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The reliability of cognitive demand measures in controlled laboratory settings is well-documented; however, limited research has directly established their stability under real-life and high-stakes conditions, such as operating automated technology on actual highways. Partially automated vehicles have advanced to become an everyday mode of transportation, and research on driving these advanced vehicles requires reliable tools for evaluating the cognitive demand on motorists to sustain optimal engagement in the driving process. This study examined the reliability of five cognitive demand measures, while participants operated partially automated vehicles on real roads across four occasions. Seventy-one participants (aged 18-64 years) drove on actual highways while their heart rate, heart rate variability, electroencephalogram (EEG) alpha power, and behavioral performance on the Detection Response Task were measured simultaneously. Findings revealed that EEG alpha power had excellent test-retest reliability, heart rate and its variability were good, and Detection Response Task reaction time and hit-rate had moderate reliabilities. Thus, the current study addresses concerns regarding the reliability of these measures in assessing cognitive demand in real-world automation research, as acceptable test-retest reliabilities were found across all measures for drivers across occasions. Despite the high reliability of each measure, low intercorrelations among measures were observed, and internal consistency was better when cognitive demand was estimated as a multi-factorial construct. This suggests that they tap into different aspects of cognitive demand while operating automation in real life. The findings highlight that a combination of psychophysiological and behavioral methods can reliably capture multi-faceted cognitive demand in real-world automation research.

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When given a choice, people will avoid cognitively effortful courses of action because the experience of effort is evaluated as aversive and costly. At the same time, a body of work spanning psychology, economics, and neuroscience suggests that goods, actions, and experiences are often evaluated in the context in which they are encountered, rather in absolute terms. To probe the extent to which the evaluation of cognitive effort is also context-dependent, we had participants learn associations between unique stimuli and subjective demand levels across low-demand and high-demand contexts. We probed demand preferences and subjective evaluation using a forced-choice paradigm as well by examining effort ratings, taken both on-line (during learning) and off-line (after choice). When choosing between two stimuli objectively identical in terms of demand, participants showed a clear preference for the stimulus learned in the low- versus high-demand context and rated this stimulus as more subjectively effortful than the low-demand context in on-line but not off-line ratings, suggesting an assimilation effect. Finally, we observed that the extent to which individual participants who exhibited stronger assimilation effects in off-line demand ratings were more likely to manifest an assimilation effect in demand preferences. Broadly, our findings suggest that effort evaluations occur in a context-dependent manner and are specifically assimilated to the broader context in which they occur.

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This study aimed to evaluate the effect of age and intellectual disability (ID) on postural balance parameters, dual-task cost (DTC), and choice reaction time (CRT). Fifty-eight individuals with ID and 55 peers without ID performed a postural stance balance task under two conditions: a single task with eyes open and dual task involving an additional cognitive task (light sequence). Four postural balance parameters (total displacement, total sway area, mediolateral, and anteroposterior dispersion), cost of the dual task ([DTC%] = [(single-task performance - dual-task performance)/single-task performance] × 100), and CRT were recorded, calculated, and analyzed. All postural control parameters reflected poorerperformance during the dual-task condition, nevertheless, DTC was significantly higher only in individuals with ID and only for the total sway area, F(1, 111) = 5.039, p = .027, and mediolateral dispersion, F(1, 111) = 6.576, p = .012. CRT was longer in individuals with ID compared with the individuals without ID, F(1, 111) = 94.979, p ≤ .001, while age did not have a significant effect on the DTC nor on the CRT, F(1, 111) = 0.074, p = .786. In conclusion, an additional cognitive task during the postural balance task had a detrimental effect on various postural balance parameters, leading to increased DTC in terms of total sway area, mediolateral dispersion, and prolonged CRT in individuals with ID.

