Everyone has felt those tingling, tickly sensations occurring spontaneously all over the body in the absence of stimuli. But does anyone know where they come from? Here, right-handed subjects were asked to focus on one hand while looking at it and while looking away and subsequently to map and describe the spatial and qualitative attributes of sensations arising spontaneously. The spatial distribution of spontaneous sensations followed a proximo-distal gradient, similar to the one previously described for the density of receptive units. (...) The intensity and spatial extent of the reported sensations were modulated by the focusing condition, especially in respect of the left hand. Convergent focusing acted upon the conscious perception of sensations by enhancing or suppressing them. To our knowledge, this is the first ever study of spontaneous sensations, and it offers considerable insight into their sources. The presence of the proximo-distal distributional gradient is a clear sign that receptive units are involved. The enhancement/suppression effects also confirm the involvement of attention. Finally, left-hand dominance suggests several right-hemisphere processes may be involved, such as spatial and tactile perception, and probably interoception. (shrink)

Reports of phantom limbs amongst aplasics have often been presented as evidence that body image is ‘hard-wired’ in the brain and that neither sensory input nor proprioceptive feedback are essential to its formation. Although attempts have been made to account for these phantoms by other means, these have been on a case by case basis and no satisfactory alternative framework has been proposed. This paper collates the accounts of aplasic phantoms and presents them as compatible with a four-part hypothesis, in (...) which body image is learnt from experience during both pre- and post-natal development, and in which cross-cortical connections and mirror neurons play prominent roles. This model unites several previously disparate theories to offer a viable solution to several longstanding phantom limb mysteries and serves to highlight avenues worthy of further inquiry. (shrink)

This paper brings neuroscientific experiments into relation with concepts from phenomenological philosophy to investigate phantom sensations from the perspective of embodied subjectivity. Using a mirror device to create intersensory effects in subjects experiencing phantom sensations, one can create illusions aiming at alleviating phantom pain. Neuroplasticity as a general property of the brain and cortical remapping as a specific mechanism underlying the success of this procedure are interpreted with the phenomenological notions of body image, body schema, and body memory. It is (...) argued that a phantom can be understood as an ambiguous unity of body-imagistic neglect and body-schematic remembering. This neurophenomenological approach highlights the significance of the polarity of subjective-objective embodied experience one the one hand, and the spatial and temporal horizons of the emergence of phantoms on the other. Thereby, implicit and explicit forms of remembering, habitual and reflective modes of behavioural and cognitive self-representation and -understanding can be compared according to how the body integrates its various sensations. (shrink)

People’s awareness of tactile stimuli has been investigated in far less detail than their awareness of stimuli in other sensory modalities. In an attempt to fill this gap, we provide an overview of studies that are pertinent to the topic of tactile consciousness. We discuss the results of research that has investigated phenomena such as “change blindness”, phantom limb sensations, and numerosity judgments in tactile perception, together with the results obtained from the study of patients affected by deficits that can (...) adversely affect tactile perception such as neglect, extinction, and numbsense. The similarities as well as some of the important differences that have emerged when visual and tactile conscious information processing have been compared using similar experimental procedures are highlighted. We suggest that conscious information processing in the tactile modality cannot be separated completely from the more general processing of spatial information in the brain. Finally, the importance of considering tactile consciousness within the larger framework of multisensory information processing is also discussed. (shrink)

This article reviews the potential use of visual feedback, focusing on mirror visual feedback, introduced over 15 years ago, for the treatment of many chronic neurological disorders that have long been regarded as intractable such as phantom pain, hemiparesis from stroke and complex regional pain syndrome. Apart from its clinical importance, mirror visual feedback paves the way for a paradigm shift in the way we approach neurological disorders. Instead of resulting entirely from irreversible damage to specialized brain modules, some of (...) them may arise from short-term functional shifts that are potentially reversible. If so, relatively simple therapies can be devised—of which mirror visual feedback is an example—to restore function. (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)

I argue that an analogy between pains and sounds suggests a way to give an objective account of pain which fits well with a naïve perceptualist account of feeling pain. According to the proposed metaphysical account, pains are relational physical events with shared qualitative nature, each of which is constituted by tissue damage and the activation of nociceptors. I proceed to show that the metaphysical proposal is compatible with platitudes about pains being animate, private, and self-intimating states.

In this article, we examine phantom limb syndrome to gain insights into how the brain functions as the mind and how consciousness arises. We further explore our previously proposed consciousness model in which consciousness and body schema arise when information from throughout the body is processed by corticothalamic feedback loops and integrated by the thalamus. The parietal lobe spatially maps visual and non-visual information and the thalamus integrates and recreates this processed sensory information within a three-dimensional space termed the ‘‘3D (...) default space.’’ We propose that phantom limb syndrome and phantom limb pain arise when the afferent signaling from the amputated limb is lost but the neural circuits remain intact. In addition, integration of conflicting sensory information within the default 3D space and the loss of inhibitory afferent feedback to efferent motor activity from the amputated limb may underlie phantom limb pain. (shrink)

This review addresses the role of early sensory areas in the awareness of tactile information in humans. The results of recent studies dealing with this important topic are critically discussed: In particular, we report on evidence from neuropsychology, neurophysiology, neuroimaging, and behavioral experiments that have highlighted the crucial role played by the primary somatosensory cortex in mediating our awareness of tactile information. Phenomena, such as tactile hallucinations, tactile illusions, the perception of supernumerary limbs, and synaesthesia are also discussed. The research (...) reviewed here clearly shows that the activation of SI is necessary, but not sufficient, for the awareness of touch. On the basis of the evidence outlined here, we propose a neurocognitive model that provides a conceptual framework in which to interpret the results of the literature regarding tactile consciousness. (shrink)