Repeat Trials Research Articles

Hypervigilance strikes a balance between external and internal attention: behavioral and modeling evidence from the switching attention task.

Hypervigilance involves increased attentional scanning of the environment to facilitate the detection of possible threats. Accordingly, this state is mostly bound to external attention and as a corollary, it might be detrimental to internal attention and further affect attentional balance defined as the ability to switch dynamically between these two domains. In the current study, we aimed to address this question and induced hypervigilance in 49 healthy participants through the presentation of a task-unrelated aversive sound while they performed the switching attention task (SAT), which was previously devised to study attentional balance. The skin conductance response results, as well as subjective sound ratings, confirmed that the hypervigilance manipulation was successful. At the behavioral level, hypervigilance led to a more symmetrical balance between internal and external attention compared to the control and neutral conditions, where it was asymmetrical, replicating previous studies. Moreover, using a drift diffusion model, we found that hypervigilance reduced the drift rate for internal repetition trials, suggesting that hypervigilance possibly caused an impaired shielding of internal attention.

Statistical variation of the burning rate and extinction characteristics of engineered timber products

Understanding the burning rate (mass loss rate, MLR) of timber products is essential in characterizing the ignition characteristics, fire size, and extinction phenomena experienced by timber. Key parameters for timber, such as self-extinction criteria, are presented throughout literature. These parameters are often determined using bench-scale experiments in relatively low trial quantities (e.g., n = 3). This study investigates the influence of trial quantity on the observed statistical variation in key burning rate metrics for timber products (e.g., peak MLR, MLR at extinction). Experiments were performed using a conical heater to conduct 100 repeat trials at incident heat fluxes of 20 kW/m2, 40 kW/m2, and 50 kW/m2 on 12.7 mm (0.5 in.) thick ACX cross laminated plywood samples. Significant variability was observed in trials conducted at 40 kW/m2 due to bimodal behavior where 39% of samples experienced self-extinction and the remaining 61% of samples sustained combustion until burnout (i.e., complete pyrolysis of the material). The MLR at extinction for the trials at 40 kW/m2 displayed nearly double the magnitude compared to trials conducted at 20 kW/m2 due to the breakdown of the semi-infinite solid condition. The results from this work illustrate the significance of large trial quantities when investigating complex phenomena.

Cerebral Vasomotor Reactivity to Carbon Dioxide Using the Rebreathe Technique: Assessment of Within-day and Between-day Repeatability.

The cerebral vasodilator response to increased arterial carbon dioxide (CO2) concentration, termed cerebral vasomotor reactivity (CVMR), is used to assess cerebral vascular function. We sought to assess the within-day and between-day repeatability of CVMR to rebreathing-induced hypercapnia. Twelve healthy adults performed a within-day short interval protocol (17±2 minutes between trials), ten performed a within-day long interval protocol (145±16 minutes between trials), and seventeen performed a between-day protocol (5±2 days between visits). Repeatability of the slope of the percent change in middle cerebral artery mean blood velocity (%MCAvmean) and cerebral vascular conductance index (%CVCi), to the change in partial pressure of end-tidal CO2 (PETCO2) between the two trials/days was assessed. Within-day short interval %MCAvmean slope demonstrated fair to excellent repeatability (intraclass correlation, ICC=0.92 [95% confidence interval 0.72-0.98]; p<0.001) while %CVCi slope showed more variability (ICC=0.84 [0.47-0.95]; p=0.002]). Within-day long interval, %MCAvmean (ICC=0.95 [0.80-0.99]) and %CVCi (ICC=0.94 [0.71-0.99]) slopes showed good to excellent and fair to excellent repeatability respectively (p<0.001 for both). For between-day trials, better repeatability was observed for %CVCi (ICC=0.85 [0.57-0.95]; p<0.001) compared to %MCAvmean (ICC=0.76 [0.33-0.91]; p=0.004) slope. These findings indicate repeatable within- and between-day CVMR responses to rebreathe induced hypercapnia. However, a longer interval may be better for within-day repeat trials, particularly for CVCi measures.

Distraction by unexpected sounds: comparing response repetition and response switching.

