David Green

Depersonalisation/derealisation symptoms in vestibular disease

Background: Depersonalisation is a subjective experience of unreality and detachment from the self often accompanied by derealisation; the experience of the external world appearing to be strange or unreal. Feelings of unreality can be evoked by disorienting vestibular stimulation. Objective: To identify the prevalence of depersonalisation/derealisation symptoms in patients with peripheral vestibular disease and experimentally to induce these symptoms by vestibular stimulation. Methods: 121 healthy subjects and 50 patients with peripheral vestibular disease participated in the study. For comparison with the patients a subgroup of 50 age matched healthy subjects was delineated. All completed (1) an in-house health screening questionnaire; (2) the General Health Questionnaire (GHQ-12); (3) the 28-item depersonalisation/derealisation inventory of Cox and Swinson (2002). Experimental verification of “vestibular induced” depersonalisation/derealisation was assessed in 20 patients and 20 controls during caloric irrigation of the labyrinths. Results: The frequency and severity of symptoms in vestibular patients was significantly higher than in controls. In controls the most common experiences were of “déjà vu” and “difficulty in concentrating/attending”. In contrast, apart from dizziness, patients most frequently reported derealisation symptoms of “feel as if walking on shifting ground”, “body feels strange/not being in control of self”, and “feel ‘spacey’ or ‘spaced out’”. Items permitted discrimination between healthy subjects and vestibular patients in 92% of the cases. Apart from dizziness, caloric stimulation induced depersonalisation/derealisation symptoms which healthy subjects denied ever experiencing before, while patients reported that the symptoms were similar to those encountered during their disease. Conclusions: Depersonalisation/derealisation symptoms are both different in quality and more frequent under conditions of non-physiological vestibular stimulation. In vestibular disease, frequent experiences of derealisation may occur because distorted vestibular signals mismatch with the other sensory input to create an incoherent frame of spatial reference which makes the patient feel he or she is detached or separated from the world.

Back to the Moon: The scientific rationale for resuming lunar surface exploration

The lunar geological record has much to tell us about the earliest history of the Solar System, the origin and evolution of the Earth–Moon system, the geological evolution of rocky planets, and the near-Earth cosmic environment throughout Solar System history. In addition, the lunar surface offers outstanding opportunities for research in astronomy, astrobiology, fundamental physics, life sciences and human physiology and medicine. This paper provides an interdisciplinary review of outstanding lunar science objectives in all of these different areas. It is concluded that addressing them satisfactorily will require an end to the 40-year hiatus of lunar surface exploration, and the placing of new scientific instruments on, and the return of additional samples from, the surface of the Moon. Some of these objectives can be achieved robotically (e.g., through targeted sample return, the deployment of geophysical networks, and the placing of antennas on the lunar surface to form radio telescopes). However, in the longer term, most of these scientific objectives would benefit significantly from renewed human operations on the lunar surface. For these reasons it is highly desirable that current plans for renewed robotic surface exploration of the Moon are developed in the context of a future human lunar exploration programme, such as that proposed by the recently formulated Global Exploration Roadmap.

Depersonalisation/derealisation symptoms and updating orientation in patients with vestibular disease

Background: Patients with vestibular disease have an increased rate of reporting symptoms of depersonalisation/derealisation (DD) and similar symptoms can be provoked in healthy subjects during caloric vestibular stimulation. Objective: To assess the relationship between DD symptoms in patients with peripheral vestibular disease and their ability to update orientation in the environment. Methods: Sixty healthy subjects and 50 patients with peripheral vestibular disease completed a DD questionnaire (Cox and Swinson, 2002) and a General Health Questionnaire (GHQ)-12 (Goldberg and Williams, 1988). This was followed by a test of updating spatial orientation in which subjects were exposed to 10 manually driven whole body rotations of 45°, 90° or 135° in a square room, which contained distinctive features on the walls, in such a way that the features and corners subtended 45° with respect to the subject. After each rotation subjects reported which wall or corner they were facing. Estimation error was calculated by subtracting the reported rotation from the actual rotation. Results: DD scores were significantly higher in vestibular patients than in healthy subjects (p<0.05, t test). In patients, the lowest symptom scores and the lowest estimation errors were found in those with a unilateral canal paresis without balance symptoms whereas the highest scores and largest estimation errors were found in those with bilateral vestibular loss (p<0.05, ANOVA). Across all patients, DD scores were related to estimation errors (adjusted r2 = 0.25, p<0.05, ANCOVA). Conclusions: Patients with peripheral vestibular disease have a deficit in the ability to update orientation on the environment and a high prevalence of DD symptoms, which may imply a high order effect of the vestibular impairment. Derealisation symptoms in vestibular disease may be a consequence of a sensory mismatch between disordered vestibular input and other sensory signals of orientation.

