Construction of Ag-Co(OH)2 Tandem Heterogeneous Electrocatalyst Induced Aldehyde Oxidation and the Co-Activation of Reactants for Biomass Effective and Multi-Selective Upgrading

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides a feasible way for high value utilization of biomass resources. However, how to regulate the selective synthesis of multiple value-added products is still a great challenge. Cobalt-based compound is a promising catalyst due to its direct and indirect oxidation properties, but its weak adsorption capacity restricts its further development. Herein, by constructing Ag-Co(OH)2 heterogeneous catalyst, we realize the efficient and selective synthesis of 5-hydroxymethyl-2-furanoic acid (HMFCA) and 2, 5-furan dicarboxylic acid (FDCA) value-added products at different potential ranges. Based on in-situ infrared spectroscopy, quasi-operando X-ray photoelectron spectroscopy, in-situ electrochemical impedance spectroscopy, zeta potential, electrochemical measurements and density functional theory calculations, it is proved that the addition of Ag can effectively promote the oxidation of aldehyde group to carboxyl group, and then generate HMFCA at low potential. Moreover, the introduction of Ag can activate cobalt-based compound, thus strengthening the adsorption of organic molecules and OH- species, and promoting the formation of FDCA. This work achieves the selective synthesis of two value-added chemicals by one tandem catalyst and deeply analyzes the adsorption enhancement mechanism of the catalyst, which provides a powerful reference and guidance for the design and development of efficient multi-component heterogeneous catalysts. This article is protected by copyright. All rights reserved.

Movement predictability modulates sensorimotor processing

Introduction

An important factor for optimal sensorimotor control is how well we are able to predict sensory feedback from internal and external sources during movement. If predictability decreases due to external disturbances, the brain is able to adjust muscle activation and the filtering of incoming sensory inputs. However, little is known about sensorimotor adjustments when predictability is increased by availability of additional internal feedback. In the present study we investigated how modifications of internal and external sensory feedback influence the control of muscle activation and gating of sensory input.

Methods

Co-activation of forearm muscles, somatosensory evoked potentials (SEP) and short afferent inhibition (SAI) were assessed during three object manipulation tasks designed to differ in the predictability of sensory feedback. These included manipulation of a shared object with both hands (predictable coupling), manipulation of two independent objects without (uncoupled) and with external interference on one of the objects (unpredictable coupling).

Results

We found a task-specific reduction in co-activation during the predictable coupling compared to the other tasks. Less sensory gating, reflected in larger subcortical SEP amplitudes, was observed in the unpredictable coupling task. SAI behavior was closely linked to the subcortical SEP component indicating an important function of subcortical sites in predictability related SEP gating and their direct influence on M1 inhibition.

Discussion

Together, these findings suggest that the unpredictable coupling task cannot only rely on predictive forward control and is compensated by enhancing co-activation and increasing the saliency for external stimuli by reducing sensory gating at subcortical level. This behavior might serve as a preparatory step to compensate for external disturbances and to enhance processing and integration of all incoming external stimuli to update the current sensorimotor state. In contrast, predictive forward control is accurate in the predictable coupling task due to the integrated sensory feedback from both hands where sensorimotor resources are economized by reducing muscular co-activation and increasing sensory gating.

Predictors of Co-activation in Erb's Palsy: A Retrospective Study

Context

Three per thousand births have Erb's palsy. Spontaneous recovery is 50%. Co-activation yields poor outcomes. There are no objective indicators of its emergence.

Aims

Analyze if 1 month Axon Viability Index (AVI) of the axillary nerve and which active movement score (AMS) measures can predict co-activation.

Settings and Design

Tertiary level rehabilitation center, retrospective design.

Methods and Material

The electronic medical record (EMR) was reviewed for patients with Erb's palsy with Narakas grade 2 lesions, as having co-activation or not. The one-month Axillary AVI was used with monthly AMS scores. The inclusion criteria were an AVI greater than ten percent. Exclusion criteria were bi-brachial palsy, congenital anomalies, concomitant or subsequent neurological injuries, and orthopedic injuries.

Statistical Analysis Used

Descriptive statistics were used to calculate the median and interquartile values for AMS scores at each respective time point. Statistical significance for each time point was determined using a student's t-test.

Results

Regarding the t-test on the AVI data, a significant P value of 0.001 was found favoring the co-activation group. AVI of the Axillary nerve between 0.1 and 0.5 at 1 month is a reliable indicator of future development of co-activation. The following were strong indicators of the emergence of co-activation respectively: month three Wrist Extension in sitting, Shoulder Abduction in supine, Shoulder Abduction in sitting, Elbow Flexion in sitting, month six Elbow Flexion in sitting, month seven Elbow Flexion in sitting.

