Slower Reaction Times Research Articles

Interference and Facilitation Effects on Stroop‐like Tasks in Older Adults

AbstractBackgroundThe effect of aging on susceptibility to interference on Stroop‐like tasks is not clearly understood. Some previous studies have suggested slowed reaction time explains age‐related diminution on Stroop performance, while more recent meta‐analyses suggest that disproportionate interference effects are seen with aging, regardless of slower reaction times. In addition, other variables such as education and IQ have been suggested to mediate Stroop‐like effects in older participants.MethodIn the current study, we assessed the relationship between age and Stroop effects in 348 participants, aged 40‐89, with a wide range of educational achievement. The Stroop tasks were administered as part of a novel computerized neuropsychological battery that utilizes advanced automatic speech recognition and transcription software, the California Cognitive Assessment Battery (CCAB). We are currently utilizing the CCAB to track changes in cognition associated with aging, including evolution of mild cognitive impairment (MCI) and dementia, in an ongoing longitudinal study.ResultMultiple regression analysis showed that age independently predicted both Stroop interference (incongruent minus neutral response times) and facilitation effects (neutral minus congruent response times). However, other variables including gender and vocabulary also independently predicted Stroop facilitation, while gender also independently predicted Stroop interference.ConclusionIn summary, while aging has a significant impact on interference and facilitation effects on Stroop‐like tasks, additional variables such as gender and vocabulary (a proxy for IQ) also play a role in performance on these measures of selective attention.

Altered electrophysiology mechanism related to inhibitory control in adults with insomnia

BackgroundInsomnia disorder (ID), one of the most common psychophysiological disorders, can cause a serious burden on the individual's work and academic performance. Cognitive dysfunction often exists in patients with insomnia, which negatively affects their living quality. Inhibitory control (IC), as a vital cognitive function, allows individuals to suppress attention, behavior, or thoughts that are irrelevant to the task, so as to effectively adapt to the current goal. The earlier studies on the inhibitory control of insomnia patients predominantly used subjective scales for evaluation and that can have drawbacks because they don't provide an objective assessment.MethodsIn order to investigate the inhibitory control function of insomniacs, this research subdivides inhibitory control into response inhibition and conflict inhibition. The response inhibition and conflict inhibition capacities of insomniacs were evaluated using the two-choice oddball task and the color-word stroop task, and accordingly the association between insomnia disorder and inhibitory control capacity as well as its cognitive neural mechanism was able to be examined.ResultsBehavioral results finding, insomniacs conducted the two-choice oddball test and the color-word stroop task with lower accuracy and slower reaction times when compared to healthy sleepers. ERP results finding, when performing the two-choice oddball task, the P3 amplitude of the insomniacs was significantly lower than that of healthy sleepers while there was no significant difference between the two groups' N2 amplitudes. At the same time, when completing the color-word stroop task, the insomniacs' N450 amplitude was significantly lower than that of healthy sleepers.DiscussionThe above findings suggest that in response inhibition tasks, insomniacs may have weaker motor inhibition abilities, and similarly perform weaker conflict monitoring abilities in conflict inhibition tasks, which indicates that insomniacs' inhibitory control is impaired compared to that of healthy sleepers. This study thus relates to the finding at the electrophysiological level that there is a certain correlation between insomnia and a decline in inhibitory control ability, which may suggest that improving inhibitory control function in patients with insomnia is a clinically significant and worthwhile area of adjuvant treatment.