Symptomatic Recovery in Miller Fisher Syndrome Parallels Vestibular–Perceptual and not Vestibular–Ocular Reflex Function

Unpleasant visual symptoms including oscillopsia and dizziness may occur when there is unexpected motion of the visual world across the subjects retina (“retinal slip”) as in an acute spontaneous nystagmus or on head movement with an acute ophthalmoplegia. In contrast, subjects with chronic ocular dysmotility, e.g., congenital nystagmus or chronic progressive external ophthalmoplegia, are typically symptom free. The adaptive processes that render chronic patients asymptomatic are obscure but may include a suppression of oscillopsia perception as well as an increased tolerance to perceived oscillopsia. Such chronic asymptomatic patients display an attenuation of vestibular-mediated angular velocity perception, implying a possible contributory role in the adaptive process. In order to assess causality between symptoms, signs (i.e., eye movements), and vestibular–perceptual function, we prospectively assessed symptom ratings and ocular-motor and perceptual vestibular function, in a patient with acute but transient ophthalmoplegia due to Miller Fisher Syndrome (as a model of visuo-vestibular adaptation). The data show that perceptual measures of vestibular function display a significant attenuation as compared to ocular-motor measures during the acute, symptomatic period. Perhaps significantly, both symptomatic recovery and normalization of vestibular–perceptual function were delayed and then occurred in a parallel fashion. This is the first report showing that symptomatic recovery of visuo-vestibular symptoms is better paralleled by vestibular–perceptual testing than vestibular–ocular reflex (VOR) measures. The findings may have implications for the understanding of patients with chronic vestibular symptoms where VOR testing is often unhelpful.

Postural prioritization is differentially altered in healthy older compared to younger adults during visual and auditory coded spatial multitasking

Many daily activities require appropriate allocation of attention between postural and cognitive tasks (i.e. dual-tasking) to be carried out effectively. Processing multiple streams of spatial information is important for everyday tasks such as road crossing. Fifteen community-dwelling healthy older (mean age=78.3, male=1) and twenty younger adults (mean age=25.3, male=6) completed a novel bimodal spatial multi-task test providing contextually similar spatial information via separate sensory modalities to investigate effects on postural prioritization. Two tasks, a temporally random visually coded spatial step navigation task (VS) and a regular auditory-coded spatial congruency task (AS) were performed independently (single task) and in combination (multi-task). Response time, accuracy and dual-task costs (% change in multi-task condition) were determined. Results showed a significant 3-way interaction between task type (VS vs. AS), complexity (single vs. multi) and age group for both response time (p ≤ 0.01) and response accuracy (p ≤ 0.05) with older adults performing significantly worse than younger adults. Dual-task costs were significantly greater for older compared to younger adults in the VS step task for both response time (p ≤ 0.01) and accuracy (p ≤ 0.05) indicating prioritization of the AS over the VS stepping task in older adults. Younger adults display greater AS task response time dual task costs compared to older adults (p ≤ 0.05) indicating VS task prioritization in agreement with the posture first strategy. Findings suggest that novel dual modality spatial testing may lead to adoption of postural strategies that deviate from posture first, particularly in older people. Adoption of previously unreported postural prioritization strategies may influence balance control in older people.

Effect of Orthostasis on Endothelial Function: A Gender Comparative Study

As the vascular endothelium has multiple functions, including regulation of vascular tone, it may play a role in the pathophysiology of orthostatic intolerance. We investigated the effect of orthostasis on endothelial function using EndoPAT®, a non-invasive and user-independent method, and across gender. As sex steroid hormones are known to affect endothelial function, this study examined the potential effect of these hormones on the endothelial response to orthostasis by including females at different phases of the menstrual cycle (follicular and luteal—where the hormone balance differs), and females taking an oral contraceptive. A total of 31 subjects took part in this study (11 males, 11 females having normal menstrual cycles and 9 females taking oral contraceptive). Each subject made two visits for testing; in the case of females having normal menstrual cycles the first session was conducted either 1–7 (follicular) or 14–21 days (luteal) after the start of menstruation, and the second session two weeks later, i.e., during the other phase, respectively. Endothelial function was assessed at baseline and following a 20-min orthostatic challenge (active standing). The EndoPAT® index increased from 1.71 ± 0.09 (mean ± SEM) at baseline to 2.07 ± 0.09 following orthostasis in females (p<0.001). In males, the index increased from 1.60 ± 0.08 to 1.94 ± 0.13 following orthostasis (p<0.001). There were no significant differences, however, in the endothelial response to orthostasis between females and males, menstrual cycle phases and the usage of oral contraceptive. Our results suggest an increased vasodilatatory endothelial response following orthostasis in both females and males. The effect of gender and sex hormones on the endothelial response to orthostasis appears limited. Further studies are needed to determine the potential role of this post orthostasis endothelial response in the pathophysiology of orthostatic intolerance.