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Introduction: Extracts made from the leaves of the edible mango plant (Mangifera indica L., Anacardiaceae) have a long history of medicinal usage, most likely due to the presence of high levels of mangiferin, a polyphenol compound. Previous research has demonstrated that mango leaf extract (MLE) can beneficially modulate cognitive function in both animals and humans. This study aimed to assess the effects of an acute dose of 300 mg MLE (standardised to contain ≥60% mangiferin) on cognitive performance and mood in healthy adults. Methods: In this double-blind, placebo-controlled, crossover study, 114 healthy men and women (18-43 years) received either MLE or a matched placebo at each testing visit (separated by at least 7 days). Cognitive performance (including the cognitive demand battery) and mood were measured at 30, 180, and 300 min post-dose. Results: The results showed that, compared to placebo, the group taking MLE displayed a significant increase in serial 3 s and serial 7 s subtraction errors overall. There were no other significant effects on cognitive performance. Discussion: The results of the current study suggest that the consumption of 300 mg MLE in the absence of an observed multitasking psychological stressor does not improve cognitive performance or mood at up to 300 min post-dose. Due to the very limited nature of the effects and since they were observed among many analyses, these findings should be treated with caution.Clinical trial registration: http://ClinicalTrials.gov, identifier [NCT05182450].

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OBJECTIVES: Age-related changes in executive functions, especially inhibitory control, correlate to decreased balance control and increased fall risk. However, only a few studies focused on the performance of tasks integrating balance and inhibitory control. This study aims to determine the effects of cognitive inhibition preceding the initiation of voluntary steps in young and older adults. METHODS: Performance of 3 stepping tasks (a Simon, Flanker, and a combined Simon-Flanker task [SFT]) were analyzed in 23 young adults and 43 older adults. Each task included congruent and incongruent trials in different step directions. Analyses focused on temporal aspects of step responses as identified by changes in Center of Pressure (CoP) and foot position. A 3-way repeated-measures ANOVA was used to evaluate "inhibition," "age," and "task" effects. RESULTS: With large effect sizes, "inhibition" as well as "age" resulted in longer durations of an initial preparatory phase as well as the step response phase. The SFT showed the largest "task" effects. Duration of CoP movement had the largest impact on total step execution in older adults. A significant interaction effect of "age*inhibition" was found on the duration of CoP movement, but not on CoP onset. DISCUSSION: Overall, our results demonstrate that cognitive inhibition has more impact in older adults, the longer duration of CoP movements in older adults may reflect an ineffective step preparation. Our examination of the duration of subsequent phases which comprise perceptual processing and conflict resolution, response initiation, and step execution sheds light on how cognitive inhibition affects voluntary stepping behavior in young and older adults.

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Cranial electrotherapy stimulation (CES) delivers low-intensity electrical currents to the brain to treat anxiety, depression, and pain. Though CES is considered safe and cost-effective, little is known about side effects emerging across different contexts. Our objective was to investigate how varying physical and cognitive demands impact the frequency and intensity of CES vestibular sensations in a sample of healthy young adults. We used a 2 (stimulation: sham, active) × 2 (physical demand: static sway, dynamic sit-to-stand) × 2 (cognitive demand: single-task remain silent, dual-task count backward) repeated measures design. Vestibular sensations were measured with surveys and wearable sensors capturing balance changes. Active stimulation did not influence reported vestibular sensations. Instead, high physical demand predicted more sensation reports. High cognitive demand, but not active stimulation, predicted postural sway unsteadiness. Significant effects of active stimulation on balance were observed only during the dynamic sit-to-stand transitions. In summary, CES induces vestibular sensations only for a specific outcome under certain circumstances. Our findings imply that consumers can safely maximize the benefits of CES while ensuring they are taking steps to minimize any potential side effects by considering their context and circumstances.

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Eccentric, compared to concentric exercise, is proposed to involve different neuro-motor processing strategies and a higher level of mental demand. This study compared eccentric and concentric cycling at matched perceived effort and torque for the mental demand and related-cortical activation patterns. Nineteen men (30 ± 6 years) performed four different 5-min cycling conditions at 30 RPM on a semi-recumbent isokinetic cycle ergometer: (1) concentric at a moderate perceived effort (23 on the CR100® scale) without torque feedback; (2) concentric and (3) eccentric at the same average torque produced in the first condition; and (4) eccentric at the same moderate perceived effort than the first concentric condition. The conditions two to four were randomized. After each condition, mental demand was monitored using the NASA Task Load Index scale. Changes in oxy-(O2 Hb) and deoxy-(HHb) hemoglobin during exercise were measured over both prefrontal cortices and the right parietal lobe from a 15-probe layout using a continuous-wave NIRS system. Mental demand was significantly higher during eccentric compared to concentric cycling (+52%, p = 0.012) and when the exercise intensity was fixed by the torque rather than the perceived effort (+70%, p < 0.001). For both torque- or perceived effort-matched exercises, O2 Hb increased significantly (p < 0.001) in the left and right prefrontal cortices, and right parietal lobe, and HHb decreased in the left, and right, prefrontal cortices during eccentric compared to concentric cycling. This study supports that acute eccentric cycling, compared to concentric cycling, involves a higher mental demand, and frontoparietal network activation.