The effects of emotional stimuli on Word retrieval in people with aphasia

PurposePrior studies have shown that people with aphasia (PWA) have demonstrated superior language performance for emotional compared to nonemotional stimuli on a range of tasks, including auditory comprehension, verbal pragmatics, repetition, reading, and writing. However, studies on word retrieval, specifically, have suggested a possible interference effect of emotion on naming. The purpose of this study was to examine the effect of the emotional valence of stimuli on word retrieval in a series of naming tasks in PWA. MethodThirteen PWA and 13 neurotypical controls participated in four single-word naming tasks, including 1) object picture naming, 2) action picture naming, 3) category-member generation, and 4) verb generation. Each task included three valence sets of positively-, negatively-, and neutrally-rated pictures or words, which were obtained from the standardized International Affective Picture System (Lang et al., 2008) and the Affective Norms for Emotional Words (Bradley and Lang, 1999) databases. Accuracy and reaction time (RT) were measured and compared across groups, tasks, and valence sets. ResultsEmotional stimuli, especially negative stimuli, resulted in worse naming performance, as measured by accuracy and RT, compared to nonemotional stimuli in PWA and neurotypical controls. This effect was relatively robust across the four naming tasks. In most cases, negative stimuli resulted in lower accuracy and slower RT than positive stimuli. ConclusionsThese findings suggest that stimulus valence may interfere with word retrieval for PWA and neurotypical adults and that this effect is robust across different types of naming tasks that vary by word class (nouns versus verbs) and stimulus type (pictures versus words). Negative stimuli resulted in worse naming performance than positive stimuli. These results suggest that emotionality of stimuli is an important variable to consider in word retrieval research.

Linking tonic and phasic pupil responses to P300 amplitude in an emotional face-word Stroop task.

The locus coeruleus-norepinephrine (LC-NE) system, which regulates arousal levels, is important for cognitive control, including emotional conflict resolution. Additionally, the LC-NE system is implicated in P300 generation. If the P300 is mediated by the LC-NE system, and considering the established correlations between LC activity and pupil dilation, P300 amplitude should correlate with task-evoked (phasic) pupil dilation on a trial-by-trial basis. However, prior studies, predominantly utilizing oddball-type paradigms, have not demonstrated correlations between concurrently recorded task-evoked pupil dilation and P300 responses. Using a recently developed emotional face-word Stroop task that links pupil dilation to the LC-NE system, here, we examined both intra- and inter-individual correlations between task-evoked pupil dilation and P300 amplitude. We found that lower accuracy, slower reaction times, and larger task-evoked pupil dilation were obtained in the incongruent compared to the congruent condition. Furthermore, we observed intra-individual correlations between task-evoked pupil dilation and P300 amplitude, with larger pupil dilation correlating with a greater P300 amplitude. In contrast, pupil dilation did not exhibit consistent correlations with N450 and N170 amplitudes. Baseline (tonic) pupil size also showed correlations with P300 and N170 amplitudes, with smaller pupil size corresponding to larger amplitude. Moreover, inter-individual differences in task-evoked pupil dilation between the congruent and incongruent conditions correlated with differences in reaction time and P300 amplitude, though these effects only approached significance. To summarize, our study provides evidence for a connection between task-evoked pupil dilation and P300 amplitude at the single-trial level, suggesting the involvement of the LC-NE system in P300 generation.

Central Bank Rate Pass-Through Effects on Kenya’s Lending Rate

Several African nations, including Kenya, Nigeria, and South Africa, have seen dramatic shifts in their monetary policy framework and financial environment during the last two decades. To manage and stabilize the economy, the Central Bank of Kenya (CBK) stopped intervening directly in lending low interest rates at financial institutions and instead turned to indirect and market-based measures to carry out monetary policy. Even though it was predictable that a changing financial environment would have a substantial impact on the efficacy of monetary policies, there has not been sufficient research done to determine how IRPT affects lending rates. The purpose of this article was to analyze the pass-through effects of the central bank rate on lending rates in Kenya. The study adopted a non-experimental research design. Data was collected from the CBK, the Kenya Bureau of National Statistics, and the Nairobi Stock Exchange between 2010 and 2021 quarterly data. The study's theoretical underpinning was the loanable funds theory and cost of capital. The cost-of-funds method is based on the conventional marginal cost pricing model for financial markets and helps explain how market prices are transmitted to consumers. The error correction model was used to measure the short-term effect of bank rate changes on Kenyan lending rates. The findings showed that Kenya has an incomplete IRPT which means that increases in the lending rate would be less than proportional whenever there is a change of a specific percentage in the CBR. According to the study, this may be one of the causes of some banks' foreign ownership, their independence from the central bank's liquidity, and their slow reaction times to signals from the central bank to modify lending rates. The study recommends that since commercial banks are a very important component in the transmission mechanisms, they should follow suit in the adjustment of the lending rates.