Conclusions

The axillary AVI at one month is a good predictor of future development of co-activation. The mentioned AMS items are the earliest indicators of co-activation.

Myoelectric interface for neurorehabilitation conditioning to reduce abnormal leg co-activation after stroke: a pilot study

Background

The ability to walk is an important factor in quality of life after stroke. Co-activation of hip adductors and knee extensors has been shown to correlate with gait impairment. We have shown previously that training with a myoelectric interface for neurorehabilitation (MINT) can reduce abnormal muscle co-activation in the arms of stroke survivors.

Methods

Here, we extend MINT conditioning to stroke survivors with leg impairment. The aim of this pilot study was to assess the safety and feasibility of using MINT to reduce abnormal co-activation between hip adductors and knee extensors and assess any effects on gait. Nine stroke survivors with moderate to severe gait impairment received six hours of MINT conditioning over six sessions, either in the laboratory or at home.

Results

MINT participants completed a mean of 159 repetitions per session without any adverse events. Further, participants learned to isolate their muscles effectively, resulting in a mean reduction of co-activation of 70% compared to baseline. Moreover, gait speed increased by a mean of 0.15 m/s, more than the minimum clinically important difference. Knee flexion angle increased substantially, and hip circumduction decreased.

Conclusion

MINT conditioning is safe, feasible at home, and enables reduction of co-activation in the leg. Further investigation of MINT's potential to improve leg movement and function after stroke is warranted. Abnormal co-activation of hip adductors and knee extensors may contribute to impaired gait after stroke.

Trial registration

This study was registered at ClinicalTrials.gov (NCT03401762, Registered 15 January 2018, https://clinicaltrials.gov/study/NCT03401762?tab=history&a=4).

Co-activation for enhanced K-ion storage in battery anodes

The relative natural abundance of potassium and potentially high energy density has established potassium-ion batteries as a promising technology for future large-scale global energy storage. However, the anodes' low capacity and high discharge platform lead to low energy density, which impedes their rapid development. Herein, we present a possible co-activation mechanism between bismuth (Bi) and tin (Sn) that enhances K-ion storage in battery anodes. The co-activated Bi-Sn anode delivered a high capacity of 634 mAh g^-1, with a discharge plateau as low as 0.35 V, and operated continuously for 500 cycles at a current density of 50 mA g^-1, with a high Coulombic efficiency of 99.2%. This possible co-activation strategy for high potassium storage may be extended to other Na/Zn/Ca/Mg/Al ion battery technologies, thus providing insights into how to improve their energy storage ability.

Practice beats age: co-activation shapes heritage speakers' lexical access more than age of onset

Probabilistic associations make language processing efficient and are honed through experience. However, it is unclear what language experience factors explain the non-monolingual processing behaviors typical of L2 learners and heritage speakers (HSs). We investigated whether AoO, language proficiency, and language use affect the recognition of Spanish stress-tense suffix associations involving a stressed syllable that cues a present suffix (SALta "s/he jumps") and an unstressed syllable that cues a past suffix (SALtó "s/he jumped"). Adult Spanish-English HSs, English-Spanish L2 learners, and Spanish monolinguals saw a paroxytone verb (stressed initial syllable) and an oxytone verb (unstressed initial syllable), listened to a sentence containing one of the verbs, and chose the one they heard. Spanish proficiency measured grammatical and lexical knowledge, and Spanish use assessed percentage of current usage. Both bilingual groups were comparable in Spanish proficiency and use. Eye-tracking data showed that all groups fixated on target verbs above chance before hearing the syllable containing the suffix, except the HSs in the oxytones. Monolinguals fixated on targets more and earlier, although at a slower rate, than HSs and L2 learners; in turn, HSs fixated on targets more and earlier than L2 learners, except in oxytones. Higher proficiency increased target fixations in HSs (oxytones) and L2 learners (paroxytones), but greater use only increased target fixations in HSs (oxytones). Taken together, our data show that HSs' lexical access depends more on number of lexical competitors (co-activation of two L1 lexica) and type (phonotactic) frequency than token (lexical) frequency or AoO. We discuss the contribution of these findings to models in phonology, lexical access, language processing, language prediction, and human cognition.