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Motivation plays a role when a listener needs to understand speech under acoustically demanding conditions. Previous work has demonstrated pupil-linked arousal being sensitive to both listening demands and motivational state during listening. It is less clear how motivational state affects the temporal evolution of the pupil size and its relation to subsequent behavior. We used an auditory gap detection task (N = 33) to study the joint impact of listening demand and motivational state on the pupil size response and examine its temporal evolution. Task difficulty and a listener's motivational state were orthogonally manipulated through changes in gap duration and monetary reward prospect. We show that participants' performance decreased with task difficulty, but that reward prospect enhanced performance under hard listening conditions. Pupil size increased with both increased task difficulty and higher reward prospect, and this reward prospect effect was largest under difficult listening conditions. Moreover, pupil size time courses differed between detected and missed gaps, suggesting that the pupil response indicates upcoming behavior. Larger pre-gap pupil size was further associated with faster response times on a trial-by-trial within-participant level. Our results reiterate the utility of pupil size as an objective and temporally sensitive measure in audiology. However, such assessments of cognitive resource recruitment need to consider the individual's motivational state.

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CLINICAL RELEVANCE: Research on infantile nystagmus syndrome (INS) and visual search is limited. Conducting this research could assist practitioners in understanding how INS affects the real-life visual activities of patients and aid in developing new clinical visual function assessments for INS. BACKGROUND: The aim of this work is to investigate how subjects with INS perform visual search tasks, and, particularly, to assess how INS subjects perform when targets are located at their null position or away from it, and when under additional cognitive demands. METHODS: INS subjects (N = 15) and controls (N = 20) performed conjunction and feature search tasks, both with and without mental arithmetic. Search performance was assessed using log-transformed total search time, gaze-dependent search time, and accuracy. Cognitive demand was quantified by pupil size and the NASA task-load index score. RESULTS: INS subjects showed longer search times compared to controls in conjunction search (P < 0.01), but not in feature search. Within INS and control subjects, the total search times were significantly increased by the addition of mental arithmetic (P < 0.0001). There was no difference in gaze-dependent search times between null target position and 15° away from null target position of subjects in conjunction search (P > 0.05). Accuracies were 100% for both control and INS subjects in both conjunction and feature search. CONCLUSION: Conjunction visual search was impaired in adult INS subjects, and further worsened under increased cognitive demand. The null position did not affect the visual search performance in INS.

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Previous studies reported that the inferior parietal lobule (IPL) had lower activation during visuospatial attention in children with attention-deficit/hyperactivity disorder (ADHD), while the functional connectivity (FC) between the IPL and other brain regions and how cognitive demand might modulate IPL's FC remain unclear. We performed a functional magnetic resonance imaging experiment recruiting two task conditions with relatively low and high cognitive demand of visuospatial attention. Forty-four children with ADHD and 36 age- and sex-matched healthy controls were included. IPL's regional activation and FC intensities were compared between groups and correlated with clinical measurements. We found that the IPL had significantly reduced activation in children with ADHD compared to healthy controls and this abnormal activation was not modulated by the cognitive demand of visuospatial attention. Importantly, further analysis revealed that the functional connectivity between IPL and inferior frontal gyrus was modulated by the cognitive demand of visuospatial attention in children with ADHD. These results revealed a modulatory effect of cognitive demand of visuospatial attention on IPL's functional connectivity but not IPL's activation in children with ADHD. More generally, these results highlight the functional reorganization of the brain activity as a possible compensatory strategy in response to the symptoms of ADHD.