EMG measured reaction time as a predictor of invalid symptom report in psychosomatic patients

Background: Symptom validity tests (SVTs) and performance validity tests (PVTs) are important tools in sociomedical assessments, especially in the psychosomatic context where diagnoses mainly depend on clinical observation and self-report measures. This study examined the relationship between reaction times (RTs) and scores on the Structured Inventory of Malingered Symptomatology (SIMS). It was proposed that slower RTs and larger standard deviations of reaction times (RTSDs) would be observed in participants who scored above the SIMS cut-off (>16). Methods: Direct surface electromyography (EMG) was used to capture RTs during a computer-based RT test in 152 inpatients from a psychosomatic rehabilitation clinic in Germany. Correlation analyses and Mann-Whitney U were used to examine the relationship between RTs and SIMS scores and to assess the potential impact of covariates such as demographics, medical history, and vocational challenges on RTs. Therefore, dichotomized groups based on each potential covariate were compared. Results: Significantly longer RTs and larger RTSDs were found in participants who scored above the SIMS cut-off. Current treatment with psychopharmacological medication, diagnosis of depression, and age had no significant influence on the RT measures. However, work-related problems had a significant impact on RTSDs. Conclusion: There was a significant relationship between longer and more inconsistent RTs and indicators of exaggerated or feigned symptom report on the SIMS in psychosomatic rehabilitation inpatients. Findings from this study provide a basis for future research developing a new RT-based PVT.

O031 The Inter-stimulus Interval Effect in the Psychomotor Vigilance Task

Abstract Introduction The Psychomotor Vigilance Task (PVT) is a widely used measure of the effects of sleep deprivation on vigilant attention. The test requires a rapid response to a stimulus occurring at random inter-stimulus intervals (ISIs) between 2 and 10 seconds following a previous response. A few studies have found an ISI effect where shorter ISIs (2-4s) have slower reaction times (RTs) than longer ISIs (8-10s). How this ISI effect is impacted by circadian timing has yet to be investigated. Method This study compared the ISI effect at 3 time points coinciding with 5, 23 (circadian trough), and 29 hours of wakefulness. Data were taken from 16 healthy participants during a 30 hour period of sleep deprivation. Results A repeated-measures (3 x 3) ANOVA (3 time points, 3 ISIs) found that RTs were slower and lapses (RT>500msec) more frequent in short ISIs compared with medium and long ISIs. RTs were also slower and lapses more frequent at the circadian trough compared to both the early testing session and after 29h of total sleep deprivation. Discussion Increased lapses in shorter ISIs could be explained by an involuntary mental “rest period” after responding, that gets longer and more frequent under sleep pressure from both circadian and homeostatic sleep pressure. These findings have implications for interpreting PVT results and their application to everyday tasks, such as driving. Further research could involve neuroimaging the brain’s responses during different ISIs to confirm the mental ‘rest period’ following a response in the PVT task.

B - 03 Inhibitory Control and Saccadic Eye Movement in Adults with Attention-Deficit Hyperactivity Disorder: an Eye-Tracking Analysis.

The objective of this study was to investigate oculomotor differences between adults with and without attention-deficit hyperactivity disorder (ADHD) during a computerized response inhibition task, utilizing eye-tracking technology. Twenty-nine adults with ADHD and 35 controls (ages 18-32) were recruited from Sona Systems and the Learning Center at a university. Participants completed 120 randomized trials of the flanker task while their eye movements were monitored. Saccadic eye movement was investigated, while reaction time and performance errors were recorded from the flanker task. Participants with ADHD were required to refrain from taking stimulant medication the day of the experiment. A linear mixed-effects regression model was fitted. Having ADHD resulted in significantly slower response times, t(57) = 2.73, p < 0.005, 95% CI [0.04, 0.27], but not significantly more errors than control participants on the flanker task. There were no significant differences in the number of saccades between groups. Further analysis demonstrated that adults with ADHD had a significantly higher number of saccades as the number of trials increased, t(7019) = 3.69, p < 0.001, 95% CI [0.00105, 0.00314]. Slower reaction time in adults with ADHD during the flanker task indicates slower processing, but this did not affect their accuracy. While no differences were found in the number of saccades between groups, higher saccades as trial number increased in adults with ADHD suggests possible fatigue contributing to oculomotor differences. Further research is necessary to investigate potential gaze differences during a task that necessitates increased saccadic eye movement.