The Effects of a 12-Week-Long Sand Exercise Training Program on Neuromechanical and Functional Parameters in Type II Diabetic Patients with Neuropathy

Studies have proven the effectiveness of different weight-bearing exercise interventions for diabetic patients with neuropathy; however, several adverse effects were reported using solid surfaces. Thus, in the present study, we investigated the effects of a novel sand exercise training intervention on biomechanical and functional parameters in seven diabetic patients (age = 62.7 ± 9.7 years) with neuropathy. Patients underwent a 12-week sand exercise training program, using strengthening, stretching, balance, and gait exercises. They were tested for ankle plantar- and dorsiflexion peak torque, active range of motion (ROM), timed up and go (TUG), and bilateral static balance. EMG activity of tibialis anterior (TA), gastrocnemius medialis (GM), and lateralis (GL) muscles were measured during unilateral isometric contraction in plantar- and dorsiflexion. In the intervention period, plantarflexion peak torque improved significantly (p = 0.033), while dorsiflexion torque remained unchanged. Plantar- and dorsiflexion ROM increased (p = 0.032) and (p = 0.021), respectively. EMG activity of GM (p = 0.005) and GL (p = 0.002) measured during dorsiflexion and postural sway in the balance test, as well as time to complete the TUG test, decreased significantly (p = 0.021) and (p = 0.002), respectively. No adverse effect was reported during the intervention period. We concluded that sand exercise training can be a safe and effective method to improve plantarflexion strength, ankle flexibility, and balance, which is reflected in better gait function in patients with diabetic peripheral neuropathy (DPN).

Heterogeneous-Interface-Enhanced Adsorption of Organic and Hydroxyl for Biomass Electrooxidation

Electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) provides an efficient way to obtain high-value-added biomass-derived chemicals. Compared with other transition metal oxides, CuO exhibits poor oxygen evolution reaction performance, leading to high Faraday efficiency for HMF oxidation. However, the weak adsorption and activation ability of CuO to OH^- species restricts its further development. Herein, the CuO-PdO heterogeneous interface is successfully constructed, resulting in an advanced onset-potential of the HMF oxidation reaction (HMFOR), a higher current density than CuO. The results of open-circuit potential, in situ infrared spectroscopy, and theoretical calculations indicate that the introduction of PdO enhances the adsorption capacity of the organic molecule. Meanwhile, the CuO-PdO heterogeneous interface promotes the adsorption and activation of OH^- species, as demonstrated by zeta potential and electrochemical measurements. This work elucidates the adsorption enhancement mechanism of heterogeneous interfaces and provides constructive guidance for designing efficient multicomponent electrocatalysts in organic electrocatalytic reactions.

The Effect of Age and Fall History on Lower Extremity Neuromuscular Function During Descent of a Single Transition Step

Despite the higher injury rate of falls on steps versus level ground, few studies have examined the influence of age and fall history on step descent. The purpose of this study was to determine the lead and trail limb neuromuscular function (peak joint moments and powers, electromyographic activity) differences between young females (n = 15) and older females with (n = 15) and without (n = 15) a fall history while descending a single step. Trail limb moments and powers did not differ between groups. Lead limb sagittal plane powers at the hip and knee were greater in the young adults. Electromyographic co-activation levels (knee and ankle) were not significantly different between groups. However, peroneal activation was greater in the older groups, which may have assisted in stabilizing the ankle joint in lieu of increased co-activation at the ankle. These results demonstrate consideration of step descent is important in working with older women at risk of falls.

The effect of vibration on kinematics and muscle activation during cycling

Vibration has the potential to compromise performance in cycling. This study aimed to investigate the effects of vibration on full-body kinematics and muscle activation time series. Nineteen male amateur cyclists (mass 74.9 ± 5.9 kg, body height 1.82 ± 0.05 m, Vo2max 57 ± 9 ml/kg/min, age 27 ± 7 years) cycled (216 ± 16 W) with (Vib) and without (NoVib) vibration. Full-body kinematics and muscle activation time series were analysed. Vibration did not affect lower extremity joint kinematics significantly. The pelvic rotated with vibration towards the posterior direction (NoVib: 22.2 ± 4.8°, Vib: 23.1 ± 4.7°, p = 0.016, d = 0.20), upper body lean (NoVib: 157.8 ± 3.0°, Vib: 158.9 ± 3.4°, p = 0.001, d = 0.35) and elbow flexion (NoVib: 27.0 ± 8.2°, Vib: 29.4 ± 9.0°, p = 0.010, d = 0.28) increased significantly with vibration. The activation of lower extremity muscles (soleus, gastrocnemius lat., tibialis ant., vastus med., rectus fem., biceps fem.) increased significantly during varying phases of the crank cycle due to vibration. Vibration increased arm and shoulder muscle (triceps brachii, deltoideus pars scapularis) activation significantly over almost the entire crank cycle. The co-contraction of knee and ankle flexors and extensors (vastus med. - gastrocnemius lat., vastus med. - biceps fem., soleus - tibialis ant.) increased significantly with vibration. In conclusion vibrations influence main tasks such as propulsion and upper body stabilization on the bicycle to a different extent. The effect of vibration on the task of propulsion is limited due to unchanged lower body kinematics and only phase-specific increases of muscular activation during the crank cycle. Additional demands on upper body stabilization are indicated by adjusted upper body kinematics and increased muscle activation of the arm and shoulder muscles during major parts of the cranking cycle.