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Cognitive demand is thought to modulate two often used, but rarely combined, measures: pupil size and neural α (8-12 Hz) oscillatory power. However, it is unclear whether these two measures capture cognitive demand in a similar way under complex audiovisual-task conditions. Here we recorded pupil size and neural α power (using electroencephalography), while human participants of both sexes concurrently performed a visual multiple object-tracking task and an auditory gap detection task. Difficulties of the two tasks were manipulated independent of each other. Participants' performance decreased in accuracy and speed with increasing cognitive demand. Pupil size increased with increasing difficulty for both the auditory and the visual task. In contrast, α power showed diverging neural dynamics: parietal α power decreased with increasing difficulty in the visual task, but not with increasing difficulty in the auditory task. Furthermore, independent of task difficulty, within-participant trial-by-trial fluctuations in pupil size were negatively correlated with α power. Difficulty-induced changes in pupil size and α power, however, did not correlate, which is consistent with their different cognitive-demand sensitivities. Overall, the current study demonstrates that the dynamics of the neurophysiological indices of cognitive demand and associated effort are multifaceted and potentially modality-dependent under complex audiovisual-task conditions.SIGNIFICANCE STATEMENT Pupil size and oscillatory α power are associated with cognitive demand and effort, but their relative sensitivity under complex audiovisual-task conditions is unclear, as is the extent to which they share underlying mechanisms. Using an audiovisual dual-task paradigm, we show that pupil size increases with increasing cognitive demands for both audition and vision. In contrast, changes in oscillatory α power depend on the respective task demands: parietal α power decreases with visual demand but not with auditory task demand. Hence, pupil size and α power show different sensitivity to cognitive demands, perhaps suggesting partly different underlying neural mechanisms.

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The multiple-demand (MD) network is sensitive to many aspects of cognitive demand, showing increased activation with more difficult tasks. However, it is currently unknown whether the MD network is modulated by the context in which task difficulty is experienced. Using functional magnetic resonance imaging, we examined MD network responses to low, medium, and high difficulty arithmetic problems within 2 cued contexts, an easy versus a hard set. The results showed that MD activity varied reliably with the absolute difficulty of a problem, independent of the context in which the problem was presented. Similarly, MD activity during task execution was independent of the difficulty of the previous trial. Representational similarity analysis further supported that representational distances in the MD network were consistent with a context-independent code. Finally, we identified several regions outside the MD network that showed context-dependent coding, including the inferior parietal lobule, paracentral lobule, posterior insula, and large areas of the visual cortex. In sum, a cognitive effort is processed by the MD network in a context-independent manner. We suggest that this absolute coding of cognitive demand in the MD network reflects the limited range of task difficulty that can be supported by the cognitive apparatus.

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While classical studies have highlighted the many potential benefits of using original historical sources in the classroom, few studies have documented actual classroom practices outside of research contexts. In this case study, I aim to describe and explain how five French high school teachers autonomously designed and implemented classroom sessions starting from the same document, namely an excerpt from Euler's Elements of Algebra presenting an algorithm for square root approximation. From a methodological viewpoint, it enables me show how two general frameworks for the study of teachers' professional practices-the Documentational Approach to Didactics and the Didactic and Ergonomic Double Approach-can be tailored to fit the specific challenges of using historical sources. The empirical results provide fresh insights into the conditions for a mathematically rich use of historical sources in the classroom, and on the connections between this use and the integration of a historical perspective in the teaching of mathematics.

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The societal burden of Alzheimer's Disease (AD) and other major forms of dementia continues to grow, and multiple pharmacological agents directed towards modifying the pathological "hallmarks" of AD have yielded disappointing results. Though efforts continue towards broadening and deepening our knowledge and understanding of the mechanistic and neuropathological underpinnings of AD, our previous failures motivate a re-examination of how we conceptualize AD pathology and progression. In addition to not yielding effective treatments, the phenotypically heterogeneous biological processes that have been the primary area of focus to date have not been adequately shown to be necessary or sufficient to explain the risk and progression of AD. On the other hand, a growing body of evidence indicates that lifestyle and environment represent the ultimate level of causation for AD and age-related cognitive decline. Specifically, the decline in cognitive demands over the lifespan plays a central role in driving the structural and functional deteriorations of the brain. In the absence of adequate cognitive stimulus, physiological demand-function coupling leads to downregulation of growth, repair, and homeostatic processes, resulting in deteriorating brain tissue health, function, and capacity. In this setting, the heterogeneity of associated neuropathological tissue hallmarks then occurs as a consequence of an individual's genetic and environmental background and are best considered downstream markers of the disease process rather than specific targets for direct intervention. In this manuscript we outline the evidence for a demand-driven model of age-related cognitive decline and dementia and why it mandates a holistic approach to dementia treatment and prevention that incorporates the primary upstream role of cognitive demand.