Delayed and More Variable Unimanual and Bimanual Finger Tapping in Alzheimer's Disease: Associations with Biomarkers and Applications for Classification.

Despite reports of gross motor problems in mild cognitive impairment (MCI) and Alzheimer's disease (AD), fine motor function has been relatively understudied. We examined if finger tapping is affected in AD, related to AD biomarkers, and able to classify MCI or AD. Forty-seven cognitively normal, 27 amnestic MCI, and 26 AD subjects completed unimanual and bimanual computerized tapping tests. We tested 1) group differences in tapping with permutation models; 2) associations between tapping and biomarkers (PET amyloid-β, hippocampal volume, and APOEɛ4 alleles) with linear regression; and 3) the predictive value of tapping for group classification using machine learning. AD subjects had slower reaction time and larger speed variability than controls during all tapping conditions, except for dual tapping. MCI subjects performed worse than controls on reaction time and speed variability for dual and non-dominant hand tapping. Tapping speed and variability were related to hippocampal volume, but not to amyloid-β deposition or APOEɛ4 alleles. Random forest classification (overall accuracy = 70%) discriminated control and AD subjects, but poorly discriminated MCI from controls or AD. MCI and AD are linked to more variable finger tapping with slower reaction time. Associations between finger tapping and hippocampal volume, but not amyloidosis, suggest that tapping deficits are related to neuropathology that presents later during the disease. Considering that tapping performance is able to differentiate between control and AD subjects, it can offer a cost-efficient tool for augmenting existing AD biomarkers.

Driving performance acutely after mTBI among young drivers

ObjectiveMild traumatic brain injury (mTBI) can impair executive function, learning, and memory, which can negatively impact driving ability. However, little is known how the driving performance of young drivers may be impacted acutely after mTBI. This study aimed to evaluate simulated driving within 96 h of mTBI among young drivers as compared to matched healthy controls, and assess the effects of increased cognitive load on driving performance. MethodsInjured young drivers ages 16 to 24 with physician-confirmed mTBI were enrolled from two sites (University of Alabama at Birmingham and Ohio State University) and completed the assessment on a high-fidelity driving simulator within 96 h of injury. Matched healthy controls were young drivers without mTBIs matched with an index mTBI by age, sex, athlete status, and driving experience. Participants drove four scenarios in a 2x2 design: with/without cognitive load and with/without critical events. Linear mixed models were used to compare the driving outcomes between mTBI drivers and healthy controls. ResultsA total of 38 participants were included, with 25 cases and 13 controls. Standard deviation of lateral position, following distance and reaction time were analyzed. The preliminary findings indicated that mTBI drivers tended to maintain more distance to the car in front of them than healthy controls. High cognitive load was associated with slower reaction time regardless of TBI status. ConclusionsThis study is the first to assess simulated driving performance among young drivers with mTBI acutely post-injury. The findings will have important clinical implications on when young drivers may return to driver post-mTBI and at what conditions. Additional research is warranted to confirm these results.

Are Warnings Suitable for Presentation in Head-Up Display? A Meta-Analysis for the Effect of Head-Up Display Warning on Driving Performance

Head-up display (HUD) warnings are gaining increasing attention with the growing importance of advanced warning systems in vehicles for improving driving safety. However, the effectiveness of HUD warnings is still controversial considering the various driving performance indexes, warning modalities, and driving scenarios used in previous studies. This study conducts meta-analyses of the relevant literature to examine whether HUD warnings (both unimodal HUD warnings and multimodal warnings with HUD) have advantages compared with other warnings (head-down display warnings, auditory warnings, tactile warnings, and multimodal warnings without HUD) for driver reaction times and driving quality. Overall, 33 articles were included in four meta-analyses. Additionally, the effects of the related moderator variables of scenario, mapping of warnings, and non-driving-related tasks (NDRTs) on the relationship between using HUD warnings and using non-HUD warnings was analyzed. The results show that using unimodal HUD warnings leads to faster reaction times compared with head-down display warnings but has no significant advantage on driving performance over auditory warnings in general and results in slower reaction times than using tactile warnings. However, results of the moderating effects suggest that using HUD warnings in non-critical scenarios and using high mapping HUD icons (i.e., HUD warnings with specific hazard information) are conducive to improving driving performance in comparison with other warning types. These results highlight the potential advantages of HUD in transmitting warning information. The future application and design of HUD warnings may need to focus on specific situations considering iconic mapping to an event.