The origins of evil: From lesions to the functional architecture of the antisocial brain

In the past decades, a growing body of evidence has suggested that some individuals may exhibit antisocial behaviors following brain lesions. Recently, some authors have shown that lesions underpinning antisocial behaviors may disrupt a particular brain network during resting-state. However, it remains unknown whether these brain lesions may alter specific mental processes during tasks. Therefore, we conducted meta-analytic co-activation analyses on lesion masks of 17 individuals who acquired antisocial behaviors following their brain lesions. Each lesion mask was used as a seed of interest to examine their aberrant co-activation network using a database of 143 whole-brain neuroimaging studies on antisocial behaviors (n = 5,913 subjects). We aimed to map the lesion brain network that shows deficient activity in antisocial population against a null distribution derived from 655 control lesions. We further characterized the lesion-based meta-analytic network using term-based decoding (Neurosynth) as well as receptor/transporter density maps (JuSpace). We found that the lesion meta-analytic network included the amygdala, orbitofrontal cortex, ventro- and dorso-medial prefrontal cortex, fusiform face area, and supplementary motor area (SMA), which correlated mainly with emotional face processing and serotoninergic system (5-HT_1A and 5-HTT). We also investigated the heterogeneity in co-activation networks through data-driven methods and found that lesions could be grouped in four main networks, encompassing emotional face processing, general emotion processing, and reward processing. Our study shows that the heterogeneous brain lesions underpinning antisocial behaviors may disrupt specific mental processes, which further increases the risk for distinct antisocial symptoms. It also highlights the importance and complexity of studying brain lesions in relationship with antisocial behaviors.

Quantifying Coordination between Agonist and Antagonist Elbow Muscles during Backhand Crosscourt Shots in Adult Female Squash Players

The purpose of this study was to quantify the coordination between agonist and antagonist elbow muscles during squash backhand crosscourt shots in adult female players. Ten right-handed, international-level, female squash players participated in the study. The electrical muscle activity of two right elbow agonist/antagonist muscles, the biceps brachii and triceps brachii, were recorded using a surface EMG system, and processed using the integrated EMG to calculate a co-activation index (CoI) for the preparation phase, the execution phase, and the follow-through phase. A significant effect of the phases on the CoI was observed. Co-activation was significantly different between the follow-through and the execution phase (45.93 ± 6.00% and 30.14 ± 4.11%, p < 0.001), and also between the preparation and the execution phase (44.74 ± 9.88% and 30.14 ± 4.11%, p < 0.01). No significant difference was found between the preparation and the follow-through phase (p = 0.953). In conclusion, the co-activation of the elbow muscles varies within the squash backhand crosscourt shots. The highest level of co-activation was observed in the preparation phase and the lowest level of co-activation was observed during the execution. The co-activation index could be a useful method for the interpretation of elbow muscle co-activity during a squash backhand crosscourt shot.

Influence of jump-landing direction on dynamic postural stability and hamstring-to-quadriceps co-activation ratio

This study investigated the effect of jump landing direction and leg dominance on the Dynamic Postural Stability Index (DPSI) and the importance of the hamstring-to-quadriceps (H/Q) co-activation ratio. Fifteen female sports players performed unilateral jump landing, for the dominant (DL) and the non-dominant (NDL) legs in anterior (AJL), lateral (LJL), and vertical directions (DJL). The results indicated that the DPSI was higher in DJL compared to LJL and AJL. Besides, the DPSI score during DJL was higher in NDL indicating lower stabilization capacity associated with a lower H/Q co-activation ratio. A significant correlation was found between H/Q co-activation ratio and DPSI in the DL during AJL (r = -0.57). Current results suggest that DJL was more appropriate to evaluate dynamic postural stability since it highlights limb asymmetry. In addition, H/Q co-activation appears to play an essential role in the effectiveness of ground reaction force stabilization during jump landing.

Effects of Power and Ballistic Training on Table Tennis Players' Electromyography Changes

The aim of the present study was to analyze the effects of ballistic and power training on table tennis players' electromyography (EMG) changes. Thirty male table tennis players, who were able to perform top spin strikes properly, were randomly assigned to three groups: power training (PT; n = 10); ballistic training (BT; n = 10); and no training (CON = control group; n = 10). PT and BT were performed 3 times weekly for 8 weeks. Before and after training programs, a one-repetition maximum test (1RM) and the EMG activity of all the subjects' upper/lower body muscles while performing top spin strokes were analyzed. After training, significant interactions (group × time) were observed in increasing 1RM strength in upper/lower muscles (p < 0.05). However, neither training type had any significant effect on muscle EMG activity. These findings suggest that there should not necessarily be any significant change in the EMG signal after BT and PT despite the increase in muscle strength.