Numerous studies using oddball tasks have shown that unexpected sounds presented in a predictable or repeated sequence (deviant vs. standard sounds) capture attention and negatively impact ongoing behavioral performance. Here, we examine an aspect of this effect that has gone relatively unnoticed: the impact of deviant sounds is stronger for response repetitions than for response switches. Our approach was two-fold. First, we carried out a simulation to estimate the likelihood that stimuli sequences used in past work may not have used balanced proportions of response repetition and switch trials. More specifically, we sought to determine whether the larger distraction effect for response repetitions may have reflected a rarer, and thereby more surprising, occurrence of such trials. To do so, we simulated 10,000 stimuli sets for a 2-AFC task with a proportion of deviant trial of 0.1 or 0.16. Second, we carried out a 2-AFC oddball task in which participants judged the duration of a tone (short vs. long). We carefully controlled the sequence of stimuli to ensure to balance the proportions of response repetitions and response switches across the standard and deviant conditions. The results of the stimuli simulation showed that, contrary to our concerns, response switches were more likely than response repetitions when left uncontrolled for. This suggests that the larger distraction found for response repetition in past work may in fact have been underestimated. In the tone duration judgment task, the results showed a large impact of the response type on distraction as measured by response times: Deviants sounds significantly delayed response repetitions but notably accelerated switches. These findings suggest that deviant sound hinder response repetition and encourage or bias the cognitive system towards a change of responses. We discuss these findings in relation to the adaptive nature of the involuntary detection of unexpected stimuli and in relation to the notion of partial repetition costs. We argue that results are in line with the binding account as well as with the signaling theory.

Age-related Electrophysical Correlates of Cross-modal Attention Switching.

The human experience demands seamless attentional switches between sensory modalities. Aging raises questions about how declines in auditory and visual processing affect cross-modal attention switching. This study used a cued cross-modal attention-switching paradigm where visual and auditory stimuli were simultaneously presented on either spatially congruent or incongruent sides. A modality cue indicated the target modality, requiring a spatially left versus right key-press response. EEG recordings were collected during task performance. We investigated whether the mixing costs (decreased performance for repetition trials in a mixed task compared with a single task) and switch costs (decreased performance for a switch of target modality compared with a repetition) in cross-modal attention-switching paradigms would exhibit similarities in terms of behavioral performance and the ERP components to those observed in the traditional unimodal attention-switching paradigms. Specifically, we focused on the ERP components: cue-locked P3 (mixing/switch-related increased positivity), target-locked P3 (mixing/switch-related decreased positivity), and target-locked lateralized readiness potential (mixing/switch-related longer latency). In addition, we assessed how aging impacts cross-modal attention-switching performance. Results revealed that older adults exhibited more pronounced mixing and switch costs than younger adults, especially when visual and auditory stimuli were presented on incongruent sides. ERP findings showed increased cue-locked P3 amplitude, prolonged cue-locked P3 latency, decreased target-locked P3 amplitude, prolonged target-locked P3 latency in association with switch costs, and prolonged onset latency of the target-locked lateralized readiness potential in association with the mixing costs. Age-related effects were significant only for cue-locked P3 amplitude, cue-locked P3 latency (switch-related), and target-locked P3 latency (switch-related). These findings suggest that the larger mixing costs and switch costs in older adults were because of the inefficient use of modality cues to update a representation of the relevant task sets and required more processing time for evaluating and categorizing the target.

Feasibility of Using Standardized Outcome Measures in the Remote Assessment of Patients with Chronic Stroke: A Case Series

