The right SPL is a cortical area that appears ideally placed to unify disparate sensory inputs to create a coherent sense of having a body. The authors propose that inadequate activation of the right SPL leads to the unnatural situation in which the sufferers can feel the limb in question being touched without it actually incorporating into their body image, with a resulting desire for amputation. The authors introduce the term 'xenomelia' as a more appropriate name than apotemnophilia or body integrity identity disorder, for what appears to be an unrecognised right parietal lobe syndrome.

Apotemnophilia, a disorder that blurs the distinction between neurology and psychiatry, is characterized by the intense and longstanding desire for amputation of a specific limb. Here we present evidence from two individuals suggestive that this condition, long thought to be entirely psychological in origin, actually has a neurological basis. We found heightened skin conductance response to pinprick below the desired line of amputation. We propose apotemnophilia arises from congenital dysfunction of the right superior parietal lobule and its connection with the insula.

Participants who responded best to CVS had suffered strokes that spared and permitted activation of the dominant parieto-insular vestibular cortex (PIVC), which is known to be located in the non-dominant hemisphere. These findings tie in closely with the thermosensory disinhibition hypothesis for central pain, which leads us to propose that vestibular stimulation may alleviate CPSP from cross activation between the PIVC and the thermosensory cortex in the adjacent dorsal posterior insula. Alternatively, if one views vestibular function and thermoregulation as part of a larger interoceptive system that exists to maintain homeostasis, then it is possible they share a common integrative mechanism in the brainstem, which may act to reset the balance in central pain.

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Following limb amputation patients continue to feel the vivid presence of a phantom limb. A majority of patients also experience pain in the phantom and sometimes (as in our case DS) the pain is severe. Remarkably we find that optically 'resurrecting' the phantom with a mirror and using a lens to make the phantom appear to shrink caused the pain to 'shrink' as well.

Central post-stroke pain syndrome develops in a minority of patients following a stroke. The most usual causative lesion involves the lateral thalamus. The classic presentation is of severe, unrelenting pain that involves the entire contralateral half of the body. It is largely refractory to current treatments. We found that in two patients with this condition their pain was substantially improved by vestibular caloric stimulation, whereas placebo procedures had no effect. We proposed that this is because vestibular stimulation activates the posterior insula, which in turn inhibits the generation of pain in the anterior cingulate.

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We propose that synesthetic cross-activation between the primary auditory cortex and the anatomically adjacent insula may help explain two puzzling conditionsautonomous 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 crossactivation 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.