Production and Perception of Intentional and Unintentional Actions

Physical approach to biological movement is based on the idea of control with referent spatial coordinates for effectors, from the whole body to single muscles. Within this framework, neural control signals induce changes in parameters of corresponding biology-specific laws of nature, and motor performance emerges as a result of interaction with the external force field. This approach is naturally compatible with the principle of abundance and the uncontrolled manifold hypothesis, which offer the framework for analysis of movement stability. The presence of two basic commands, reciprocal and co-activation, makes even single-effector tasks abundant and allows stabilizing their performance at the control level. Kinesthetic perception can be viewed as the process of estimating afferent signals within a reference system provided by the efferent process. Percepts are reflections of stable iso-perceptual manifolds in the combined afferent-efferent multi-dimensional space. This approach offers new, logical and based on laws of nature, interpretations for such phenomena as muscle co-activation, unintentional drifts in performance, and vibration-induced kinesthetic illusions. It also allows predicting new phenomena such as counter-intuitive effects of muscle co-activation of force production and perception, vibration-induced force illusions, performance drifts at two different speeds, and high variability in matching the contribution of individual elements in multi-element tasks. This approach can be developed for various subfields of movement studies including studies of athletics, movement disorders, and movement rehabilitation.

Factors modulating cross-linguistic co-activation in bilinguals

Activation of both of a bilingual's languages during auditory word recognition has been widely documented. Here, we argue that if parallel activation in bilinguals is the result of a bottom-up process where phonetic features that overlap across two languages activate both linguistic systems, then the robustness of such parallel activation is in fact surprising. This is because phonemes across two different languages are rarely perfectly matched to each other in phonetic features. For instance, across Spanish and English, a "voiced" stop is realized in phonetically-distinct ways, and therefore, words that begin with voiced stops in English do not in fact fully overlap in phonetic features with words in Spanish. In two eye-tracking experiments using a visual world paradigm, we examined the effect of a phonemic match (English /b/ matched to Spanish /b/) vs. a phonetic match (English /b/ matched to Spanish /p/) on cross-linguistic co-activation (English words co-activating Spanish) in Spanish L1 and in Spanish L2 speakers. We found that while phonemic matching induced co-activation in both Spanish L1 and Spanish L2 speakers, phonetic matching did not. Together, these results indicate that co-activation of two languages in bilinguals may proceed through activation of categorical phonemic information rather than through activation of phonetic features.

Refinement and Reactivation of a Taste-Responsive Hippocampal Network

Animals need to remember the locations of nourishing and toxic food sources for survival, a fact that necessitates a mechanism for associating taste experiences with particular places. We have previously identified such responses within hippocampal place cells [1], the activity of which is thought to aid memory-guided behavior by forming a mental map of an animal's environment that can be reshaped through experience [2-7]. It remains unknown, however, whether taste responsiveness is intrinsic to a subset of place cells or emerges as a result of experience that reorganizes spatial maps. Here, we recorded from neurons in the dorsal CA1 region of rats running for palatable tastes delivered via intra-oral cannulae at specific locations on a linear track. We identified a subset of taste-responsive cells that, even prior to taste exposure, had larger place fields than non-taste-responsive cells overlapping with stimulus delivery zones. Taste-responsive cells' place fields then contracted as a result of taste experience, leading to a stronger representation of stimulus delivery zones on the track. Taste-responsive units exhibited increased sharp-wave ripple co-activation during the taste delivery session and subsequent rest periods, which correlated with the degree of place field contraction. Our results reveal that novel taste experience evokes responses within a preconfigured network of taste-responsive hippocampal place cells with large fields, whose spatial representations are refined by sensory experience to signal areas of behavioral salience. This represents a possible mechanism by which animals identify and remember locations where ecologically relevant stimuli are found within their environment.

Somatosensory Function Influences Aberrant Gait Biomechanics Following Anterior Cruciate Ligament Reconstruction

Osteoarthritis is common following anterior cruciate ligament reconstruction (ALCR), and aberrant gait biomechanics are considered a primary contributor. Somatosensory dysfunction potentially alters gait biomechanics, but this association is unclear. Therefore, the purposes of this investigation were to compare somatosensory function between limbs and evaluate associations between somatosensory function and gait biomechanics linked to osteoarthritis development in individuals with ALCR. Seventy-three volunteers with ALCR participated. Gait biomechanics (peak vertical ground reaction force magnitude and loading rate, peak internal knee extension and valgus moments, peak knee flexion and varus angles, and quadriceps/hamstrings co-activation) were assessed as subjects walked at their preferred speed. The somatosensory function was assessed via joint position sense error (knee flexion) and vibratory perception threshold (femoral epicondyles, malleoli, and first metatarsal). Though somatosensory function did not differ between the ACLR and contralateral limbs, poorer joint position sense in the ACLR limb was associated with lower loading rates and internal knee extension moments, and greater co-activation. Poorer vibratory perception at the medial and lateral malleoli and first metatarsal head in the ACLR limb was associated with lower loading rates, greater internal knee valgus moments and varus angles, and greater co-activation. Poorer vibratory perception at the medial malleolus and first metatarsal head in the contralateral limb was associated with greater peak knee varus angles and internal knee valgus moments. These results suggest that future research evaluating rehabilitation approaches for improving somatosensory function is warranted as a potential approach for restoring normal gait biomechanics and reducing osteoarthritis risk. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:620-628, 2020.