Introduction: With the increase of telerehabilitation utilization worldwide after the COVID-19 pandemic, a review of the current literature shows a concurrent increase in telerehabilitation studies focusing on interventions and delivery models. There is a gap in research on valid and reliable tests and measures that can be used in the physical therapy examination of people with stroke via telerehabilitation. Current reports on psychometric properties of most standardized outcome measures are only applicable in an in-person setting and may not be directly applicable in a remote setting where various challenges contribute to the reliability of results. This report describes the feasibility of administering selected standardized outcome measures in the remote assessment of three patients with chronic stroke with different contexts. Methods: Three patients with chronic stroke underwent physical therapy examination and intervention sessions via telerehabilitation with varying contexts. Results: Various factors affected the results of the assessment including patient and caregiver’s (if present) ability to follow instructions, availability of material and spatial resources, and stability of internet connection. Strategies to improve reliability of assessment results can also be employed such as performing repeat trials, reviewing recordings for accuracy and confirmation, using highly visible markers, and confirming measurement accuracy on video. Discussion: Physical therapy outcome measures that can feasibly be administered remotely are the Timed Up and Go Test, the 10-Meter Walk Test, the 6-Minute Walk Test, the 5-Times Sit to Stand Test, and the Stroke Impact Scale. The Mini Balance Evaluation Systems Test could not be administered remotely as close to standard protocol as possible due to the difficulty of administering the reactive postural component with patient anxiety and safety considerations and materials required.

Target switch costs in visual search arise during the preparatory activation of target templates.

Prior research on task switching has shown that the reconfiguration of stimulus-response mappings across trials is associated with behavioral switch costs. Here, we investigated the effects of switching representations of target-defining features in visual search (attentional templates). Participants searched for one of two color-defined target objects that changed predictably every two trials (Experiment 1) or every four trials (Experiment 2). Substantial costs were observed for search performance on target switch relative to target repeat trials. Preparatory target template activation processes were tracked by measuring N2pc components (indicative of attentional capture) to a rapid series of task-irrelevant color singleton probes that appeared during the interval between search displays, and either matched the currently relevant or the other target color. N2pcs to relevant target color probes emerged from 800 ms before search display onset on target repetition trials, reflecting the activation of a corresponding color template. Crucially, probe N2pcs only emerged immediately before target onset on target switch trials, indicating that preparatory template activation was strongly delayed. In contrast, irrelevant color singleton probes did not trigger N2pcs on either repeat or switch trials, suggesting the absence of any target template inertia across trials. These results show that switching the identity of search targets delays preparatory target template activation and impairs subsequent attentional guidance processes. They suggest that performance costs on switch versus repeat trials are associated with differences in the time course of task preparation.

Domain-general cognitive control processes in bilingual switching: Evidence from midfrontal theta oscillations.

Language control in bilingual speakers is thought to be implicated in effectively switching between languages, inhibiting the non-intended language, and continuously monitoring what to say and what has been said. It has been a matter of controversy concerning whether language control operates in a comparable manner to cognitive control processes in non-linguistic domains (domain-general) or if it is exclusive to language processing (domain-specific). As midfrontal theta oscillations have been considered as an index of cognitive control, examining whether a midfrontal theta effect is evident in tasks requiring bilingual control could bring new insights to the ongoing debate. To this end, we reanalysed the EEG data from two previous bilingual production studies where Dutch-English bilinguals named pictures based on colour cues. Specifically, we focused on three fundamental control processes in bilingual production: switching between languages, inhibition of the nontarget language, and monitoring of speech errors. Theta power increase was observed in switch trials compared to repeat trials, with a midfrontal scalp distribution. However, no theta power difference was observed in switch trials following a shorter sequence of same-language trials compared to a longer sequence, suggesting a missing modulation of inhibitory control. Similarly, increased midfrontal theta power was observed when participants failed to switch to the intended language compared to correct responses. Altogether, these findings tentatively support the involvement of domain-general cognitive control mechanisms in bilingual switching.

The association between insomnia symptoms and cognitive flexibility among undergraduates: An event-related potential study

ObjectiveTo explore the association between insomnia symptoms and cognitive flexibility among undergraduates, along with its potential neural mechanisms. MethodA total of 102 participants were divided into insomnia (n = 55) and control (n = 47) groups based on sleep status. Cognitive flexibility was assessed using the Cognitive Flexibility Inventory (CFI) and the Number-Letter Task (N-L task). EEG data were recorded during the N-L task. ResultsThe insomnia group exhibited lower CFI scores and higher switch costs in reaction time and accuracy compared to the control group. ERP analysis showed differences in P2, N2, and P3 component amplitudes between the two groups, with reduced N2 amplitude in the insomnia group under repeat trials. Time-frequency analysis revealed larger theta band event related synchronization in the frontal region and smaller theta band ERS in the parietal region under switch trials in the control group; the alpha band event-related desynchronization in the parietal region under repeat trials was significantly smaller in the control group compared to switch trials. ConclusionCompared to undergraduates with normal sleep, those with insomnia symptoms exhibited reduced cognitive flexibility, which may be associated with some alterations in brain electrophysiological activities.

