Summary Apotemnophilia, or body integrity image disorder (BIID), is characterised by a feeling of mismatch between the internal feeling of how one’s body should be and the physical reality of how it actually is. Patients with this condition have an often overwhelming desire for an amputation- of a specific limb at a specific level. Such patients are not psychotic or delusional, however, they do express an inexplicable emotional abhorrence to the limb they wish removed. It is also known that such (...) patients show a left-sided preponderance for their desired amputation. Often they take drastic action to be rid of the offending limb. Given the left-sided bias, emotional rejection and specificity of desired amputation, we suggest that there are clear similarities to be drawn between BIID and somatoparaphrenia. In this rare condition, which follows a right parietal stroke, the patient rejects (usually) his left arm as ‘‘alien’’. We go on to hypothesis that a dysfunction of the right parietal lobe is also the cause of BIID. We suggest that this leads to an uncoupling of the construct of one’s body image in the right parietal lobe from how one’s body physically is. This hypothesis would be amenable to testing by response to cold-water vestibular caloric stimulation, which is known to temporarily treat somatoparaphrenia. It could also be investigated using functional brain imaging and skin conductance response. If correct our hypothesis not only suggests why BIID arises, but also, in caloric stimulation a therapeutic avenue for this chronic and essentially untreatable condition. (shrink)

We propose that synesthetic cross‐activation between the primary auditory cortex and the anatomically adjacent insula may help explain two puzzling conditions—autonomous sensory meridian response (ASMR) and misophonia—in which quotidian sounds involuntarily trigger strong emotional responses. In ASMR the sounds engender relaxation, while in misophonia they trigger an aversive response. The insula both plays an important role in autonomic nervous system control and integrates multiple interoceptive maps representing the physiological state of the body to substantiate a dynamic representation of emotional wellbeing. (...) We propose that in ASMR cross‐activation of the map for affective (sensual) touch leads to an increase in subjective wellbeing and parasympathetic activity. Conversely, in misophonia the effect of the cross‐activation is to decrease emotional wellbeing and increase sympathetic activity. Our hypothesis also illuminates the connection between hearing and wellbeing more broadly and helps explain why so many people experience decreased wellbeing from modern urban soundscapes. (shrink)

How the brain constructs one's inner sense of gender iden-tity is poorly understood. On the other hand, the phenomenon of phantom sensations-- the feeling of still having a body-part after amputation--has been much studied. Around 60% of men experience a phantom penis post-penectomy. As transsexuals report a mismatch between their inner gender identity and that of their body, we won-dered what could be learnt from this regarding innate gender-specific body image. We surveyed male-to-female transsexuals regarding the incidence of phantoms post-gender (...) reassignment surgery. Addition-ally, we asked female-to-male transsexuals if they had ever had the sensation of having a penis when there was not one physically there. In post-operative male-to-female transsexuals the incidence of phan-tom penises was significantly reduced at 30%. Remarkably, over 60% of female-to-male transsexuals also reported phantom penises. We explain the absence/presence of phantoms here by postulating a mis-match between the brain's hardwired gender-specific body image and the external somatic gender. Further studies along these lines may provide penetrating insights into the question of how nature and nur-ture interact to produce our brain-based body image. (shrink)

Summary Transsexuals are individuals who identify as a member of the gender opposite to that which they are born. Many transsexuals report that they have always had a feeling of a mismatch between their inner gender-based ‘‘body image’’ and that of their body’s actual physical form. Often transsexuals undergo gender reassignment surgery to convert their bodies to the sex they feel they should have been born. The vivid sensation of still having a limb although it has been amputated, a phantom (...) limb, was first described by Weir Mitchell over a century ago. The same phenomenon is also occurs after amputation of the penis or a breast. Around 60% of men who have had to have their penis amputated for cancer will experience a phantom penis. It has recently been shown that a significant factor in these phantom sensations is ‘‘cross-activation’’ between the de-afferented cortex and surrounding areas. Despite this it also known that much of our body image is innately ‘‘hard-wired’’ into our brains; congenitally limbless patients can still experience phantom sensations. We hypothesise that, perhaps due to a dissociation during embryological development, the brains of transsexuals are ‘‘hard-wired’’ in manner, which is opposite to that of their biological sex. We go on to predict that male-to-female transsexuals will be much less likely to experience a phantom penis than a ‘‘normal’’ man who has had his penis amputated for another reason. The same will be true of female-to-male transsexuals who have had breast removal surgery. We also predict that some female-to-male transsexuals will have a phantom penis even although there is not one physically there. We believe that this is an easily testable hypothesis, which, if correct, would offer insights into both the basis of transsexuality and provide farther evidence that we have a gender specific body image, with a strong innate component that is ‘‘hard-wired’’ into our brains. This would furnish us with a better understanding the mechanism by which nature and nurture interact to link the brain-based internal body image with external sexual morphology.. (shrink)

It is hypothesized that repeated, non‐invasive stimulation of the vestibular (balance) system, via a small electrical current to the skin behind the ears, will cause the brain centers that control energy homeostasis to shift the body toward a leaner physique. This is because these centers integrate multiple inputs to, in effect, fix a set‐point for body fat, which though difficult to alter is not immutable. They will interpret repeated stimulation of the parts of the vestibular system that detect acceleration as (...) a state of chronic activity. During such a physiologically challenging time it is preferable, from an energy homeostasis viewpoint, to both utilize fat reserves, and reduce the volume of these reserves and thus the energy cost of carrying them around. Hence, this type of vestibular stimulation could potentially be a therapeutic option for metabolic syndrome disorders such as obesity. This hypothesis is eminently testable via a clinical trial. (shrink)