Movement-related beta and gamma oscillations indicate parallels and disparities between Alzheimer's disease and HIV-associated neurocognitive disorder

People with HIV (PWH) often develop HIV-related neurological impairments known as HIV-associated neurocognitive disorder (HAND), but cognitive dysfunction in older PWH may also be due to age-related disorders such as Alzheimer's disease (AD). Discerning these two conditions is challenging since the specific neural characteristics are not well understood and limited studies have probed HAND and AD spectrum (ADS) directly. We examined the neural dynamics underlying motor processing during cognitive interference using magnetoencephalography (MEG) in 22 biomarker-confirmed patients on the ADS, 22 older participants diagnosed with HAND, and 30 healthy aging controls. MEG data were transformed into the time-frequency domain to examine movement-related oscillatory activity and the impact of cognitive interference on distinct stages of motor programming. Both cognitively impaired groups (ADS/HAND) performed significantly worse on the task (e.g., less accurate and slower reaction time) and exhibited reductions in frontal and cerebellar beta and parietal gamma activity relative to controls. Disease-specific aberrations were also detected such that those with HAND exhibited weaker gamma interference effects than those on the ADS in frontoparietal and motor areas. Additionally, temporally distinct beta interference effects were identified, with ADS participants exhibiting stronger beta interference activity in the temporal cortex during motor planning, along with weaker beta interference oscillations dispersed across frontoparietal and cerebellar cortices during movement execution relative to those with HAND. These results indicate both overlapping and distinct neurophysiological aberrations in those with ADS disorders or HAND in key motor and top-down cognitive processing regions during cognitive interference and provide new evidence for distinct neuropathology.

Low thalamic activity during a digit-symbol substitution task is associated with symptoms of subjective cognitive decline.

Subjective cognitive decline (SCD) may represent the earliest preclinical stage of Alzheimer's Disease (AD) for some older adults. However, the underlying neurobiology of SCD is not completely understood. Since executive function may be affected earlier than memory function in the progression of AD, we aimed to characterize SCD symptoms in terms of fMRI brain activity during the computerized digit-symbol substitution task (DSST), an executive function task. We also explored associations of DSST task performance with brain activation, SCD severity, and amyloid-ß (Aß) load. We analyzed data from 63 cognitively normal older individuals (mean age 73.6 ± 7.2) with varying degree of SCD symptoms. Participants completed a computerized version of DSST in the MR scanner and a Pittsburgh Compound-B (PiB)-PET scan to measure global cerebral Aß load. A voxel-wise analysis revealed that greater SCD severity was associated with lower dorsomedial thalamus activation. While task performance was not associated with brain activation nor Aß load, slower reaction time was associated with greater SCD severity. The observed lower dorsomedial thalamus activation may reflect declining familiarity-based working memory and the trans-thalamic executive function pathway in SCD. SCD symptoms may reflect altered neural function and subtle decline of executive function, while Aß load may have an indirect impact on neural function and performance. Self-perceived cognitive decline may serve as a psychological/subjective marker reflecting subtle brain changes.

Comparing mouse versus trackpad input in a web-based app for assessing motor learning

Current laboratory approaches to measuring motor learning are not accessible to all populations, limiting research about developmental processes and medical conditions that impact motor control. We recently created a web-based application remote assessment of visuomotor adaptation, a gold-standard approach to studying motor learning. Previously, we validated this application in younger and older adults. However, preliminary analyses suggested that the input device (mouse or trackpad) may have impacted performance. The current study directly evaluated performance differences in younger adults using the application with a mouse compared to a trackpad. Results showed no statistically significant differences in learning curves or movement times between groups, but reaction time was significantly faster in mouse users. While the input device had very little impact on motor learning, slower reaction time when using a trackpad may be related to increased cognitive demands or reduced movement efficiency compared to using a mouse for this task.

