Age-related differences in attentional cost associated with postural dual tasks: Increased recruitment of generic cognitive resources in older adults

Dual-task designs have been used widely to study the degree of automatic and controlled processing involved in postural stability of young and older adults. However, several unexplained discrepancies in the results weaken this literature. To resolve this problem, a careful selection of dual-task studies that met certain methodological criteria are considered with respect to reported interactions of age (young vs. older adults) × task (single vs. dual task) in stable and unstable postural conditions. Our review shows that older adults are able to perform a postural dual task as well as younger adults in stable conditions. However, when the complexity of the postural task is increased by dynamic conditions (surface and surround), performance in postural, concurrent, or both tasks is more affected in older relative to young adults. In light of neuroimaging studies and new conceptual frameworks, these results demonstrate an age-related increase of controlled processing of standing associated with greater intermittent adjustments.     

A comparative study of performance in simple and choice reaction time tasks between obese and healthy-weight children

This study investigated weight status related differences in executive functions and movement execution to determine whether or not childhood obesity is associated with impaired perceptual-motor function. Nineteen obese (OB) children (10 ♂ and 9 ♀, aged 6–12 years) and nineteen gender and age matched healthy-weight (HW) peers performed two computer-based reaction time tasks. For both the simple and four choice reaction time (SRT/CRT) task condition, absolute mean reaction time (RT) and movement time (MT) were determined and expressed as a percentage of total response time (RsT). During the SRT task, OB children were intrinsically slower than their HW peers as reflected by a significantly higher absolute RT, MT and RsT. In the CRT task, however, between-group differences were only present for RT and RsT, whereas absolute MT was comparable among OB and HW participants. As a result, the relative temporal structure of RsT significantly differed between BMI groups, with a greater RT percentage among the OB children. During the CRT condition, OB children probably await final decision-making with regard to the execution of their response movement, which then no longer needs to be adjusted. Our results therefore indicate the use of a more conservative strategy within the OB group, suggesting that childhood obesity is associated with impaired perceptual-motor function. Besides the widely accepted mechanical explanation, a better understanding of the mechanisms underlying OB children's motor incompetence is needed to set up appropriate interventions to tackle this deficit and indirectly address associated health-related problems.     

Preorthographical constraints on visual word recognition: evidence from a case study of developmental surface dyslexia

We investigated the visual word recognition ability of M.T., a young boy with surface dyslexia, by means of a paradigm that measures performance as a function of the eye fixation position within the word, known as the "viewing-position effect" paradigm. In well-achieving readers, the viewing-position effect is mainly determined by factors affecting letter visibility and by lexical constraints on word recognition. We further quantified M.T.'s sensory limitations on letter visibility by computing visual-span profiles - that is, the number of letters recognizable at a glance. Finally, in an ideal-observer's perspective, M.T.'s performance was compared with a parameter-free model combining M.T.'s letter visibility data with a simple lexical matching rule. The results showed that M.T. did not use the whole visual information available on letter identities to recognize words and that preorthographical factors constrained his word recognition performance. The results can be best accounted for by a reduction of the number of letters processed in parallel.     

Zaleplon and zolpidem objectively alleviate sleep disturbances in mountaineers at a 3,613 meter altitude

STUDY OBJECTIVES: To assess the effects of zolpidem and zaleplon on nocturnal sleep and breathing patterns at altitude, as well as on daytime attention, fatigue, and sleepiness. DESIGN: Double-blind, randomized, placebo-controlled, cross-over trial. SETTING: 3 day and night alpine expedition at 3,613 m altitude. PARTICIPANTS: 12 healthy male trekkers. PROCEDURE: One week spent at 1,000 m altitude (baseline control), followed by 3 periods of 3 consecutive treatment nights (N1-3) at altitude, to test 10 mg zolpidem, 10 mg zaleplon, and placebo given at 21:45. MEASURES: Sleep from EEG, actigraphy and sleep logs; overnight arterial saturation in oxygen (SpO2) from infrared oximetry; daytime attention, fatigue and sleepiness from a Digit Symbol Substitution Test, questionnaires, and sleep logs; acute mountain sickness (AMS) from the Lake Louise questionnaire. RESULTS: Compared to baseline control, sleep at altitude was significantly impaired in placebo subjects as shown by an increase in the amount of Wakefulness After Sleep Onset (WASO) from 17 +/- 8 to 36 +/- 13 min (P<0.05) and in arousals from 5 +/- 3 to 20 +/- 8 (P<0.01). Slow wave sleep (SWS) and stage 4 respectively decreased from 26.7% +/- 5.8% to 20.6% +/- 5.8% of total sleep time (TST) and from 18.2% +/- 5.2% to 12.4% +/- 3.1% TST (P<0.05 and P<0.001, respectively). Subjects also complained from a feeling of poor sleep quality combined with numerous 02 desaturation episodes. Subjective fatigue and AMS score were increased. Compared to placebo control, WASO decreased by approximately 6 min (P<0.05) and the sleep efficiency index increased by 2% (P<0.01) under zaleplon and zolpidem, while SWS and stage 4 respectively increased to 22.5% +/- 5.4% TST (P<0.05) and to 15.0% +/- 3.4% TST (P<0.0001) with zolpidem only; both drugs further improved sleep quality. No adverse effect on nighttime SpO2, daytime attention level, alertness, or mood was observed under either hypnotic. AMS was also found to be reduced under both medications. CONCLUSIONS: Both zolpidem and zaleplon have positive effects on sleep at altitude without adversely affecting respiration, attention, alertness, or mood. Hence, they may be safely used by climbers.     

