Motor-based bodily self is selectively impaired in eating disorders

BACKGROUND: Body representation disturbances in body schema (i.e. unconscious sensorimotor body representations for action) have been frequently reported in eating disorders. Recently, it has been proposed that body schema relies on adequate functioning of the motor system, which is strongly implicated in discriminating between one’s own and someone else’s body. The present study aimed to investigate the motor-based bodily self in eating disorders and controls, in order to examine the role of the motor system in body representation disturbances at the body schema level. METHODS: Female outpatients diagnosed with eating disorders (N = 15), and healthy controls (N = 18) underwent a hand laterality task, in which their own (self-stimuli) and someone else’s hands (other-stimuli) were displayed at different orientations. Participants had to mentally rotate their own hand in order to provide a laterality judgement. Group differences in motor-based bodily self-recognition—i.e. whether a general advantage occurred when implicitly processing self- vs. other-stimuli − were evaluated, by analyzing response times and accuracy by means of mixed ANOVAs. RESULTS: Patients with eating disorders did not show a temporal advantage when mentally rotating self-stimuli compared to other-stimuli, as opposed to controls (F(1, 31) = 5.6, p = 0.02; eating disorders-other = 1092 ±256 msec, eating disorders-self = 1097±254 msec; healthy controls-other = 1239±233 msec, healthy controls -self = 1192±232 msec). CONCLUSIONS: This study provides initial indication that high-level motor functions might be compromised as part of body schema disturbances in eating disorders. Further larger investigations are required to test motor system abnormalities in the context of body schema disturbance in eating disorders

A kinematic examination of dual-route processing for action imitation

The dual-route model of imitation suggests that meaningful and meaningless actions are processed through either an indirect or direct route, respectively. Evidence indicates that the direct route is more cognitively demanding, since it relies on mapping visuospatial properties of the observed action on to a performed one. These cognitive demands might negatively influence reaction time and accuracy for actions performed following a meaningless action under time constraints. However, how meaningful and meaningless action imitation processing is reflected in movement kinematics is not yet clear. We wanted to confirm whether meaningless action performance incurs a reaction time cost, whether the cost is reflected in kinematics, and, more generally, to examine kinematic markers of emblematic meaningful and meaningless action imitation. We examined participants’ reaction time and wrist movements when they imitated emblematic meaningful or matched meaningless gestures in either blocks of the same action type, or mixed blocks. Meaningless actions were associated with a greater correction period at the end of the movement, possibly reflecting a strategy designed to ensure accurate completion for less familiar actions under time constraints. Furthermore, in mixed blocks, trials following meaningless actions had a significantly increased reaction time, supporting previous claims that route selection for action imitation may be stimulus-driven. However, there was only convincing evidence for this effect with an interval of ~2948ms, but not ~3573ms or ~2553ms, between movements. Future work motion-tracking the entire hand to assess imitation accuracy, and more closely examining the influence of duration between movements, may help to explain these effects

Examining ecological validity in social interaction: problems of visual fidelity, gaze, and social potential

Social interaction is an essential part of the human experience, and much work has been done to study it. However, several common approaches to examining social interactions in psychological research may inadvertently either unnaturally constrain the observed behaviour by causing it to deviate from naturalistic performance, or introduce unwanted sources of variance. In particular, these sources are the differences between naturalistic and experimental behaviour that occur from changes in visual fidelity (quality of the observed stimuli), gaze (whether it is controlled for in the stimuli), and social potential (potential for the stimuli to provide actual interaction). We expand on these possible sources of extraneous variance and why they may be important. We review the ways in which experimenters have developed novel designs to remove these sources of extraneous variance. New experimental designs using a ‘two-person’ approach are argued to be one of the most effective ways to develop more ecologically valid measures of social interaction, and we suggest that future work on social interaction should use these designs wherever possible

Bone histology provides insights into the life history mechanisms underlying dwarfing in hipparionins

