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Extensive practice can significantly reduce dual-task costs (i.e., impaired performance under dual-task conditions compared with single-task conditions) and, thus, improve dual-task performance. Among others, these practice effects are attributed to an optimization of executive function skills that are necessary for coordinating tasks that overlap in time. In detail, this optimization of dual-task coordination skills is associated with the efficient instantiation of component task information in working memory at the onset of a dual-task trial. In the present paper, we review empirical findings on three critical predictions of this memory hypothesis. These predictions concern (1) the preconditions for the acquisition and transfer of coordination skills due to practice, (2) the role of task complexity and difficulty, and (3) the impact of age-related decline in working memory capacity on dual-task optimization.

IntroductionCoronavirus disease (COVID-19) was associated with cognitive alterations affecting everyday life activities. These need input integration of both motor and cognitive systems. The study aim is to evaluate cognitive-motor interference phenomenon in previously independent patients with mild-to-moderate COVID-19 (PwMCOVID-19) compared with healthy controls (HC), through dual-task (DT) paradigm.MethodsPwMCOVID-19 were included if being independent at home, had no previous referred cognitive impairment, mechanical ventilation or oxygen need. They were assessed at admission and after 6 months with a motor-cognitive DT test (counting backward by twos while walking 2 min). HC were enrolled as control group. Differences between single-task (ST) and DT performance, DT effect (DTE) and task prioritization amongst groups and during time points were analyzed.ResultsOne-hundred PwMCOVID-19 [mean age=67.32(12.08) years; 53 M/47 F] and 39 HC [mean age=63.11(9.90) years; 20 M/19 F] were recruited. Upon T0, PwMCOVID-19 showed lower cognitive and motor DT performances than ST and HC. Mutual interference pattern was predominant in PwMCOVID-19. At T1, 41 PwMCOVID-19 were examined [mean age=64.85(10.75); 22 M/19 F]. They had a worse DT performance compared to ST, although DT improved at T1. A stronger cognitive ST-DT difference was present at T0, compared to ST-DT difference at T1, while motor ST-DT difference was unchanged over time in PwCOVID-19.ConclusionIn PwMCOVID-19, there is an impairment of DT counting while walking at baseline and after 6 months from hospitalization, with a more pronounced DT mutual interference pattern at T0. After 6 months, the motor and cognitive ST and DT performances ameliorated, not reaching the HC level.

The application of dual-task walking paradigms for gait assessment in stroke patients is critical, where varying concurrent tasks may elicit distinct gait patterns of dual-task interference. This study assessed the acute effects of different types of dual tasks on gait in stroke patients during task performance, informing occupational, and physical therapists about care recommendations to prevent patients from falling and improve their balance function in daily life. A total of 19 stroke patients (52.7 ± 6.9 years old) performed the walking-only and dual-task walking (motor, arithmetic and speech) task test while a 3D motion capture system measured the gait parameters (the gait spatial-temporal parameters, sagittal angle of lower-limb joints, gait parameter variability and dual-task cost). One-way repeated measures ANOVA was used to test the effects of the above four walking conditions on gait parameters. Arithmetic task and speech task interference can affect the gait of stroke patients ( < 0.05). Arithmetic task interference has the greatest impact on step speed, cadence, single support phase, hip joint range in support period and has the greatest dual-task cost, speech task interference has the greatest impact on cadence coefficient of variation ( < 0.05). The motor task was not significantly different from walking-only ( >0.05). Both arithmetic and speech tasks have a great impact on gait in stroke patients. Faced with cognitive interference, stroke patients spontaneously adopted a \"cautious gait\" walking pattern. In future rehabilitation training, diversity of task types is critical for gait rehabilitation training based on the walking ability of the patients.

Nowadays, gait assessment in the real life environment is gaining more attention. Therefore, it is desirable to know how some factors, such as surfaces (natural, artificial) or dual-tasking, influence real life gait pattern. The aim of this study was to assess gait variability and gait complexity during single and dual-task walking on different surfaces in an outdoor environment. Twenty-nine healthy young adults aged 23.31 ± 2.26 years (18 females, 11 males) walked at their preferred walking speed on three different surfaces (asphalt, cobbles, grass) in single-task and in two dual-task conditions (manual task—carrying a cup filled with water, cognitive task—subtracting the number 7). A triaxial inertial sensor attached to the lower trunk was used to record trunk acceleration during gait. From 15 strides, sample entropy (SampEn) as an indicator of gait complexity and root mean square (RMS) as an indicator of gait variability were computed. The findings demonstrate that in an outdoor environment, the surfaces significantly impacted only gait variability, not complexity, and that the tasks affected both gait variability and complexity in young healthy adults.