Stereo vision enhances the learning of a catching skill

The aim of this study was to investigate the contribution of stereo vision to the acquisition of a natural interception task. Poor catchers with good (N = 8; Stereo+) and weak (N = 6; Stereo-) stereo vision participated in an intensive training program spread over 2 weeks, during which they caught over 1,400 tennis balls in a pre-post-retention design. While the Stereo+ group improved from a catching percentage of 18% to 59%, catchers in the Stereo- group did not significantly improve (from 10 to 31%), this progress being indifferent from a control group (N = 9) that did not practice at all. These results indicate that the development and use of of compensatory cues for depth perception in people with weak stereopsis is insufficient to successfully deal with interceptions under high temporal constraints, and that this disadvantage cannot be fully attenuated by specific and intensive training.     

How a plantar pressure-based,tongue-placed tactile biofeedback modifies postural control mechanisms during quiet standing

The purpose of the present study was to determine the effects of a plantar pressure-based, tongue-placed tactile biofeedback on postural control mechanisms during quiet standing. To this aim, 16 young healthy adults were asked to stand as immobile as possible with their eyes closed in two conditions of No-biofeedback and Biofeedback. Centre of foot pressure (CoP) displacements, recorded using a force platform, were used to compute the horizontal displacements of the vertical projection of the centre of gravity (CoG _v ) and those of the difference between the CoP and the vertical projection of the CoG (CoP-CoG _v ). Analysis of the CoP-CoG _v displacements showed larger root mean square (RMS) and mean power frequencies (MPF) in the Biofeedback than in the No-biofeedback condition. Stabilogram-diffusion analysis further showed a concomitant increased spatial and reduced temporal transition point co-ordinates at which the corrective processes were initiated and an increased persistent behaviour of the CoP-CoG _v displacements over the short-term region. Analysis of the CoG _v displacements showed decreased RMS and increased MPF in the Biofeedback relative to the No-biofeedback condition. Stabilogram-diffusion analysis further indicated that these effects mainly stem from reduced spatio-temporal transition point co-ordinates at which the corrective process involving CoG _v displacements is initiated and an increased anti-persistent behaviour of the CoG _v displacements over the long-term region. Altogether, the present findings suggest that the main way the plantar pressure-based, tongue-placed tactile biofeedback improves postural control during quiet standing is via both a reduction of the correction thresholds and an increased efficiency of the corrective mechanism involving the CoG _v displacements.     

Cross-sectional multicentre study on the cohort of all the French junior lecturers in general practice

Background: General practice became an academic discipline quite recently in many western countries. In France, junior lecturer work is specified in a three-part mandate: medical work in general practice, teaching in the university, and research. Since 2007, 130 junior lecturers have been appointed in general practice. The aim of the creation of junior lecturer status was to align general practice with other specialties and to develop research and education in primary care.

Objectives: To describe the healthcare, teaching and research undertaken by junior lecturers in general practice, practising in October 2014.

Methods: A cross-sectional multicentre study using an online self-administered questionnaire on the cohort composed of all the junior lecturers in general practice with open questions and the qualitative analysis of written verbatim accounts.

Results: Of the 95 junior lecturers practising at the date of the study, 75 (79%) responded; average age 32 years; gender ratio (F/M) 2.4:1. They spent five, two and three half-days per week respectively in healthcare, teaching and research. The healthcare activity was predominantly carried out in the community (73%). Thirty-nine per cent worked as part of a multi-professional team taking on 50 consultations per week. Most of the educational work involved lecturing and mentoring students specializing in general practice (median 86?hours per year). Research output increased during the fellowship. Research topics were varied and relevant to the disciplinary field.

Conclusion: During the fellowship, the balancing, and even the reinforcement, of healthcare and research contributions were accompanied by a significant investment in educational provision.     

Lateral unicondylar knee arthroplasty (UKA): Contemporary indications,surgical technique,and results

Unicompartmental femoro-tibial osteoarthritis usually affects the medial compartment of the knee, but in 10 %, the lateral compartment is primarily involved. Femoral osteotomy is attractive to avoid TKA in younger patients with low-grade unicompartmental osteoarthritis and a valgus deformity. However, only limited functional results can be expected for patients with Ahlback grade 2 or greater osteoarthritis. Moreover, because of previous skin incisions and hardware removal, TKA after femoral osteotomy remains a complex procedure with poor functional results. Unicompartmental knee arthroplasty for both the medial and the lateral compartments has been performed since the 1970s. In a patient with involvement of only one compartment, a medial or a lateral UKA can provide a quicker recovery and enhanced function when compared to TKA. In addition, it preserves bone stock and can be “easily” revised by a TKA. Technical improvements, combined with strict patient selection, have resulted in ten year survivorships greater than 90 %. However, lateral UKA is technically more challenging than medial UKA due to the lower number of indications, as well as the functional anatomy of the lateral compartment. The goals of this article are to present up-to-date information concerning indications, patients’ selection, surgical technique and results of lateral compartment UKA.