Effect of postural changes on cardiovascular parameters across gender

Introduction: We investigated the effect of postural changes on various cardiovascular parameters across gender. Twenty-eight healthy subjects (16 male, 12 female) were observed at rest (supine) and subjected to 3 interventions; head-down tilt (HDT), HDT with lower body negative pressure (HDT+ LBNP at −30 mm Hg), and head-up tilt (HUT), each for 10 minutes separated by a 10 minutes recovery period. Methods: Measurements were recorded for heart rate (HR), standard deviation of the normal-to-normal intervals, root mean square of successive differences between the normal-to-normal intervals, heart rate variability-low frequency (LFRRI), heart rate variability-high frequency (HFRRI), low frequency/high frequency ratio (LFRRI/HFRRI), systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), total peripheral resistance index (TPRI), stroke index (SI), cardiac index (CI), index of contractility (IC), left ventricular work index, and left ventricular ejection time. Results: Across all cardiovascular parameters, there was a significant main effect of the intervention applied but there was no significant main effect of gender across all parameters. Conclusions: The results suggest that there are no specific gender differences in regards to the measured variables under the conditions of this study. Furthermore, these results suggest that in healthy subjects, there appears to be evidence that LBNP partially elicits similar cardiovascular responses to HUT, which supports the use of LBNP as an intervention to counteract the effects of central hypovolemia.

Wide-Pulse Electrical Stimulation to an Intrinsic Foot Muscle Induces Acute Functional Changes in Forefoot–Rearfoot Coupling Behaviour during Walking

Interventions for strengthening intrinsic foot muscles may be beneficial for rehabilitation from overuse injuries. In this study the acute effects of high-frequency, low-intensity wide-pulse electrical stimulation (WPS) over an intrinsic muscle on subsequent foot function during walking was assessed in healthy participants. WPS was delivered to the m. abductor hallucis (m.AH) of the non-dominant foot during relaxed standing. 3-dimensional forefoot (FF)--rearfoot (RF) coordination was quantified with a vector coding technique within separate periods of the stance phase to study WPS functional effects on foot motion. 4 types of coordinative strategies between the FF and RF were interpreted and compared PRE-to-POST-WPS for both the experimental and control feet. Bilateral electromyography (EMG) from m.AH was analysed during the intervention period for evidence of acute neuromuscular adaptation. The results showed that WPS significantly modulated FF-RF coordination during mid-stance, indicative of a more stable foot. Specifically, a statistically significant increase in FF eversion with concomitant RF inversion in the frontal plane and RF-dominated adduction in the transverse plane was observed. Subject-specific increases in post-stimulus m.AH EMG activation were observed but this was not reflected in an overall group effect. It is concluded that the structural integrity of the foot during walking is enhanced following an acute session of WPS and that this mechanical effect is most likely due to stimulation induced post-tetanic potentiation of synaptic transmission.

Banking supervision in Europe and economic and monetary union

Abstract The Treaty on European Union assigns responsibility for monetary policy to the European tier of government. This has major implications for the regulation and prudential supervision of banks. However, the assignment of these responsibilities was left ambiguous by the Treaty. As banking is a critically important part of the economic infrastructure, this is a matter of significant public policy concern. This article outlines the three major identifiable approaches which may be taken towards the future regulation and supervision of banking in the European Union (EU). A discussion of the reasons for such regulation and prudential supervision is followed by an assessment of recent relevant experience. The very substantial economic costs of poorly designed regulation and inadequate supervision arc illustrated. After a detailed discussion of the case for increased involvement of the EU tier of government in this sphere, the article concludes that the case for such a development is becoming increasingly ...

The effect of the gravity loading countermeasure skinsuit upon movement and strength.

Abstract Carvil, PA, Attias, J, Evetts, SN, Waldie, JM, and Green, DA. The effect of the gravity loading countermeasure skinsuit upon movement and strength. J Strength Cond Res 31(1): 154–161, 2017—Effective countermeasures against musculoskeletal deconditioning induced by microgravity and disuse are required. A simple alternative to provision of artificial gravity by centrifugation is compressive axial loading. The Russian “Pingvin” suit was the first wearable suit to apply this concept using bungee cords tethered around the shoulders and feet. However, poor loading characteristics and severe thermal and movement discomfort were reported. The gravity loading countermeasure skinsuit (GLCS) uses a bidirectional weave to generate staged axial loading from shoulders to feet, better mimicking how Earths gravity induces progressive loading head to foot. The Mk III GLCSs loading was evaluated and tolerability assessed during maximal joint motion, ambulation, and selected strength exercises. Eight subjects (5 male and 3 female; 28 ± 3 years; 179 ± 0.1 cm and 74.8 ± 2.9 kg), having given written informed consent, had an Mk III GLCS individually tailored. Axial loading imparted, body height, joint range of motion (ROM), ambulation, and strength tests (12 repetition maximum) were performed in the GLCS and gym attire, with subjective (rating of perceived exertion, thermal comfort, movement discomfort and body control) ratings recorded throughout. Gravity loading countermeasure skinsuit provided significant axial loading when standing but significantly reduced knee (−13°), spinal (−28°) and shoulder flexion/extension ROM (−34°/−13°), in addition to Sit and Reach (−12.8 cm). No thermal issues were reported but there was an increase in subjective discomfort. Gravity loading countermeasure skinsuit did not significantly impede strength exercise, with the exception of shoulder press. The GLCS (Mk III) demonstrates potential as a countermeasure by providing tolerable, static axial loading. Furthermore, it may serve as an elasticlike strength exercise adjunct, which may have utility as a rehabilitation modality after further design refinement.