Cortical and affective regulation of autonomic coordination

Although anatomical research clearly demonstrates the ability of the sympathetic and parasympathetic branches of the autonomic nervous system to independently influence cardiac function, little research has examined whether coordinated activation is typical or whether the extent of autonomic coordination is situationally dependent. This study examines the extent of coordination between sympathetic (cardiac pre-ejection period: PEP) and parasympathetic (respiratory sinus arrhythmia: RSA) influences on the cardiac function to determine whether coordination is a trait-like between-person characteristic or a state-varying within-person phenomenon, and if so, whether variability in autonomic coordination is modulated by cognitive (P3b amplitude) or affective state. Kindergarten-aged children (n = 257) completed a go/no-go task administered in blocks designed to induce affective states through the delivery of reward (Blocks 1 and 3) and frustration (Block 2). Results from multilevel models that allowed for the simultaneous examination of between-person and within-person associations in the repeated measures data suggested that (a) children with higher overall RSA also tended to have higher overall PEP; (b) at within-person level, RSA and PEP tended to be reciprocally coordinated; but that (c) when frustration invokes cognitive disengagement, coordination between parasympathetic and sympathetic systems demonstrate compensatory coordination. These findings highlight the extent to which the coordination of autonomic systems is a dynamic state-like phenomenon rather than a trait-like individual differences characteristic.

Biomechanics of Vertical Posture and Control with Referent Joint Configurations

Our study compared the results of two methods of analysis of postural sway during human quiet standing, the rambling-trembling (Rm-Tr) decomposition and the analysis of the point of intersection of the ground reaction forces (zIP analysis). Young, healthy subjects were required to stand naturally and with an increased level of leg/trunk muscle co-activation under visual feedback on the magnitude of a combined index of muscle activation (muscle mode). The main findings included the shift of zIP toward higher frequencies and strong correlations between Tr and zIP when the subjects stood with increased muscle co-activation. We interpret the results within the idea of whole-body control with a set of primitives associated with referent coordinates in the joint configuration space.

Analysis of Muscle Load-Sharing in Patients With Lateral Epicondylitis During Endurance Isokinetic Contractions Using Non-linear Prediction

The aim of this paper is to analyze muscle load-sharing in patients with Lateral Epicondylitis during dynamic endurance contractions by means of non-linear prediction of surface EMG signals. The proposed non-linear cross-prediction scheme was used to predict the envelope of an EMG signal and is based on locally linear models built in a lag-embedded Euclidean space. The results were compared with a co-activation index, a common measure based on the activation of a muscle pair. Non-linear prediction revealed changes in muscle coupling, that is load-sharing, over time both in a control group and Lateral Epicondylitis (p < 0.05), even when subjects did not report pain at the end of the exercise. These changes were more pronounced in patients, especially in the first part of the exercise and up to 50% of the total endurance time (p < 0.05). By contrast, the co-activation index showed no differences between groups. Results reflect the changing nature of muscular activation strategy, presumably because of the mechanisms triggered by fatigue. Strategies differ between controls and patients, pointing to an altered coordination in Lateral Epicondylitis.

Co-activation of Taxonomic and Thematic Relations in Spoken Word Comprehension: Evidence From Eye Movements

Evidence from behavior, computational linguistics, and neuroscience studies supported that semantic knowledge is represented in (at least) two semantic systems (i.e., taxonomic and thematic systems). It remains unclear whether, and to what extent taxonomic and thematic relations are co-activated. The present study investigated the co-activation of the two types of semantic representations when both types of semantic relations are simultaneously presented. In a visual-world task, participants listened to a spoken target word and looked at a visual display consisted of a taxonomic competitor, a thematic competitor and two distractors. Growth curve analyses revealed that both taxonomic and thematic competitors attracted visual attention during the processing of the target word but taxonomic competitor received more looks than thematic competitor. Moreover, although fixations on taxonomic competitor rose faster than thematic competitor, these two types of competitors started to attract more fixations than distractor in a similar time window. These findings indicate that taxonomic and thematic relations are co-activated by the spoken word, the activation of taxonomic relation is stronger and rise faster than thematic relation.