Enhancing Clinical Diagnosis With Convolutional Neural Networks: Developing High-Accuracy Deep Learning Models for Differentiating Thoracic Pathologies.

Background The use of computational technology in medicine has allowed for an increase in the accuracy of clinical diagnosis, reducing errors through additional layers of oversight. Artificial intelligence technologies present the potential to further augment and expedite the accuracy, quality, and efficiency at which diagnosis can be made when used as an adjunctive tool. Such techniques, if found to be accurate and reliable in their diagnostic acuity, can be implemented to foster better clinical decision-making, improving patient quality of care while reducing healthcare costs. Methodology This study implemented convolution neural networks to develop a deep learning model capable of differentiating normal chest X-rays from those indicating pneumonia, tuberculosis, cardiomegaly, and COVID-19. There were 3,063 normal chest X-rays, 3,098 pneumonia chest X-rays, 2,920 COVID-19 chest X-rays, 2,214 chest X-rays, and 554 tuberculosis chest X-rays from Kaggle that were used for training and validation.The model was trained to recognize patterns within the chest X-rays to efficiently recognize these diseases within patients to be treated on time. Results The results indicated a success rate of 98.34% incorrect detections, exemplifying a high degree of accuracy. There are limitations to this study. Training models require hundreds to thousands of samples, and due to potential variability in image scanning equipment and techniques from which the images are sourced, the model could have learned to interpret external noise and unintended details which can adversely impact accuracy. Conclusions Further studies that implement more universal database-sourced images with similar image scanning techniques, assess diverse but related medical conditions, and the utilization of repeat trials can help assess the reliability of the model.These results highlight the potential of machine learning algorithms for disease detection with chest X-rays.

The precision of signals encoding active self-movement.

Everyday actions like moving the head, walking around, and grasping objects are typically self-controlled. This presents a problem when studying the signals encoding such actions because active self-movement is difficult to control experimentally. Available techniques demand repeatable trials, but each action is unique, making it difficult to measure fundamental properties like psychophysical thresholds. We present a novel paradigm that recovers both precision and bias of self-movement signals with minimal constraint on the participant. The paradigm relies on linking image motion to previous self-movement, and two experimental phases to extract the signal encoding the latter. The paradigm takes care of a hidden source of external noise not previously accounted for in techniques that link display motion to self-movement in real time (e.g., virtual reality). We use head rotations as an example of self-movement, and show that the precision of the signals encoding head movement depends on whether they are being used to judge visual motion or auditory motion. We find that perceived motion is slowed during head movement in both cases. The "nonimage" signals encoding active head rotation (motor commands, proprioception, and vestibular cues) are therefore biased toward lower speeds and/or displacements. In a second experiment, we trained participants to rotate their heads at different rates and found that the imprecision of the head rotation signal rises proportionally with head speed (Weber's law). We discuss the findings in terms of the different motion cues used by vision and hearing, and the implications they have for Bayesian models of motion perception.NEW & NOTEWORTHY We present a psychophysical technique for measuring the precision of signals encoding active self-movements. Using head movements, we show that 1) precision is greater when active head rotation is performed using visual comparison stimuli versus auditory; 2) precision decreases with head speed (Weber's law); 3) perceived speed is lower during head rotation. The findings may reflect the steps needed to convert different cues into common units, and challenge standard Bayesian models of motion perception.

