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Predictable somatosensory feedback leads to a reduction in tactile sensitivity. This phenomenon, called tactile suppression , relies on a mechanism that uses an efference copy of motor commands to help select relevant aspects of incoming sensory signals. We investigated whether tactile suppression is modulated by (a) the task-relevancy of the predicted consequences of movement and (b) the intensity of related somatosensory feedback signals. Participants reached to a target region in the air in front of a screen; visual or tactile feedback indicated the reach was successful. Furthermore, tactile feedback intensity (strong vs. weak) varied across two groups of participants. We measured tactile suppression by comparing detection thresholds for a probing vibration applied to the finger either early or late during reach and at rest. As expected, we found an overall decrease in late-reach suppression, as no touch was involved at the end of the reach. We observed an increase in the degree of tactile suppression when strong tactile feedback was given at the end of the reach, compared to when weak tactile feedback or visual feedback was given. Our results suggest that the extent of tactile suppression can be adapted to different demands of somatosensory processing. Downregulation of this mechanism is invoked only when the consequences of missing a weak movement sequence are severe for the task. The decisive factor for the presence of tactile suppression seems not to be the predicted action effect as such, but the need to detect and process anticipated feedback signals occurring during movement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Beyvers, Fraser and Fiehler.)

Introduction: Embodiment involves experiencing ownership over our body and localizing it in space and is informed by multiple senses (visual, proprioceptive and tactile). Evidence suggests that embodiment and multisensory integration may change with older age. The Virtual Hand Illusion (VHI) has been used to investigate multisensory contributions to embodiment, but has never been evaluated in older adults. Spatio-temporal factors unique to virtual environments may differentially affect the embodied perceptions of older and younger adults., Methods: Twenty-one younger (18-35 years) and 19 older (65+ years) adults completed the VHI paradigm. Body localization was measured at baseline and again, with subjective ownership ratings, following synchronous and asynchronous visual-tactile interactions., Results: Higher ownership ratings were observed in the synchronous relative to the asynchronous condition, but no effects on localization/drift were found. No age differences were observed. Localization accuracy was biased in both age groups when the virtual hand was aligned with the real hand, indicating a visual mislocalization of the virtual hand., Conclusions: No age-related differences in the VHI were observed. Mislocalization of the hand in VR occurred for both groups, even when congruent and aligned; however, tactile feedback reduced localization biases. Our results expand the current understanding of age-related changes in multisensory embodiment within virtual environments., Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2021.)

Sensitivity to touch is reduced during movement; this tactile suppression is likely the result of a mechanism that suppresses self-generated movement consequences. We sought to determine whether tactile suppression is modulated by naturally evoked changes in movement speed driven by task precision demands (Exp.1), and by changes in predicted movement consequences (Exp.2). We measured suppression by comparing detection thresholds for a vibration applied to the finger during reach and at rest. In Experiment 1 we varied reach target size to create a speed-accuracy tradeoff, where participants decelerated more to smaller targets to accurately hit them. We theorized that the reduction in late-reach speed associated with higher precision demands might lead to a reduction in late-reach suppression, consistent with the literature showing a positive relationship between speed and suppression. Contrary to our hypothesis, we found suppression increased towards the end of the reach in all conditions, despite a significant decrease in reaching speed. We postulated this might be a de-emphasizing of the predicted tactile feedback associated with tapping the target. To test this, in Experiment 2 we paired a vibration consequence with a target of a certain colour. We found an increase in late-reach suppression for this target compared to a target of another colour with no associated consequence. Our results indicate that tactile suppression is temporally sensitive and increases as predicted consequences become more likely. We propose the positive correlation between movement speed and suppression previously reported may be driven by the predicted somatosensory consequences associated with increased movement speed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: Perceived upright depends on three main factors: vision, graviception, and the internal representation of the long axis of the body. We assessed the relative contributions of these factors in individuals with sub-acute and chronic stroke and controls using a novel tool; the Oriented Character Recognition Test (OCHART). We also considered whether individuals who displayed active pushing or had a history of pushing behaviours had different weightings than those with no signs of pushing., Method: Three participants experienced a stroke 6 months prior: eight with a history of pushing. In total, 12 participants served as healthy aged-matched controls. Visual and graviceptive cues were dissociated by orienting the visual background left, right, or upright relative to the body, or by orienting the body left, right, or upright relative to gravity. A three-vector model was used to quantify the weightings of vision, graviception, and the body to the perceptual upright., Results: The control group showed weightings of 13% vision, 25% graviception, and 62% body. Some individuals with stroke showed a similar pattern; others, particularly those with recent stroke, showed different patterns, for example, being unaffected by one of the three factors. The participant with active pushing behaviour displayed an ipsilesional perceptual bias (>30°) and was not affected by visual cues to upright., Conclusion: The results of OCHART may be used to quantify the weightings of multisensory inputs in individuals post-stroke and may help characterize perceptual sources of pushing behaviours.