Co-activation of SAM and HPA responses to acute stress: A review of the literature and test of differential associations with preadolescents' internalizing and externalizing

Understanding co-activation patterns of the hypothalamic-pituitary-adrenal axis (HPA) and sympathetic adrenal medullary (SAM) during early adolescence may illuminate risk for development of internalizing and externalizing problems. The present study advances empirical work on the topic by examining SAM-HPA co-activation during both the reactivity and recovery phases of the stress response following acute stress exposure. Fourth and fifth grade boys and girls (N = 149) provided cortisol and alpha-amylase via saliva at seven times throughout a 95-min assessment in which they were administered the modified Trier Social Stress Test. Parents reported on adolescents' life stress, pubertal development, medication use, and externalizing problems. Adolescents reported their own internalizing symptoms. Multiple linear regressions tested both direct and interactive effects of SAM and HPA reactivity and recovery on internalizing and externalizing problems. Results from these analyses showed that whereas SAM and HPA reactivity interacted to predict internalizing symptoms, it was their interaction during the recovery phase that predicted externalizing. Concurrent high SAM and HPA reactivity scores predicted high levels of internalizing and concurrently low SAM and HPA recovery scores predicted high levels of externalizing. Implications of the findings for further study and clinical application are discussed.

Myoelectric Computer Interface Training for Reducing Co-Activation and Enhancing Arm Movement in Chronic Stroke Survivors: A Randomized Trial

BACKGROUND

Abnormal muscle co-activation contributes to impairment after stroke. We developed a myoelectric computer interface (MyoCI) training paradigm to reduce abnormal co-activation. MyoCI provides intuitive feedback about muscle activation patterns, enabling decoupling of these muscles.

OBJECTIVE

To investigate tolerability and effects of MyoCI training of 3 muscle pairs on arm motor recovery after stroke, including effects of training dose and isometric versus movement-based training.

METHODS

We randomized chronic stroke survivors with moderate-to-severe arm impairment to 3 groups. Two groups tested different doses of isometric MyoCI (60 vs 90 minutes), and one group tested MyoCI without arm restraint (90 minutes), over 6 weeks. Primary outcome was arm impairment (Fugl-Meyer Assessment). Secondary outcomes included function, spasticity, and elbow range-of-motion at weeks 6 and 10.

RESULTS

Over all 32 subjects, MyoCI training of 3 muscle pairs significantly reduced impairment (Fugl-Meyer Assessment) by 3.3 ± 0.6 and 3.1 ± 0.7 ( P < 10^-4) at weeks 6 and 10, respectively. Each group improved significantly from baseline; no significant differences were seen between groups. Participants' lab-based and home-based function also improved at weeks 6 and 10 ( P ≤ .01). Spasticity also decreased over all subjects, and elbow range-of-motion improved. Both moderately and severely impaired patients showed significant improvement. No participants had training-related adverse events. MyoCI reduced abnormal co-activation, which appeared to transfer to reaching in the movement group.

CONCLUSIONS

MyoCI is a well-tolerated, novel rehabilitation tool that enables stroke survivors to reduce abnormal co-activation. It may reduce impairment and spasticity and improve arm function, even in severely impaired patients.

FAM3B (PANDER) functions as a co-activator of FOXO1 to promote gluconeogenesis in hepatocytes

FAM3B, also known as PANcreatic DERived factor (PANDER), promotes gluconeogenesis and lipogenesis in hepatocytes. However, the underlying mechanism(s) still remains largely unclear. This study determined the mechanism of PANDER-induced FOXO1 activation in hepatocytes. In mouse livers and cultured hepatocytes, PANDER protein is located in both the cytoplasm and nucleus. Nuclear PANDER distribution was increased in the livers of obese mice. In cultured mouse and human hepatocytes, PANDER was co-localized with FOXO1 in the nucleus. PANDER directly interacted with FOXO1 in mouse and human hepatocytes. PANDER overexpression enhanced PANDER-FOXO1 interaction, and detained FOXO1 in the nucleus upon insulin stimulation in hepatocytes. With the increase in PANDER-FOXO1 interaction, PANDER overexpression upregulated the expression of gluconeogenic genes and promoted gluconeogenesis in both human and mouse hepatocytes. Luciferase reporter assays further revealed that PANDER augmented the transcriptional activity of FOXO1 on gluconeogenic genes. Moreover, PANDER overexpression also interfered the binding of AS1842856, a specific FOXO1 inhibitor, with FOXO1, and impaired its inhibitory effects on gluconeogenic gene expression and gluconeogenesis in hepatocytes. siRNA mediated-silencing of FOXO1 inhibited PANDER-promoted gluconeogenic gene expression and glucose production in hepatocytes. In conclusion, PANDER protein is abundantly present in the nucleus, where it functions as a new co-activator of FOXO1 to induce gluconeogenic gene expression in hepatocytes.