Trial of labour following two previous caesarean sections – A UK cohort study

ObjectivesTo assess the (i) predictors of and associated rates of success and; (ii) maternal and perinatal outcomes of women undergoing trial of labour after two previous caesarean sections (TOLA2C). Study designThis retrospective cohort study collected data from two regional obstetric centres with 12,000 deliveries per annum collectively. The population included singleton pregnancies undergoing (i) TOLA2C, (ii) elective repeat caesarean section following two caesarean sections (ERCS) and (iii) trial of labour after one caesarean section (TOLA1C). Data was collected electronically from 2013 to 2021. Statistical analysis included Fisher exact and Kruskal-Wallis test to compare unpaired samples alongside univariate and multivariable logistic regression. The primary outcome measure was maternal and perinatal outcome. ResultsThe three groups included; n = 146 TOLA2C, n = 206 ERCS and n = 99 TOLA1C. TOLA2C had a success rate of 65 % compared to 74 % for TOLA1C (p = 0.16). The optimal predictor of successful TOLA2C was previous successful TOLA1C OR 8.65 (95 % CI 2.75–38.41). TOLA2C was associated with greater risk of endometritis and/or sepsis postnatally compared to the other two groups [10.3 % (n = 15) versus 0.5 % (n = 1) and 3 % (n = 3) for ERCS and TOLA1C respectively p < 0.01]. It was also associated with longer maternal hospital stay [2.4 days (+/-1.8) versus 1.8 (+/-0.8) and 1.8 (+/-1.7) p < 0.01], a greater proportion of neonates with Apgar scores less than 7 (p=<0.01) and higher rates of neonatal unit admission [14 % (n = 20) versus 5 % (n = 11) versus 4 % (n = 4) (p=<0.01)]. ConclusionWomen considering trial of labour following two caesarean sections should be counselled regarding the potential increased risk of endometritis, sepsis and adverse neonatal outcome.

Low-rank human-like agents are trusted more and blamed less in human-autonomy teaming.

If humans are to team with artificial teammates, factors that influence trust and shared accountability must be considered when designing agents. This study investigates the influence of anthropomorphism, rank, decision cost, and task difficulty on trust in human-autonomous teams (HAT) and how blame is apportioned if shared tasks fail. Participants (N = 31) completed repeated trials with an artificial teammate using a low-fidelity variation of an air-traffic control game. We manipulated anthropomorphism (human-like or machine-like), military rank of artificial teammates using three-star (superiors), two-star (peers), or one-star (subordinate) agents, the perceived payload of vehicles with people or supplies onboard, and task difficulty with easy or hard missions using a within-subject design. A behavioural measure of trust was inferred when participants accepted agent recommendations, and a measure of no trust when recommendations were rejected or ignored. We analysed the data for trust using binomial logistic regression. After each trial, blame was apportioned using a 2-item scale and analysed using a one-way repeated measures ANOVA. A post-experiment questionnaire obtained participants' power distance orientation using a seven-item scale. Possible power-related effects on trust and blame apportioning are discussed. Our findings suggest that artificial agents with higher levels of anthropomorphism and lower levels of rank increased trust and shared accountability, with human team members accepting more blame for team failures.

Relationship Between the Parietal Cortex and Task Switching: Transcranial Direct Current Stimulation Combined with an Event-related Potential Study

Task switching refers to a set of cognitive processes involved in shifting attention from one task to another. In recent years, researchers have applied transcranial direct current stimulation (tDCS) to investigate the causal relationship between the parietal cortex and task switching. However, results from available studies are highly inconsistent. This may be due to the unclear understanding of the underlying mechanisms. Therefore, the current study utilized event-related potential (ERP) analysis to investigate the modulatory effects of tDCS on task-switching processes. Twenty-four subjects were recruited to perform both predictable and unpredictable parity/magnitude tasks under anodal (RA) and sham conditions. The results showed no significant changes in behavioral performance. However, marked tDCS-induced ERP changes were observed. Specifically, for the predictable task switching, compared with the sham condition, the target-N2 component occurred significantly earlier for switch trials than repeat trials under the RA condition in males, while no difference was found in females. For unpredictable task switching, under the sham condition, the P2 peak was significantly larger for switch trials compared with repeat trials, whereas this difference was not observed under the RA condition. These results indicated the causal relationship between the right parietal cortex and exogenous adjustment processes involved in task switching. Moreover, anodal tDCS over the right parietal cortex may lead to the manifestation of gender differences.

Automated HEART score determination via ChatGPT: Honing a framework for iterative prompt development.

