The role of working memory on dual-task cost during walking performance in childhood

This study examined the effect of a secondary motor task on walking ability, whether performance differed according to age and the possible relationship between cognitive abilities, specifically working memory, and dual-task costs in children with typical development. Fifty-three female children (mean age M = 10 \ub1 2 years), were divided into two different age groups: a young (7\u20139 years; n = 17) and an older group (10\u201313 years; n = 36). First, participants performed a Walking Test (WT) without additional tasks; afterward, they performed the same walking test while performing each of the following tasks: carrying (1) a glass of water, (2) a ball on a round tray and (3) the combination of both tasks (1) and (2). The Test of Memory and Learning were used to assess working memory. WTs under a dual-task condition generally produced worse results compared to a single-task condition [F(3,135) = 32.480, p < 0.001]. No age-related difference was observed [F(1,45) = 0.497, p = 0.485]. Age, digit forward and backward, facial memory, and paired recall accounted altogether for 28.6% of variance in dual-task ability during WT while carrying a glass of water and a ball on a round tray. Specifically, facial memory significantly accounted for the variance of DTC in WTWT (\u3b2 = 120.381, p = 0.016). Moreover, a trend toward a statistical significance was observed for digit forward (\u3b2 = 120.275, p = 0.085). Results underlined that regardless of the age, a dual-task performance might affect walking performance depending on the required secondary task. Moreover, our results showed the association between working memory skills and dual-task cost in walking abilit

Age-related differences of the gaze pattern in a realistic pedestrian traffic task

Laboratory studies suggest that the gaze pattern changes in older age, both in seated and in walking persons. Here we investigate the gaze pattern in a more complex and realistic scenario: walking in a virtual-reality shopping precinct. Seventeen young and sixteen older adults walked at their preferred speed on a treadmill driven by their leg movements, thus controlling the presentation of a virtual 3D world on a screen 130 cm ahead. The screen showed a shopping street with stationary and moving objects, and with six pedestrian traffic lights of whom three turned red upon approach. Gaze direction was registered by a video-based system. We found that each glance at a traffic light took longer in older than in young persons, and the sum of all glances at a traffic light was longer as well. In effect, older persons looked at the traffic light equally long throughout all three light phases, while young ones gradually increased their inspection of the traffic light as the green phase went on. The observed change of the gaze pattern in older age could represent a compensatory strategy to facilitate spatial orientation and/or movement preparation, or it could reflect a deficit of gaze disengagement. Future research should disambiguate these alternatives. In any case, the observed change is detrimental for seniors’ sensorimotor performance in everyday scenarios

Age Differences of Gaze Distribution during Pedestrian Walking in a Virtual-Reality Environment

The gaze pattern changes in old age, not only during artificial laboratory tasks but also during quasi-natural behavior. We have recently reported that older adults, walking in a virtual reality pedestrian precinct, spent longer time looking at pedestrian traffic lights than young adults did (Bock et al, 2015). We have interpreted this age-related change as a compensatory strategy, and we now analyze whether this strategy might be potentially hazardous in that it withdraws gaze from other regions that are critical for safe walking. Seventeen young and 16 older adults walked on a non-motorized treadmill linked to the 3D model of a pedestrian precint. The model was displayed on a monitor ahead, such that participants felt as if walking through the simulated world. Along their way, participants met a range of familiar objects such as pedestrian traffic lights, oncoming pedestrians and cats crossing their path. Eye position was recorded by a video-based system. We found that compared to young adults, older ones looked longer at regions of high behavioral relevance and less long at regions of low behavioral relevance. We conclude that looking longer at relevant regions might be a strategy for compensating central processing deficits, but this strategy may not pay off when an unexpected threat emerges in a seemingly irrelevant region

Report on the single-laboratory validation of a PCR-based Detection Method for Identification of Florigene™ IFD-25958-3 GM Carnation -Validation Report and Validated Method

In the context of the application for marketing submitted by Florigene Pty Ltd for a genetically modified carnation line (C/NL/09/01) IFD-25958-3, the European Union Reference Laboratory for GM Food and Feed (EU-RL GMFF) has carried out a single-laboratory validation to assess the performance of a polymerase chain reaction (PCR)-based detection method for detecting and identifying the carnation GM line IFD-25958-3. This report describes the results of tests carried out by the EU-RL GMFF on control samples provided by the method developer and according to the detection method described by the applicant. The taxon-specific method correctly detects the endogenous gene target in genomic DNA of a conventional carnation line (negative control) and in the genomic DNA of the GM carnation line; the same method can also detect the GM target DNA in IFD-25958-3 GM line (positive control) in the experimental conditions described in this report. The Limit of Detection (LOD) of the method has been estimated to be at least 50 copies for the taxon-specific gene and at least 100 copies for the GM insert, based on haploid genome copy number.JRC.I.3-Molecular Biology and Genomic