Where is an emotion? Using an emotional spatial cueing task to test for emotional localization following targeted visceroception.

The relationship between emotion and attention is vital for adaptation. Trained attention to bodily sensations can heighten emotional awareness, including during "visceroception" (sensing the viscera, principally the heart, lungs and gut), which has been linked to emotion intensity and regulation. However, it is not always clear when bodily attention is adaptive, and useful to maintain, or maladaptive and best inhibited. The current study, part of a wider exploratory project, investigates "localized emotion" in this context. Localized emotion is a novel construct, articulated within the project, and suggested to be manifested within a visceroceptive system: targeted visceroception could result in disinhibited attention to localized emotion. In particular, whilst evidence points to the importance of the gastrointestinal tract for emotion (e.g., gut biome, enteric nervous system), gut sensations are often barely detectable, consistent with an inhibition process. An emotional spatial cueing task was used to test for localized effects within several groups: one trained for 8 weeks to focus on their lower abdomen (gastroception), with another focused on their chest cavity (cardioception), plus a control group. The spatial cueing task involved rapid responding to the detection of bodily feelings following the presentation of an emotional picture. Participants then indicated on a body map where they had detected the feeling, followed by corresponding valence and arousal levels (i.e., core affect) on a self-assessment manikin. Data were analyzed using generalized estimating equations. There was some support for localization in the gastroception group relative to the chest-focused group and controls. Gastroception-related findings included: greater improvement in interoception (interoceptive sensibility), slowed reaction times, a cluster of lower abdominal detections on a body map, changes in core affect, and indications of improved emotion regulation. Attending to the gut may play a key role in improving one's ability to access emotional feeling, with associated implications for emotion regulation.

Aqueous Calcium Phosphate Cement Inks for 3D Printing

Mimicking the native properties and architecture of natural bone is a remaining challenge within the field of regenerative medicine. Due to the chemical similarity of calcium phosphate cements (CPCs) to bone mineral, these cements are well studied as potential bone replacement material. Nevertheless, the processing and handling of CPCs into prefabricated pastes with adequate properties for 3D printing has drawbacks due to slow reaction times, limited design freedom, as well as fabrication issues such as filter pressing during ejection through thin nozzles. Herein, an aqueous cement paste containing α‐tricalcium phosphate powder is proposed, which is stabilized by sodium pyrophosphate (Na4P2O7·10H2O) as additive. Since high powder loadings within pastes can result in filter pressing during extrusion, various concentrations and molecular weights of hyaluronic acid (HyAc) are added to the cement paste, resulting in reduced filter pressing during 3D extrusion‐based printing. These cement pastes are investigated regarding their setting reaction after activation with orthophosphate solution by isothermal calorimetry and X‐ray diffraction, as well as their hardening performance using Imeter measurements, while the processability is assessed by extrusion through 1.2 and 0.8 mm cannulas. The 3D‐printed structures with appropriate HyAc molecular weight and concentration demonstrate suitable mechanical properties and resolution for clinical application.

The power of (surreptitiously) mentioning your mentor’s name: Subliminal priming of mentor’s name modulates N170 responses to blurred faces

Using the event-related potentials (ERPs) technique and subliminal priming paradigm, the present study examined the influence of mentioning a mentor’s name on graduate students. Fifty-eight graduate students were subliminally primed by mentor and stranger names before making pressure judgments of a series of unrelated blurred facial photos with neutral emotion. The face-sensitive N170 components were analyzed according to the pressure judgment × name prime conditions. The results showed that relative to stranger names, subliminal priming of mentor’s name could modulate students’ N170 reactions during facial processing. Specifically, the mentor-name priming attenuated N170 amplitudes for high-pressure judgment trials on the right hemisphere but heightened the overall N170 responses on the left hemisphere. Behavioral results also showed that the mentor-name priming slowed students' reaction time during pressure judgments; in addition, students’ attitudes towards mentors were correlated with N170 amplitudes on high-pressure judgment conditions. These findings provided neuroscientific evidence demonstrating the psychological significance of mentors to graduate students. Theoretical and practical implications were also discussed.