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Aim: Participation in classroom physical activity breaks may improve children's cognition, but few studies have involved adolescents. The primary aim of this study was to examine the effects of classroom-based resistance training with and without cognitive training on adolescents' cognitive function. Methods: Participants were 97 secondary school students (45.4% females, mean age 15.78 ± 0.44). Four-year 10 classes from one school were included in this four-arm cluster randomized controlled trial. Classes were randomly assigned to the following groups: sedentary control with no cognitive training, sedentary with cognitive training, resistance training without cognitive training, and resistance training with cognitive training. Sessions varied in levels of both cognitive demand and resistance training (i.e., high vs. low) and were administered three times per week for 4 weeks (12 sessions). Inhibition, cognitive flexibility, episodic memory, on-task behavior, and muscular fitness were assessed at baseline and post-test. Linear mixed models were used to examine changes within and between groups. Results: In comparison with the control group, episodic memory improved significantly in the resistance training without cognitive training group (-9.87 units, 95% CI: -17.71 to -2.03, p = 0.014, d = 0.72). There were no group-by-time effects for inhibition or cognitive flexibility. Classroom activity breaks both with and without cognitive demand improved participants' on-task behavior in comparison with the control and sedentary group. The resistance training programs did not lead to improvements in muscular fitness. Conclusion: Participation in body weight resistance training without cognitive training led to selective improvements in episodic memory. No training effects were found for inhibition or cognitive flexibility. A longer study period may be necessary to induce improvements in muscular fitness and associated changes in inhibition and cognitive flexibility. Clinical Trial Registration: https://www.anzctr.org.au/ACTRN12621001341819.aspx, Australian New Zealand Clinical Trials Registry-ACTRN12621001341819.

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Introduction: Dual-task studies have demonstrated that walking is attention-demanding for younger adults. However, numerous studies have attributed this to task type rather than the amount of required to accomplish the task. This study examined four tasks: two discrete (i.e., short intervals of attention) and two continuous (i.e., sustained attention) to determine whether greater attentional demands result in greater dual-task costs due to an overloaded processing capacity. Methods: Nineteen young adults (21.5 ± 3.6 years, 13 females) completed simple reaction time (SRT) and go/no-go (GNG) discrete cognitive tasks and n-back (NBK) and double number sequence (DNS) continuous cognitive tasks with or without self-paced walking. Prefrontal cerebral hemodynamics were measured using functional near-infrared spectroscopy (fNIRS) and performance was measured using response time, accuracy, and gait speed. Results: Repeated measures ANOVAs revealed decreased accuracy with increasing cognitive demands (p = 0.001) and increased dual-task accuracy costs (p < 0.001). Response times were faster during the single compared to dual-tasks during the SRT (p = 0.005) and NBK (p = 0.004). DNS gait speed was also slower in the dual compared to single task (p < 0.001). Neural findings revealed marginally significant interactions between dual-task walking and walking alone in the DNS (p = 0.06) and dual -task walking compared to the NBK cognitive task alone (p = 0.05). Conclusion: Neural findings suggest a trend towards increased PFC activation during continuous tasks. Cognitive and motor measures revealed worse performance during the discrete compared to continuous tasks. Future studies should consider examining different attentional demands of motor tasks.