Everyday activities like walking and talking can put an older adult at risk for a fall if they have difficulty dividing their attention between motor and cognitive tasks. Training studies have demonstrated that both cognitive and physical training regimens can improve motor and cognitive task performance. Few studies have examined the benefits of combined training (cognitive and physical) and whether or not this type of combined training would transfer to walking or balancing dual-tasks. This study examines the dual-task benefits of combined training in a sample of sedentary older adults. Seventy-two older adults (≥60 years) were randomly assigned to one of four training groups: Aerobic + Cognitive training (CT), Aerobic + Computer lessons (CL), Stretch + CT and Stretch + CL. It was expected that the Aerobic + CT group would demonstrate the largest benefits and that the active placebo control (Stretch + CL) would show the least benefits after training. Walking and standing balance were paired with an auditory n-back with two levels of difficulty (0- and 1-back). Dual-task walking and balance were assessed with: walk speed (m/s), cognitive accuracy (% correct) and several mediolateral sway measures for pre- to post-test improvements. All groups demonstrated improvements in walk speed from pre- ( = 1.33 m/s) to post-test ( = 1.42 m/s, < 0.001) and in accuracy from pre- ( = 97.57%) to post-test ( = 98.57%, = 0.005).They also increased their walk speed in the more difficult 1-back ( = 1.38 m/s) in comparison to the 0-back ( = 1.36 m/s, < 0.001) but reduced their accuracy in the 1-back ( = 96.39%) in comparison to the 0-back ( = 99.92%, < 0.001). Three out of the five mediolateral sway variables (Peak, SD, RMS) demonstrated significant reductions in sway from pre to post test ( < 0.05). With the exception of a group difference between Aerobic + CT and Stretch + CT in accuracy, there were no significant group differences after training. Results suggest that there can be dual-task benefits from training but that in this sedentary sample Aerobic + CT training was not more beneficial than other types of combined training.

When the performance of two tasks overlaps in time, performance impairments in one or both tasks are common. Various theoretical explanations for how component tasks are controlled in dual-task situations have been advanced. However, less attention has been paid to the issue of how two temporally overlapping tasks are appropriately coordinated in terms of their order. The current study focuses on two specific aspects of this task-order coordination: (1) the potential effects of practice on task-order coordination performance and (2) its relationships with cognitive meta-control mechanisms that adjust this coordination. These aspects were investigated in a visual-auditory dual-task combination with randomly changing task orders across trials after four sessions of dual-task practice ( N = 24) and single-task practice ( N = 24). The results demonstrated that task-order coordination improves during dual-task practice, and in contrast to the effects of single-task practice. Practice, on the other hand, did not show substantial evidence of an effect on the adjustment of task-order coordination. This practice-related dissociation is consistent with the assumption that (1) task-order coordination and (2) its sequential adjustment are separable sets of processes.

The speed with which information from vision is transformed into working memory (WM) representations that resist interference from ongoing perception and cognition is the subject of conflicting results. Using distinct paradigms, researchers have arrived at estimates of the consolidation time course ranging from 25 ms to 1 s – a range of more than an order of magnitude. However, comparisons of consolidation duration across very different estimation paradigms rely on the implicit assumption that WM consolidation speed is a stable, structural constraint of the WM system. The extremely large variation in WM consolidation speed estimates across measurement approaches motivated the current work’s goal of determining whether consolidation speed truly is a stable structural constraint of WM encoding, or instead might be under strategic control as suggested by some accounts. By manipulating the relative task priority of WM encoding and a subsequent sensorimotor decision in a dual-task paradigm, the current experiments demonstrate that the long duration of WM consolidation does not change as a result of task-specific strategies. These results allow comparison of WM consolidation across estimation approaches, are consistent with recent multi-phase WM consolidation models, and are consistent with consolidation duration being an inflexible structural limit.