This study presents a design framework to enhance the accuracy by which large language models (LLMs), like ChatGPT can extract insights from clinical notes. We highlight this framework via prompt refinement for the automated determination of HEART (History, ECG, Age, Risk factors, Troponin risk algorithm) scores in chest pain evaluation. We developed a pipeline for LLM prompt testing, employing stochastic repeat testing and quantifying response errors relative to physician assessment. We evaluated the pipeline for automated HEART score determination across a limited set of 24 synthetic clinical notes representing four simulated patients. To assess whether iterative prompt design could improve the LLMs' ability to extract complex clinical concepts and apply rule-based logic to translate them to HEART subscores, we monitored diagnostic performance during prompt iteration. Validation included three iterative rounds of prompt improvement for three HEART subscores with 25 repeat trials totaling 1200 queries each for GPT-3.5 and GPT-4. For both LLM models, from initial to final prompt design, there was a decrease in the rate of responses with erroneous, non-numerical subscore answers. Accuracy of numerical responses for HEART subscores (discrete 0-2 point scale) improved for GPT-4 from the initial to final prompt iteration, decreasing from a mean error of 0.16-0.10 (95% confidence interval: 0.07-0.14) points. We established a framework for iterative prompt design in the clinical space. Although the results indicate potential for integrating LLMs in structured clinical note analysis, translation to real, large-scale clinical data with appropriate data privacy safeguards is needed.

Trial of labor after cesarean: Maternal and neonatal outcomes from the Consortium on Safe Labor.

The aim of our study is to describe maternal and neonatal morbidity and mortality in patients undergoing trial of labor after cesarean from the Consortium on Safe Labor. This was a secondary analysis of the Consortium on Safe Labor database, a retrospective cohort study over a 7 year study period. Maternal and neonatal outcomes were evaluated based on desired delivery mode: planned elective repeat cesarean delivery or trial of labor after cesarean. Of 9858 patients in our analysis, our study population had 4400 patients (45%) who desired trial of labor after cesarean and 5458 patients (55%) who desired elective repeat cesarean delivery. Women who attempted trial of labor after cesarean compared to those who had an elective repeat cesarean delivery were more likely to have an obstetric hemorrhage (adjusted odds ratio 1.6; 95% CI 1.3 -2.0) and blood transfusion (adjusted odds ratio 2.3; 95% CI 1.6 -3.2). Maternal morbidity in women undergoing trial of labor after cesarean was predominantly hemorrhage-related.

Frontal P300 asymmetry and congruence judgment: Retroactive switching is impaired during school day mornings in female adolescents

Investigating frontal EEG asymmetry as a possible biomarker of cognitive control abilities is especially important in ecological contexts such as school and work. We used a novel approach combining judgment performance and hemispheric frontal event-related potential (ERP) P300 asymmetry (fP3As) to evaluate aspects of cognitive control (i.e., repetition and switching) in adolescent females over a two-week ordinary school period. While undergoing electroencephalographic recording, students performed a word-colour “Stroop-like” congruence judgment task during morning and afternoon sessions, on Mondays and Wednesdays. Proportion of incongruence and congruence trials was 75% and 25%, respectively. ERP analysis revealed larger “novelty” right hemispheric fP3As amplitude for infrequent congruence but equivalent or significantly smaller than left hemispheric fP3As amplitude for frequent incongruence. RTs increased with extent of right fP3As shift. Behaviorally, repeat trial pairs (i.e., congruent followed by congruent, incongruent followed by incongruent) generally did not differ by time or day and were associated with near-ceiling accuracy. In contrast, switch trial pairs (i.e., congruent followed by incongruent, incongruent followed by congruent) in the afternoon were slower and associated with lower accuracy at the expected 75% criterion rate (i.e., judging incongruence by default), dropping significantly below 75% in the mornings. Crucially, compared to afternoon, morning fP3As patterns did not change adaptively with switch trial pairs. Although retroactive switching during congruence judgment was affected at all testing times, we conclude it was most impaired in the mornings of both early and mid school weeks, supporting misalignment between adolescent circadian cycle and school start time. We discuss some implications for optimal learning of adolescents at school.