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This preliminary study assessed the effects of noise and stimulus presentation order on recall of spoken words and recorded pupil sizes while normal-hearing listeners were trying to encode a series of words for a subsequent recall task. In three listening conditions (stationary noise in Experiment 1; quiet versus four-talker babble in Experiment 2), participants were assigned to remember as many words as possible to recall them in any order after each list of seven sentences. In the two noise conditions, lists of sentences fixed at 65 dB SPL were presented at an easily audible level via a loudspeaker. Reading span (RS) scores were used as a grouping variable, based on a median split. The primacy effect was present apart from the noise interference, and the high-RS group significantly outperformed the low-RS group at free recall measured in the quiet and four-talker babble noise conditions. RS scores were positively correlated with free-recall scores. In both quiet and four-talker babble noise conditions, sentence baselines after correction to the initial stimulus baseline increased significantly with increasing memory load. Larger sentence baselines but smaller peak pupil dilations seemed to be associated with noise interruption. The analysis method of pupil dilation used in this study is likely to provide a more thorough understanding of how listeners respond to a later recall task in comparison with previously used methods. Further studies are needed to confirm the applicability of our method in people with impaired hearing using multiple repetitions to estimate the allocation of relevant cognitive resources.

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Neuroimaging studies for human participants have shown that the activity in the multiple-demand (MD) network is associated with various kinds of cognitive demand. However, surprisingly, it remains unclear how this MD network is related to a core component of cognition, the process of searching for a target among distractors. This was because previous neuroimaging studies of visual search were confounded by task difficulty or time on task. To circumvent these limitations, we examined human brain activity while participants perform two different visual search tasks. The performance of a task was limited by increased attentional demand, while the other task was primarily limited by poor quality of input data or neural noise. Throughout the MD network, increased activity and strengthened functional connectivity among the MD regions were observed under the search task recruiting capacity-limited attentional resources. The present findings provide unequivocal evidence that the MD network mediates visual search, as well as other capacity-limited cognitive processes.

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PURPOSE: To determine the effect of cognitive-motor dual-task load on temporal structure irregularity (complexity) of motor output and task performance of submaximal isometric contractions. METHODS: Twelve young, sedentary subjects performed handgrip isometric contractions until failure at 50% of maximal voluntary contraction under mathematical self-regulated dual-task (own pace; SDT), regulated dual-task (imposed pace; RDT), and control. Force signal complexity was calculated by sample entropy at the initial, middle, and final thirds. Task performance was assessed by muscle fatigue (time to failure and rate of median frequency of the radial flexor of the carpus), force and math task error, and self-perceived difficulty. RESULTS: Only RDT decreased complexity with respect to control (17.4% ± 12.6%, p = 0.005), all conditions decreased complexity by the final third (Control: 52.8% ± 18.7%, p < 0.001; SDT: 41.1% ± 32.1%, p = 0.003; RDT: 19.1% ± 21.9%, p = 0.035). Conditions did not affect time to failure, and only RDT decreased the rate of median frequency (0.1%/s ± 0.1%/s, p = 0.020). Inferior force error rate was increased by conditions (SDT: 1.5% ± 0.8%, p < 0.001; RDT: 2% ± 1.5%, p = 0.002). Math error was only augmented by RDT (from 9.9 ± 6.7 to 51.7 ± 18.8, p < 0.001), categorized as "very hard" in 85.7% of participants (p = 0.015). CONCLUSION: Only the RDT condition reduced complexity and neuromuscular fatigue while increasing force error rate of the handgrip's motor output, without affecting time to failure. A highly demanding dual-task may become a strategy to modify the organization of the hand force motor output, which may contribute to its motor adaptations.

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This study was designed to investigate the neural mechanism of cognitive modulation of pain via a reappraisal strategy with high temporal resolution. The EEG signal was recorded from 29 participants who were instructed to down-regulate, up-regulate, or maintain their pain experience. The L2 minimum norm source reconstruction method was used to localize areas in which a significant effect of the instruction was present. Down-regulating pain by reappraisal exerted a robust effect on pain processing from as early as ~100 ms that diminished the activity of limbic brain regions: the anterior cingulate cortex, right orbitofrontal cortex, left anterior temporal region, and left insula. However, compared with the no-regulation condition, the neural activity was similarly attenuated in the up- and down-regulation conditions. We suggest that this effect could be ascribed to the cognitive load that was associated with the execution of a cognitively demanding reappraisal task that could have produced a general attenuation of pain-related areas regardless of the aim of the reappraisal task (i.e., up- or down-regulation attempts). These findings indicate that reappraisal effects reflect the joint influence of both reappraisal-specific (cognitive change) and unspecific (cognitive demand) factors, thus pointing to the importance of cautiously selected control conditions that allow the modulating impact of both processes to be distinguished.

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