and right TPJ (r=-0.27, p=0.024) volumes. The correlation between grey matter volume and PAS was strongest for the posterior sub-division of the insula (right: r=-0.32, p=0.017; left: r=-0.37, p=0.006). VBM analyses confirmed the ROI results: negative correlations with PAS were identified in clusters within the posterior and dorsal anterior insula, and the right TPJ. An exploratory, whole-brain analysis also revealed two additional regions located in the left middle orbitofrontal gyrus and left inferior temporal gyrus that inversely correlated with PAS scores.

CONCLUSIONS

Perceptual aberrations in individuals with psychosis are related to lower grey matter volume in the insula and TPJ. This relationship was strongest in the posterior region of the insula and right TPJ; brain areas that have been implicated in interoception and somesthesis.

When less is more - Implicit preference for incomplete bodies in xenomelia

Individuals with xenomelia identify with an amputated rather than with their physically complete, healthy body. They often mimic amputees and show a strong admiration of and sexual attraction towards them. Here we investigated for the first time empirically whether such unusual preference for amputated bodies is present also on an implicit level. Using the well-validated Implicit Association Test we show that individuals with xenomelia manifested a stronger implicit and explicit preference for amputated bodies than a normally-limbed control group and a group of involuntary amputees did. Interestingly, the two latter groups did not differ in their implicit and explicit preference for complete versus amputated bodies. These findings are an important step in understanding how deeply rooted attitudes about a socially normative body appearance may be influenced by a developmentally disordered experience of one's own bodily self. We conclude that this is the first behavioral evidence demonstrating a conflict of self-identification on an implicit level and this enriches current understandings of xenomelia as a primarily neurological disorder.

Limb amputation and other disability desires as a medical condition

Some people have a profound dissatisfaction with what is considered an able-bodied state by most others. These individuals desire to be disabled, by conventional standards. In this Review, we integrate research findings about the desire for a major limb amputation or paralysis (xenomelia). Neuropsychological and neuroimaging explorations of xenomelia show functional and structural abnormalities in predominantly right hemisphere cortical circuits of higher-order bodily representation, including affective and sexual aspects of corporeal awareness. These neural underpinnings of xenomelia do not necessarily imply a neurological cause, and a full understanding of the condition requires consideration of the interface between neural and social contributions to the bodily self and the concept of disability. Irrespective of cause, disability desires are accompanied by a disabling bodily dysphoria, in many respects similar to gender dysphoria, and we suggest that they should be considered a mental disorder.

The Desire for Amputation or Paralyzation: Evidence for Structural Brain Anomalies in Body Integrity Identity Disorder (BIID)

Background

Body Integrity Identity Disorder (BIID) is a condition in which individuals perceive a mismatch between their internal body scheme and physical body shape, resulting in an absolute desire to be either amputated or paralyzed. The condition is hypothesized to be of congenital nature, but evidence for a neuro-anatomical basis is sparse.

Methods

We collected T1-weighted structural magnetic resonance imaging scans on a 3T scanner in eight individuals with BIID and 24 matched healthy controls, and analyzed the data using voxel-based morphometry.

Results

The results showed reduced grey matter volume in the left dorsal and ventral premotor cortices and larger grey matter volume in the cerebellum (lobule VIIa) in individuals with BIID compared to controls.

Conclusion

The premotor cortex and cerebellum are thought to be crucial for the experience of body-ownership and the integration of multisensory information. Our results suggest that BIID is associated with structural brain anomalies and might result from a dysfunction in the integration of multisensory information, leading to the feeling of disunity between the mental and physical body shape.

Age prediction on the basis of brain anatomical measures

In this study, we examined whether age can be predicted on the basis of different anatomical features obtained from a large sample of healthy subjects (n = 3,144). From this sample we obtained different anatomical feature sets: (1) 11 larger brain regions (including cortical volume, thickness, area, subcortical volume, cerebellar volume, etc.), (2) 148 cortical compartmental thickness measures, (3) 148 cortical compartmental area measures, (4) 148 cortical compartmental volume measures, and (5) a combination of the above-mentioned measures. With these anatomical feature sets, we predicted age using 6 statistical techniques (multiple linear regression, ridge regression, neural network, k-nearest neighbourhood, support vector machine, and random forest). We obtained very good age prediction accuracies, with the highest accuracy being R²  = 0.84 (prediction on the basis of a neural network and support vector machine approaches for the entire data set) and the lowest being R²  = 0.40 (prediction on the basis of a k-nearest neighborhood for cortical surface measures). Interestingly, the easy-to-calculate multiple linear regression approach with the 11 large brain compartments resulted in a very good prediction accuracy (R²  = 0.73), whereas the application of the neural network approach for this data set revealed very good age prediction accuracy (R²  = 0.83). Taken together, these results demonstrate that age can be predicted well on the basis of anatomical measures. The neural network approach turned out to be the approach with the best results. In addition, it was evident that good prediction accuracies can be achieved using a small but nevertheless age-representative dataset of brain features. Hum Brain Mapp 38:997-1008, 2017. © 2016 Wiley Periodicals, Inc.