PRACTICE EFFECTS ON BRAIN EFFICIENCY OF WALKING IN AGING AND NEUROLOGICAL DISEASE

Abstract Evidence provides support for using functional near-infrared spectroscopy (fNIRS) to quantify brain activations, notably in the pre-frontal cortex (PFC), under different walking conditions. Dual-tasks that involve walking impose additional demands on attention resources relative to the single tasks, and Studies using fNIRS revealed increased HbO2 in the PFC in Dual-Task-Walk (DTW) compared to Single-Task-Walk (STW) conditions in several populations. Burst measurement within session, which involves repeated administration of the same task, affords evaluation of short-term practice effects on changes in walking performance and the efficiency of its underlying neural activation. Here, we examined the effects of task (STW vs. DTW) and burst measurement (three counter-balanced repeated trials of each task condition) on walking performance and fNIRS-derived HbO2 in the PFC in older adults with multiple sclerosis (n=80, %female=65%, mean age=64ys) and controls (n=79, %female=65, mean age=69ys). Participants were enrolled in an ongoing cohort study designed to determine cognitive and brain predictors of locomotion in older adults with MS. Results from linear mixed effects models (LMEMs) revealed: 1) higher fNIRS-derived HbO2 in DTW compared to STW (p&amp;lt;.01). 2) fNIRS-derived HbO2 levels declined over repeated trials, notably in DTW (p&amp;lt;.01). 3) gait velocity was slower in DTW compared to STW (p&amp;lt;.01). 4) gait velocity improved over repeated trials (p&amp;lt;.01). The combination of decline in fNIRS-derived HbO2 levels and faster walking over repeated trials under DTW suggests more efficient usage of brain resources to support attention-demanding locomotion in aging and neurological disease.

Left superior parietal lobe mediates the link between spontaneous mind-wandering tendency and task-switching performance

While increasing studies have documented the link between mind wandering and task switching, less is known about which brain regions mediate this relationship. Using the MPI-Leipzig Mind-Brain-Body dataset (N = 173), we investigated the association between trait-level tendencies of mind wandering, task-switching performance, structural connectivity, and resting-state functional connectivity. At the behavioral level, we found that higher spontaneous mind-wandering trait scores were associated with shorter reaction times on both repeat and switch trials. The whole brain cortical thickness analysis revealed a strong mediating role of the left superior parietal lobe, which is part of the dorsal attention network, in the link between spontaneous mind-wandering tendency and task-switching performance. The resting-state functional connectivity analysis further demonstrated that this association was partly mediated by the negative dorsal attention network-default mode network functional connectivity. No significant mediating effects were found for deliberate mind-wandering tendency. Overall, the findings highlight the pivotal role of the left superior parietal lobe in activating new mental set during mind-wandering and task-switching processes, providing another evidence in favor of a role for switching in mind wandering.

An Experimental Approach to Induce Trips in Lower-Limb Amputees.

Reestablishing balance after a trip is challenging for lower-limb amputees and often results in a fall. The effectiveness of reestablishing balance following a trip depends on factors such as amputation level (transtibial or transfemoral) or which limb is tripped (prosthetic or sound/lead or trailing). Understanding the recovery responses can help identify strategies to avoid a trip becoming a fall and what trip-response functionality could be designed into a prosthesis. This study presents an experimental approach for inducing unexpected trips in individuals with amputation. Tripping was manually triggered by activating an electromagnetic device to raisea polypropylene wire to obstruct (bring to a near halt) theswinging limb during its mid-swing phase. A safety harness attached to a ceiling rail ensured participants did not hit the ground if they failed to reestablish balance following the trip (i.e., it prevented a fall from occurring). One transtibial amputee completed repeated walking trials in which a trip was induced around 1 out of 15 times to avoid it being anticipated. 3D kinematics were determined via two smartphones (60Hz) using the OpenCap software, highlighting that the experimental approach induced meaningful tripping/recovery responses dependent on which limb was tripped (prosthetic or sound). The presented methodology avoids using a rigid obstacle, potentially reducing the risk of injuries, and is inexpensive and easy to set up. Importantly it permits a trip to be unexpectedly introduced during the mid-swing phase of the gait and hence provides an approach for identifying real-world trip recovery responses. When tripping the sound limb, participants could 'disentangle' from the trip-wire (post-trip) by plantarflexing the ankle, but such action was not possible when tripping the prosthetic limb.