Acquisition of ownership illusion with self-disownership in neurological patients

The multisensory regions in frontoparietal cortices play a crucial role in the sense of body and self. Disrupting this sense may lead to a feeling of disembodiment, or more generally, a sense of disownership. Experimentally, this altered consciousness disappears during illusory own-body perceptions, increasing the intensity of perceived ownership for an external virtual limb. In many clinical conditions, particularly in individuals with a discontinuous or absent sense of bodily awareness, the brain may effortlessly create a convincing feeling of body ownership over a surrogate body or body part. The immediate visual input dominates the current bodily state and induces rapid plastic adaptation that reconfigures the dynamics of bodily representation, allowing the brain to acquire an alternative sense of body and self. Investigating strategies to deconstruct the lack of a normal sense of bodily ownership, especially after a neurological injury, may aid the selection of appropriate clinical treatment

Embodying functionally relevant action sounds in patients with spinal cord injury

Growing evidence indicates that perceptual-motor codes may be associated with and influenced by actual bodily states. Following a spinal cord injury (SCI), for example, individuals exhibit reduced visual sensitivity to biological motion. However, a dearth of direct evidence exists about whether profound alterations in sensorimotor traffic between the body and brain influence audio-motor representations. We tested 20 wheelchair-bound individuals with lower skeletal-level SCI who were unable to feel and move their lower limbs, but have retained upper limb function. In a two-choice, matching-to-sample auditory discrimination task, the participants were asked to determine which of two action sounds matched a sample action sound presented previously. We tested aural discrimination ability using sounds that arose from wheelchair, upper limb, lower limb, and animal actions. Our results indicate that an inability to move the lower limbs did not lead to impairment in the discrimination of lower limb-related action sounds in SCI patients. Importantly, patients with SCI discriminated wheelchair sounds more quickly than individuals with comparable auditory experience (i.e. physical therapists) and inexperienced, able-bodied subjects. Audio-motor associations appear to be modified and enhanced to incorporate external salient tools that now represent extensions of their body schema

Body image distortions following spinal cord injury

Background: Following spinal cord injury (SCI) or anaesthesia, people may continue to experience feelings of the size, shape, and posture of their body, suggesting that the conscious body image is not fully determined by immediate sensory signals. How this body image is affected by changes in sensory inputs from, and motor outputs to the body remains unclear. Methods: We tested paraplegic and tetraplegic SCI patients on a task that yields quantitative measures of body image. Participants were presented with an anchoring stimulus on a computer screen and told to imagine that the displayed body part was part of a standing mirror image of themselves. They then identified the position on the screen, relative to the anchor, where each of several parts of their body would be located. Veridical body dimensions were identified based on measurements and photographs of participants. Results: Compared to age-matched controls, paraplegic and tetraplegic patients alike perceived their torso and limbs as elongated relative to their body width. No effects of lesion level were found. Conclusions: The common distortions in body image across patient groups, despite differing SCI levels, imply that a body image may be maintained despite chronic sensory and motor loss. Systematic alterations in body image follow SCI, though our results suggest these may reflect prolonged changes in body posture and wheelchair use, rather than loss of specific sensorimotor pathways. These findings provide new insight into how the body image is maintained, and may prove useful in treatments that intervene to manipulate the body image

Pathology of disappearing bone disease: a case report with immunohistochemical study.

A case of disappearing bone disease of the proximal femur is reported with histopathological and immunohistochemical studies. There was a densely packed cellular tissue, positive to endothelial antibodies, in areas of massive bone destruction. A more differentiated vascular tissue was present where trabecular cancellous or cortical bone was preserved with only focal zones of accelerated bone remodelling. The self-limited course correlates well with two phases of evolution of the histopathological lesions with neoplastic-like proliferation of endothelial cells corresponding to the rapid and massive bone destruction, and a later differentiation of the cells in mature vascular structures, but still with accelerated bone resorption which is partly compensated by appositional activity

Perceived Psychological Restorativeness in Relation to Individual and Environmental Variables: A Study Conducted at Poetto Beach in Sardinia, Italy