Elective amputation of a "healthy limb"

Patients with body integrity identity disorder (BIID) experience a strong desire for amputation from very early on. BIID patients are often dismissed when they share their wish for amputation with surgeons. Consequently, patients resort to self-amputation, including complications and sometimes death. BIID patients are not psychotic and are mentally competent to oversee the consequences of an elective amputation. The authors offer arguments in favor of elective amputation.

Potential relationship of self-injurious behavior to right temporo-parietal lesions

Self-injurious behavior (SIB) is associated with several neurologic and psychiatric syndromes but rarely with focal lesions. Two patients with lesions of the right temporo-parietal junction presented to psychiatric inpatient services with SIB in the absence of notable neurologic deficits or suicidal ideation. Right temporo-parietal lesions may be associated with disturbances of agency and body ownership, both of which may facilitate SIB. Misoplegia, or hatred of a limb, may be associated with SIB and has been reported without hemiplegia with a right temporo-parietal lesion. Further study is warranted to improve our understanding of the mechanisms underlying SIB.

Shape alterations of basal ganglia and thalamus in xenomelia

Xenomelia is a rare condition characterized by the persistent desire for the amputation of physically healthy limbs. Associations with morphological alterations such as reduced cortical thickness and surface area. Nothing is known, however, about the potential involvement of subcortical structures. The thalamus and basal ganglia process, relay, and integrate sensorimotor information and are involved in the preparation and execution of movements. Moreover, both of these structures house somatotopic representations of all body parts. We therefore investigated subcortical correlates of xenomelia by assessing basal ganglia and thalamus by means of vertex-wise shape analyses. For that purpose, we compared the shape of the thalamus, putamen, caudate nucleus, and the pallidum in 13 men suffering from xenomelia, all desiring a leg amputation, compared to 13 healthy control men. We hypothesised that the target leg is misrepresented in subcortical structures of individuals with xenomelia, especially in locations with a somatotopic representation. Shape analyses showed thinning of bilateral dorsomedial putamina, left ventromedial caudate nucleus and left medial pallidum associated with xenomelia. This was accompanied by thickening of bilateral lateral pallida and the left frontolateral thalamus. These shape differences were mainly located in sensorimotor areas of somatotopic leg representations. The present study provides strong evidence for shape differences in striatal, pallidal, and thalamic subregions housing subcortical body part representations. It adds to previously described neural correlates of a condition one can barely empathize with and invites future connectivity analyses in cortico-subcortical networks.

Body integrity identity disorder crosses culture: case reports in the Japanese and Chinese literature

Body integrity identity disorder (BIID) is a condition in which people do not perceive a part of their body as their own, which results in a strong desire for amputation or paralyzation. The disorder is likely to be congenital due to its very early onset. The English literature describes only Western patients with BIID, suggesting that the disorder might be merely prevalent in the West. To scrutinize this assumption, and to extend our knowledge of the etiology of BIID, it is important to trace cases with BIID in non-Western populations. Our objective was to review Chinese and Japanese literature on BIID to learn about its presence in populations with a different genetic background. A systematic literature search was performed in databases containing Japanese and Chinese research, published in the respective languages. Five Japanese articles of BIID were identified which described two cases of BIID, whereas in the Chinese databases only BIID-related conditions were found. This article reports some preliminary evidence that BIID is also present in non-Western countries. However, making general statements about the biological background of the disorder is hampered by the extremely low number of cases found. This low number possibly resulted from the extreme secrecy associated with the disorder, perhaps even more so in Asian countries.

Neuroanatomical Correlates of Theory of Mind Deficit in Parkinson's Disease: A Multimodal Imaging Study

BACKGROUND

Parkinson's disease (PD) patients show theory of mind (ToM) deficit since the early stages of the disease, and this deficit has been associated with working memory, executive functions and quality of life impairment. To date, neuroanatomical correlates of ToM have not been assessed with magnetic resonance imaging in PD. The main objective of this study was to assess cerebral correlates of ToM deficit in PD. The second objective was to explore the relationships between ToM, working memory and executive functions, and to analyse the neural correlates of ToM, controlling for both working memory and executive functions.

METHODS

Thirty-seven PD patients (Hoehn and Yahr median = 2.0) and 15 healthy controls underwent a neuropsychological assessment and magnetic resonance images in a 3T-scanner were acquired. T1-weighted images were analysed with voxel-based morphometry, and white matter integrity and diffusivity measures were obtained from diffusion weighted images and analysed using tract-based spatial statistics.

RESULTS

PD patients showed impairments in ToM, working memory and executive functions; grey matter loss and white matter reduction compared to healthy controls. Grey matter volume decrease in the precentral and postcentral gyrus, middle and inferior frontal gyrus correlated with ToM deficit in PD. White matter in the superior longitudinal fasciculus (adjacent to the parietal lobe) and white matter adjacent to the frontal lobe correlated with ToM impairment in PD. After controlling for executive functions, the relationship between ToM deficit and white matter remained significant for white matter areas adjacent to the precuneus and the parietal lobe.

CONCLUSIONS

Findings reinforce the existence of ToM impairment from the early Hoehn and Yahr stages in PD, and the findings suggest associations with white matter and grey matter volume decrease. This study contributes to better understand ToM deficit and its neural correlates in PD, which is a basic skill for development of healthy social relationships.