Topography Body

[Flaviano Goldammer]

Mybrother is an unusual medical case; he was born with numerous disabilities and survived meningitis with severe brain damage. I became a physician because of him, and in medical school, I unraveled his illness one lecture at a time. I learned about his physical disabilities in anatomy, examining cadaver joints and organs. In neurology and pulmonology, I learned about his breathing problems, and in the cardiac ICU, I learned how to put it all together to understand the reasons his heart kept failing him.

The first time I made an incision during surgery, I was a third-year medical student scrubbed into a kidney transplant. I carefully cut the skin and opened the abdomen down to the peritoneum, smooth as saran wrap around the organs. I wanted to touch every one of them.

When the kidney fails, there are distinct metabolic abnormalities. Electrolytes become imbalanced, the body becomes acidotic, and nitrogenous waste compounds accumulate. The resulting uremia eventually leads to a number of end organ manifestations, including the decline of the central nervous system. One of my professors in medical school described dying from end-stage renal disease as much like falling asleep.

I have thought often about the life my brother has lived thus far, and how the end of it might look. As a doctor, I know how I would want to die, at home with the people I love, with as minimal medical intervention as possible. Despite our family conversations about his health, death remains unfathomable. The thought devastates me.

In some small way, the thought of giving my organ feels like a tangible manifestation of love for my brother, who has shared a lifetime alongside me, and for my mother, who was our first bodily home. A part of myself would always be with him, at least on this earth. Does that make it more or less divine?

Dr. Mariam Gomaa is a physician and writer based in Washington, DC. Her writing has appeared in Time, NBC News, and Readings for Diversity and Social Justice (Fourth Edition), among other publications.

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The stitch pattern for Self-Portrait is a topographic map of my own body. Its topography was determined by chalking quarter-inch elevations following an even beam of light projected by a laser leveler while I lay underneath the fabric.

The stitch pattern in Meet and Separate is a topographical map of a couple holding each other as in sleep. The colors refer to separate sides of the bed, determining two halves that both contrast and overlap. Where two colors meet, I calculated the combined value in a computer diagram and tried to match those values when hand-dyeing the fabric.

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The cytoarchitectonic map as proposed by Brodmann currently dominates models of human sensorimotor cortical structure, function, and plasticity. According to this model, primary motor cortex, area 4, and primary somatosensory cortex, area 3b, are homogenous areas, with the major division lying between the two. Accumulating empirical and theoretical evidence, however, has begun to question the validity of the Brodmann map for various cortical areas. Here, we combined in vivo cortical myelin mapping with functional connectivity analyses and topographic mapping techniques to reassess the validity of the Brodmann map in human primary sensorimotor cortex. We provide empirical evidence that area 4 and area 3b are not homogenous, but are subdivided into distinct cortical fields, each representing a major body part (the hand and the face). Myelin reductions at the hand-face borders are cortical layer-specific, and coincide with intrinsic functional connectivity borders as defined using large-scale resting state analyses. Our data extend the Brodmann model in human sensorimotor cortex and suggest that body parts are an important organizing principle, similar to the distinction between sensory and motor processing.

Copyright: 2021 Cazzato et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Further studies have recently shown that both acute and recovered AN (RAN) patients also display a reduced responsivity to the anticipation of CT-optimal touch, both in terms of neural response localized to the ventral mid-insula, and in terms of predicted pleasantness of touch [33, 39]. Taken together, these findings suggest that in AN there is a dysregulation in the ability to correctly predict and interpret interoceptive stimuli, including CT-based pleasantness of touch.

The purpose of this study was threefold. First, we examined whether pleasantness of touch varies across different hairy skin body sites that are innervated by CTs. In other mammals these nerves are called C-low threshold mechanoreceptors (CLTM) and in a study with mice it was shown that CLTMs more densely innervate proximal body sites, such as the back and head, compared to distal sites [50]. In a recent study with humans where participants viewed video clips of touch to different body sites and were asked how pleasant they thought the touch was to the receiver, sites that are more proximal were also reported as being more pleasant [51]. However, the classical approach for characterising CT (actual) responses has usually limited its focus to the forearm, compared to the glabrous skin of the palm, which should be CT-free. To the best of our knowledge, only three studies have looked so far at differences in pleasantness ratings at several stroking velocities, across several skin sites [3, 4, 52], thus characterising the pleasantness/stroking velocity profile for each of these body sites. In the current study, we wanted to replicate and extend previous findings by targeting additional body sites to include the cheek, back and abdomen.

Participants were recruited internally through the Liverpool John Moores University (LJMU) research participation system for undergraduate Psychology students in exchange for course credits and externally through poster advertisements situated in public locations, social media and through individuals known to the researchers. In line with previous literature analysing body perception and eating behaviours, the current study employed a population of only female participants [60, 80, 81]. Indeed, literature on the prevalence and the phenomenology of EDs in male populations is still limited [82]. All participants, except one, were right-handed as assessed by the Edinburgh Handedness Inventory [83]. All reported normal or corrected to normal vision and they were in good health, free of psychotropic or vasoactive medication, with no current or history of any psychiatric or neurological disease, no skin conditions (e.g. psoriasis, eczema, etc.) and not pregnant. Participants provided written informed consent prior to testing and were debriefed at the end of the experiment. All procedures were approved by the Research Ethics University Committee (UREC, approval n.: 19NSP009) of Liverpool John Moores University and complied with the ethical standards of the 1964 Declaration of Helsinki.

General procedure. Participants were lying semi-horizontally in a comfortable, reclining dental chair whilst receiving manual brush strokes. They were instructed to remain still with their arms resting on the chair armrest. Although during each trial participants kept their eyes open, the position on the chair prevented participants from seeing the stroking procedure at the varying body sites.

During each trial, strokes were delivered for 6 secs on a 9 cm surface at one of three set velocities: 0.3 cm/s, 3 cm/s, and 30 cm/s. The experimenter was trained to deliver stroking touch with a constant pressure of 220 mN, which was calibrated using a high precision digital scale. The stroking was delivered in a proximal to distal direction.

Overall, the stroking task consisted of 5 blocks: one block for each body site. Each block consisted of 9 trials, with 3 trials for each velocity. Across the 5 blocks, participants experienced a total of 15 CT-optimal trials (3 cm/s, 2 strokes per trial), 15 non-CT optimal fast touch trials (30 cm/s, 20 strokes per trial) and 15 non-CT optimal slow touch trials (0.3 cm/s, 1/5 of a stroke per trial corresponding to 1.8 cm). Participants were randomly assigned to receive the experimental blocks in one of 5 pseudo-randomised orders, which ensured no two consecutive trials were the same.

A visual metronome, programmed in PsychoPy, was presented on a computer screen behind the participant [91, 92] and guided the researcher in delivering the brush strokes at one of the three velocities.

Participants were lying semi-horizontally in a comfortable, reclining chair whilst receiving manual brush strokes. In randomised blocks (each one corresponding to one body site), participants were asked to rate the pleasantness and intensity of the touch delivered by a female experimenter to the palm, face, abdomen, back and forearm at 3 cm/s (CT-optimal stroking) and 0.3 cm/s and 30 cm/s (non-CT optimal stroking) velocities.

This study aimed to: a) investigate whether pleasantness and intensity ratings of touch vary across different body sites, b) explore associations between EDs and BDD traits with gentle touch applied at several body sites and in particular at emotionally salient body sites, i.e., abdomen and face; c) explore the relationship between self-reports of interoceptive sensibility and of emotional awareness with tactile experience at these varying body sites.

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