Single-Leg Hop Stabilization Throughout Concussion Recovery: A Preliminary Biomechanical Assessment.

Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration-deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7d) and when asymptomatic (≤72h of symptom resolution). Prospective, cohort laboratory study. Ten concussed (60% male; 19.2 [0.9]y; 178.7 [14.0]cm; 71.3 [18.0]kg) and 10 matched controls (60% male; 19.5 [1.2]y; 176.1 [12.6]cm; 71.0 [17.0]kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6's or 7's) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task. We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03N·m/body weight; P = .048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09s; P = .015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥ .051). Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research.

On-Field and Pitch-Side (Sideline) Assessment of Sports Concussion in Collision Sports: An Expert Consensus Statement Using the Modified Delphi Technique

To perform a Delphi consensus for on-field and pitch-side assessment of sports-related concussion (SRC). Open-ended questions in rounds 1 and 2 were answered. The results of the first 2 rounds were used to develop a Likert-style questionnaire for round 3. If agreement at round 3 was ≤80% for an item, if panel members were outside consensus, or there were >30% neither agree/disagree responses, the results were carried forward into round 4. The level of agreement and consensus was defined as 90%. Loss of consciousness (LOC) or suspected LOC, motor incoordination/ataxia, balance disturbance, confusion/disorientation, memory disturbance/amnesia, blurred vision/light sensitivity, irritability, slurred speech, slow reaction time, lying motionless, dizziness, headaches/pressure in the head, falling to the ground with no protective action, slow to get up after a hit, dazed look, and posturing/seizures were clinical signs of SRC and indicate removal from play. Video assessment is helpful but should not replace clinical judgment. LOC/unresponsiveness, signs of cervical spine injury, suspicion of other fractures (skull/maxillo-facial), seizures, Glasgow Coma Scale score <14 and abnormal neurologic examination findings are indications for hospitalization. Return to play should only be considered when no clinical signs of SRC are present. Every suspected concussion should be referred to an experienced physician. Consensus was achieved for 85% of the clinical signs indicating concussion. On-field and pitch-side assessment should include the observation of the mechanism, a clinical examination, and cervical spine assessment. Of the 19 signs and red flags requiring removal from play, consensus was reached for 74%. Normal clinical examination and HIA with no signs of concussion allow return to play. Video assessment should be mandatory for professional games but should not replace clinical decision-making. Sports Concussion Assessment Tool, Glasgow Coma Scale, vestibular/ocular motor screening, Head Injury Assessment Criteria 1, and Maddocks questions are useful tools. Guidelines are helpful for non-health professionals. Level V, expert opinion.

Improved performance in temperature and speed of TCP artificial muscles for soft wearables robots by length modification

Artificial muscles provide a unique solution for wearable rehabilitation robots (WRRs) because they are compliant, compact, and lightweight. Twisted and coiled polymer actuators (TCPs) are artificial muscles from thermally activated polymer fibres. They present high power density, linearity, stress and strain compared to other artificial muscles. Nevertheless, as TCPs require heat to start, their main barrier for widespread use in WRRs are their slow reaction times and the high temperatures they reach. Previous studies have analysed different parameters, like fibre material, fibre diameter, and various cooling systems, to improve TCP frequency response and working temperature. Nevertheless, the length of the actuator has not been explored as a possible parameter to enhance the actuation performance in this regard. This work focuses on studying the behaviour of TCPs with different lengths and how the performance in frequency response and temperature can be improved using the length as a primary parameter, as they are critical for wearable robots. First, a characterisation of the TCPs was performed. Then, a method to improve frequency response, based on offsets on long actuators was implemented and validated using a chirp signal. The experimental results show that the mechanical characteristics are similar regardless of the actuator’s length. They reached a strain of 10% with a power of 0.16 W cm−1. However, the electrothermal properties changed as the power needed to increase temperature was higher when the actuator was enlarged. Therefore, an improvement in the required temperature was found, able to reduce the temperature with the same frequency response. Regarding the technique to enhance the speed of the actuator, it was possible to increase the frequency by 0.0006 Hz for each mm applied as an offset. Hence, the frequency response for the same displacement was increased linearly as the actuator was elongated.