In the absence of visual feedback, the perceived orientation of the fingers is systematically biased. In right-handers these biases are asymmetrical between the left and right hands in the horizontal plane and may reflect common functional postures for the two hands. Here we compared finger orientation perception in right- and left-handed participants for both hands, across various hand positions in the horizontal plane. Participants rotated a white line on a screen optically superimposed over their hand to indicate the perceived position of the finger that was rotated to one of seven orientations with the hand either aligned with the body midline, aligned with the shoulder, or displaced by twice the shoulder-to-midline distance from the midline. We replicated the asymmetric pattern of biases previously reported in right-handed participants (left hand biased towards an orientation ~30° inward, right hand ~10° inward). However, no such asymmetry was found for left-handers, suggesting left-handers may use different strategies when mapping proprioception to body or space coordinates and/or have less specialization of function between the hands. Both groups' responses rotated further outward as distance of the hand from the body midline increased, consistent with other research showing spatial orientation estimates diverge outward in the periphery. Finally, for right-handers, precision of responses was best when the hand was aligned with the shoulder compared to the other two conditions. These results highlight the unique role of hand dominance and hand position in perception of finger orientation, and provide insight into the proprioceptive position sense of the upper limbs.

In the absence of visual feedback, the perceived position of the hands is systematically biased towards the plausible manual task space. Here we tested whether perceived orientation of the finger is similarly misperceived in right-handed individuals. Participants' index fingers were passively rotated about the middle joint to a range of test angles, either in the frontoparallel plane (Experiment 1) or the horizontal plane (Experiment 2); they reported perceived orientation of the finger by rotating a visual line presented on a screen optically superimposed on the location of their unseen finger. Perceived finger orientations were biased towards positions that varied across hands and planes. Both hands were biased towards 10° inward in the frontoparallel plane and, in the horizontal plane, the left hand was biased towards 25° inward, whereas the right hand was biased towards 2° inwards. In a third experiment, participants reported finger orientation with respect to non-visual targets: gravitational vertical or straight ahead. Biases in perceived finger orientation to non-visual targets were similar to those found in the visual line task. The asymmetrical nature of biases across hands and planes reflects the typical orientation of the hands while working and supports the theory of a functional rather than anatomical representation of the fingers and hands in space.

The subjective visual vertical (SVV) and the subjective haptic vertical (SHV) both claim to probe the underlying perception of gravity. However, when the body is roll tilted these two measures evoke different patterns of errors with SVV generally becoming biased towards the body (A-effect, named for its discoverer, Hermann Rudolph Aubert) and SHV remaining accurate or becoming biased away from the body (E-effect, short for Entgegengesetzt-effect, meaning "opposite", i.e., opposite to the A-effect). We compared the two methods in a series of five experiments and provide evidence that the two measures access two different but related estimates of gravitational vertical. Experiment 1 compared SVV and SHV across three levels of whole-body tilt and found that SVV showed an A-effect at larger tilts while SHV was accurate. Experiment 2 found that tilting either the head or the trunk independently produced an A-effect in SVV while SHV remained accurate when the head was tilted on an upright body but showed an A-effect when the body was tilted below an upright head. Experiment 3 repeated these head/body configurations in the presence of vestibular noise induced by using disruptive galvanic vestibular stimulation (dGVS). dGVS abolished both SVV and SHV A-effects while evoking a massive E-effect in the SHV head tilt condition. Experiments 4 and 5 show that SVV and SHV do not combine in an optimally statistical fashion, but when vibration is applied to the dorsal neck muscles, integration becomes optimal. Overall our results suggest that SVV and SHV access distinct underlying gravity percepts based primarily on head and body position information respectively, consistent with a model proposed by Clemens and colleagues.

Incorporating the fact that the senses are embodied is necessary for an organism to interpret sensory information. Before a unified perception of the world can be formed, sensory signals must be processed with reference to body representation. The various attributes of the body such as shape, proportion, posture, and movement can be both derived from the various sensory systems and can affect perception of the world (including the body itself). In this review we examine the relationships between sensory and motor information, body representations, and perceptions of the world and the body. We provide several examples of how the body affects perception (including but not limited to body perception). First we show that body orientation effects visual distance perception and object orientation. Also, visual-auditory crossmodal-correspondences depend on the orientation of the body: audio "high" frequencies correspond to a visual "up" defined by both gravity and body coordinates. Next, we show that perceived locations of touch is affected by the orientation of the head and eyes on the body, suggesting a visual component to coding body locations. Additionally, the reference-frame used for coding touch locations seems to depend on whether gaze is static or moved relative to the body during the tactile task. The perceived attributes of the body such as body size, affect tactile perception even at the level of detection thresholds and two-point discrimination. Next, long-range tactile masking provides clues to the posture of the body in a canonical body schema. Finally, ownership of seen body parts depends on the orientation and perspective of the body part in view. Together, all of these findings demonstrate how sensory and motor information, body representations, and perceptions (of the body and the world) are interdependent.

Inconsistent communication during intershift report had resulted in loss of vital information. This project was developed to implement the use of nursing care plans for intershift report on a 25-bed school-age unit. A review of literature showed an absence of any systematic method for intershift report. Classes that included a 20-minute video, written guidelines, and discussion were used to promote the use of nursing care plans for intershift report. A questionnaire was administered to the nursing staff 3 weeks after class to evaluate the project. The evaluation of use of the care plans indicated: (a) a more focused intershift report; (b) an improved structure for report, including important information about the child and family; (c) increased communication; (d) more practical up-to-date care plans; and (e) increased professionalism and collaboration.

We report the radiographic and computed tomographic findings in an asymptomatic patient who had a Haemophilus influenzae lung abscess. The diagnosis was made by Gram's staining and culture of abscess material obtained by transthoracic needle aspiration. The radiographic abnormalities cleared after specific antimicrobial therapy.