Size shifts may be a by-product of alterations in life history traits driven by natural selection. Although this approach has been proposed for islands, it has not yet been explored in continental faunas. The trends towards size decrease experienced by some hipparionins constitute a good case study for the application of a life history framework to understand the size shifts on the continent. Here, we analysed bone microstructure to reconstruct the growth of some different-sized hipparionins from Greece and Spain. The two dwarfed lineages studied show different growth strategies. The Greek hipparions ceased growth early at a small size thus advancing maturity, whilst the slower-growing Spanish hipparion matured later at a small size. Based on predictive life history models, we suggest that high adult mortality was the likely selective force behind early maturity and associated size decrease in the Greek lineage. Conversely, we infer that resource limitation accompanied by high juvenile mortality triggered decrease in growth rate and a relative late maturity in the Spanish lineage. Our results provide evidence that different selective pressures can precipitate different changes in life history that lead to similar size shifts

Detecting temporal reversals in human locomotion

An experiment investigated the ability by human observers to detect temporal reversals in dynamic displays of human locomotion. We video-taped the lower portion of the body of actors walking at their preferred speed either in the normal, forward direction (FW) or in the backward direction (BW). The videos were presented in a random order either as recorded (N) or in reverse (R). In one session, we presented both normal and time-reversed stimuli in the original upright orientation. In a second session, the stimuli were rotated by 180° around the horizontal axis. Observers were informed that the real recorded movement was either forward or backward and were asked to decide whether or not the movement had been time-reversed prior to the presentation. Although the kinematics of forward and backward human locomotion is quite similar, the detection of temporal reversals followed a consistent pattern showing a good accuracy in condition FW-N and a reduced but still above-chance performance in condition BW-R (by design, in both conditions actors appeared to walk forward). Performance was instead at chance level in the other two conditions where the apparent direction of the movement was backward. Inverting the spatial orientation of the stimuli reduced but did not suppress the ability to detect temporal reversals in the two conditions with apparent forward direction of movement. It is argued that implicit motor competence is at least in part instrumental for extracting the subtle discriminal information from the stimuli

Type I lamellar ichthyosis improved by tazarotene 0.1% gel

The efficacy of tazarotene 0.1% gel in a 30-year-old woman with type I lamellar ichthyosis is reported. The drug was applied to 15% of the total body surface area as follows: once daily for 2 weeks, three times a week for further 2 weeks, followed by a once weekly maintenance application. During the first week of treatment there was partial improvement obtained and in the next 14 days further reduction of scaling within the tazarotene-treated areas was observed. After 4 months of maintenance application, there was a marked overall improvement in the treated areas. Side-effects consisted only of mild pruritus, slight burning and irritation. In essence, the therapeutic benefit obtained was comparable with that of systemic retinoids but without the adverse systemic side-effects. As noted in other reports, tazarotene 0.1% gel seems to be a valuable and safe therapeutic option for this severe genodermatosis

High-dose Intravenous Immunoglobulin for Severe Drug Reactions: Efficacy in Toxic Epidermal Necrolysis

High-dose intravenous immunoglobulin has been proposed as an alternative treatment for several immuno-mediated inflammatory skin diseases, usually at a dosage of 1-2 g/kg. We describe the treatment of 10 patients affected by toxic epidermal necrolysis using 400 mg/kg per day on 5 consecutive days - a schedule that is lower than previously reported schedules. According to the SCORTEN, the earlier predicted mortality rate was 35%. After high-dose intravenous immunoglobulin therapy, a mortality rate of 10% and a survival rate of 90% were reached. In particular, nine patients showed a dramatic improvement already after one course of infusion started at an early stage of the disease. It is our experience, and that of others, that high-dose intravenous immunoglobulin can be considered the drug of first choice for toxic epidermal necrolysis, one of the most severe life-threatening dermatological conditions, and a valid alternative therapy for different long-standing chronic dermatological diseases. This therapy can also be effective in avoiding high steroid dosages and consequently steroid-related or immunosuppressive-related side effects. It is therefore reasonable to propose high-dose intravenous immunoglobulin treatment as a valuable therapeutic tool for dermatologists