Recently, some studies revealed that transcranial direct current stimulation (tDCS) reduces dual-task interference. Since there are countless combinations of dual-tasks, it remains unclear whether stable effects by tDCS can be observed on dual-task interference. An aim of the present study was to investigate whether the effects of tDCS on dual-task interference change depend on the dual-task content. We adopted two combinations of dual-tasks, i.e., a word task while performing a tandem task (word-tandem dual-task) and a classic Stroop task while performing a tandem task (Stroop-tandem dual-task). We expected that the Stroop task would recruit the dorsolateral prefrontal cortex (DLPFC) and require involvement of executive function to greater extent than the word task. Subsequently, we hypothesized that anodal tDCS over the DLPFC would improve executive function and result in more effective reduction of dual-task interference in the Stroop-tandem dual-task than in the word-tandem dual-task. Anodal or cathodal tDCS was applied over the DLPFC or the supplementary motor area using a constant current of 2.0 mA for 20 min. According to our results, dual-task interference and the task performances of each task under the single-task condition were not changed after applying any settings of tDCS. However, anodal tDCS over the left DLPFC significantly improved the word task performance immediately after tDCS under the dual-task condition. Our findings suggested that the effect of anodal tDCS over the left DLPFC varies on the task performance under the dual-task condition was changed depending on the dual-task content.

The objective of this exploratory randomized controlled trial (RCT) was to provide evidence for the feasibility and therapeutic value of a novel game-based dual-task balance exercise program in children with cerebral palsy (CP). Twenty children with CP were recruited and randomized into two groups: (a) the conventional balance training group (CG) and (b) the experimental group (XG), which received a game-based dual-task (DT) balance exercise program. Both groups received their respective therapy programs for 12 weeks at a frequency of three sessions per week. Semi-structured interviews with the parents and children and qualitative analysis were conducted to evaluate the children’s experiences with the game-based exercise program. The quantitative analysis included (a) the Pediatric Balance Scale (PBS), (b) Gross Motor Function Measure-88 (GMFM-88), and (c) computerized measures of standing balance performance during various dual-task conditions. Compliance was 100% for all 20 participants. Four themes captured the range of each participant’s experiences and opinions: (a) reasons for participation, (b) likes and dislikes with the technologies, (c) positive effects of the program, and (d) future expectations. Children in the XG demonstrated greater improvements in PBS, GMFM, and DT balance measures as compared to children in the CG. The findings demonstrate feasible trial procedures and acceptable DT-oriented training with a high compliance rate and positive outcomes. These findings support further research and development and progression to the next phase of a full-scale RCT to evaluate the clinical effectiveness of the game-based DT balance exercise program for children with CP.

When humans move both hands simultaneously, bimanual coupling or interference can occur. The circles‐lines paradigm is used to study the bimanual coupling and interference effects: Participants simultaneously draw either lines or circles with both hands (congruent), or draw lines with one hand and circles with the other hand (incongruent condition). Despite extensive behavioral research on bimanual coupling with this paradigm, our knowledge of the neural circuitry involved remains limited. Here, we capitalized on the advantages provided by functional near‐infrared spectroscopy to unveil the neural substrates of bimanual coupling within an ecologically valid experimental setting. Behavioral results confirmed previous literature, showing that the shapes become more oval due to the interference between the hands, causing the circle to resemble a line and vice versa. Additionally, performance in the congruent condition correlated with performance in the incongruent condition. From a neural perspective, we observed greater activity in sensorimotor areas and the right premotor area during the incongruent compared to the congruent condition. A novel temporal analysis of the time course of oxyhemoglobin signals revealed that the right hemisphere reached maximum amplitude before the left during the incongruent condition and revealed differences between conditions in parietal areas, showing that bimanual interference is associated not only with motor areas but also with associative areas. Finally, right inferior parietal lobe activity correlated with bimanual performance, suggesting a role for this area in bimanual tasks when the motor program of one hand is influenced by sensorimotor information from the contralateral hand. Our study demonstrates fNIRS effectiveness in investigating bimanual interference during the circles‐lines paradigm. fNIRS allows correct drawing positions, ensuring ecological validity. Performance in congruent tasks predicts incongruent performance. Time‐course analysis shows parietal differences, with the right hemisphere peaking earlier during the incongruent condition. Right inferior parietal lobe activity correlates with bimanual interference.