This study examines how objective, social, and perceived environmental conditions in a blue space are associated with the perception of psychological restorativeness. We collected data between April 2021 and February 2022 at Poetto Beach in Sardinia, Italy. The participants (N = 255) completed a survey about perceived environmental quality, stress, weather, and restorativeness during their stay at the beach. We used linear models to evaluate the association between psychological restorativeness and social, environmental, and weather parameters. We also analyzed the nature of the association between temperature and restorativeness by viewing this relation as both linear and non-linear and by evaluating the differences in restorativeness between winter, springtime, and summer. The results suggested that the participants viewed the beach as psychologically restorative, especially during the winter season. We also found that the number of people that participants came with was negatively associated with perceived restorativeness. Finally, the results from the correlation analysis revealed that people are less stressed if they go to the beach more frequently

Structural pattern and functional correlations of the long bone diaphyses intracortical vascular system: investigation carried out with China ink perfusion and multiplanar analysis in the rabbit femur.

The intracortical vessel system of the rabbit femur has been studied after perfusion of the vascular tree with a water solution of dye (China ink) with multiplanar analysis. This method utilizes the full depth of field of the microscope objectives focusing different planes of the thick cortex. The microscopic observation even if restricted to a limited volume of cortex allowed to differentiate true 3-D nodes (54.5%) from the superimposition of vessels lying on different planes. The network model with elongated meshes preferentially oriented along the longitudinal axis of the diaphysis in his static configuration is not very different from the vascular anatomy depicted in the 2-D traditional models; however, the semi-quantitative morphometric analysis applied to the former supported the notion of a multidirectional microvascular network allowing change of flow according to the functional requirements. Other peculiar aspects not previously reported were cutting cone loops, blind-end and short-radius-bent vessels, and button-holes figures. The network design and node distribution were consistent with the straight trajectory of the secondary remodeling, with the proximal-to-distal and distal-to-proximal advancement directions of the cutting cones and with two main modes of node formation, namely bifurcation of the cutting cone and interception with pre-existing canals. The general organization of the network and its uninterrupted transformation during bone modeling and remodeling suggested a substantial plasticity of the intracortical vascular system capable to adapt itself to the changeable haemodynamic conditions

The shape modulation of osteoblast–osteocytetransformation and its correlationwith the fibrillar organization in secondary osteons: A SEM study employing the graded osmic maceration technique

Cortex fractured surface and graded osmic maceration techniques were used to study the secretory activity of osteoblasts, the transformation of osteoblast to osteocytes, and the structural organization of the matrix around the cells with scanning electron microscopy (SEM). A specialized membrane differentiation at the base of the cell was observed with finger-like, flattened processes which formed a diffuse meshwork. These findings suggested that this membrane differentiation below the cells had not only functioned in transporting collagen through the membrane but also in orienting the fibrils once assembled. Thin ramifications arose from the large and flat membrane foldings oriented perpendicular to the plane of the osteoblasts. This meshwork of fine filaments could not be visualized with SEM because they were obscured within the matrix substance. Their 3-D structure, however, should be similar to the canalicular system. The meshwork of large, flattened processes was no more evident in the cells which had completed their transformation into osteocytes

A peristomal plaque of sudden occurrence.

Koebner phenomenon regards the formation of a psoriatic lesion after a trauma, including tattoo, insect bite or other injuries. Although this manifestation is not specific for psoriasis, physicians should be aware because early recognition may be helpful in making the diagnosis when present

Scanning electron microscopy study of bone intracortical vessels using an injection and fractured surfaces technique

The intracortical canal/vessel systems of long bones are not yet completely understood in terms of their morphology and physiology, mainly because of the difficulty of injecting the small calibre vessels and cutting the calcified matrix. Here, we apply a novel method combining perfusion of the vessels and fracture of the cortical bone to enlighten the architecture of this system. The femurs of ten rabbits were perfused with a water-soluble dye (China ink) or alcoholic glycerol solution, and the fractured cortex specimens were then examined by scanning electron microscopy (SEM). The results document: (1) the fibrillar structure of the canal surfaces; (2) the perivascular environment with cellular components in different phases of incorporation within the bone matrix; (3) previously unreported filamentous structures on the outer surface of vessels, which could be interpreted as non-myelinic nerve fibres; (4) the inner organisation of the cutting cones. Although based exclusively on morphology, these observation have some relevance to increasing knowledge of bone circulation physiology in the cortical bone