Development of a lumbar EMG-based coactivation index for the assessment of complex dynamic tasks

The objective of this study was to develop and test an EMG-based coactivation index and compare it to a coactivation index defined by a biologically assisted lumbar spine model to differentiate between tasks. The purpose was to provide a universal approach to assess coactivation of a multi-muscle system when a computational model is not accessible. The EMG-based index developed utilised anthropometric-defined muscle characteristics driven by torso kinematics and EMG. Muscles were classified as agonists/antagonists based upon 'simulated' moments of the muscles relative to the total 'simulated' moment. Different tasks were used to test the range of the index including lifting, pushing and Valsalva. Results showed that the EMG-based index was comparable to the index defined by a biologically assisted model (r² = 0.78). Overall, the EMG-based index provides a universal, usable method to assess the neuromuscular effort associated with coactivation for complex dynamic tasks when the benefit of a biomechanical model is not available. Practitioner Summary: A universal coactivation index for the lumbar spine was developed to assess complex dynamic tasks. This method was validated relative to a model-based index for use when a high-end computational model is not available. Its simplicity allows for fewer inputs and usability for assessment of task ergonomics and rehabilitation.

Mesopore- and Macropore-Dominant Nitrogen-Doped Hierarchically Porous Carbons for High-Energy and Ultrafast Supercapacitors in Non-Aqueous Electrolytes

Non-aqueous electrolytes (e.g., organic and ionic liquid electrolytes) can undergo high working voltage to improve the energy densities of supercapacitors. However, the large ion sizes, high viscosities, and low ionic conductivities of organic and ionic liquid electrolytes tend to cause the low specific capacitances, poor rate, and cycling performance of supercapacitors based on conventional micropore-dominant activated carbon electrodes, limiting their practical applications. Herein, we propose an effective strategy to simultaneously obtain high power and energy densities in non-aqueous electrolytes via using a cattle bone-derived porous carbon as an electrode material. Because of the unique co-activation of KOH and hydroxyapatite (HA) within the cattle bone, nitrogen-doped hierarchically porous carbon (referred to as NHPC-HA/KOH) is obtained and possesses a mesopore- and macropore-dominant porosity with an ultrahigh specific surface area (2203 m² g^-1) of meso- and macropores. The NHPC-HA/KOH electrodes exhibit superior performance with specific capacitances of 224 and 240 F g^-1 at 5 A g^-1 in 1.0 M TEABF₄/AN and neat EMIMBF₄ electrolyte, respectively. The symmetric supercapacitor using NHPC-HA/KOH electrodes can deliver integrated high energy and power properties (48.6 W h kg^-1 at 3.13 kW kg^-1 in 1.0 M TEABF₄/AN and 75 W h kg^-1 at 3.75 kW kg^-1 in neat EMIMBF₄), as well as superior cycling performance (over 89% of the initial capacitance after 10 000 cycles at 10 A g^-1).

Knee extensor fatigue developed during high-intensity exercise limits lower-limb power production

We investigated the association between changes in vastii electromyography (EMG) and knee extensor fatigue during high-intensity cycling, and the subsequent effect on lower-limb power and intermuscular coordination during all-out cycling. On two separate days, participants completed 30-s all-out cycling or 10-min of high-intensity cycling followed by 30-s all-out cycling. EMG for gluteus maximus (GMAX), rectus femoris (RF), vastii (VAS), hamstrings (HAM) and gastrocnemius (GAS); co-activation for GMAX/RF, VAS/HAM and VAS/GAS; isometric maximal voluntary force (IMVF) and resting twitch (RT) of the knee extensors were measured. VAS EMG increases during high-intensity cycling (6% to 14%, P < 0.05) were negatively correlated (r = -0.791, P < 0.05) with knee extensor IMVF decreases (-2% to-36%, P < 0.05) following the exercise. Knee extensor IMVF decreases were positively correlated (r = 0.757, P < 0.05) with all-out cycling power reductions (0% to -27%, P < 0.05). VAS/GAS co-activation did not change (P > 0.05) during all-out cycling while VAS and GAS EMG decreased. Larger increase in VAS EMG during high-intensity cycling was associated with greater knee extensor fatigue and larger power reduction during all-out cycling. High VAS/GAS co-activation potentially limited power reduction induced by knee extensor fatigue during all-out cycling.

Synergistic Co-activation Increases the Extent of Mechanical Interaction between Rat Ankle Plantar-Flexors

Force transmission between rat ankle plantar-flexors has been found for physiological muscle lengths and relative positions, but only with all muscles maximally activated. The aims of this study were to assess intermuscular mechanical interactions between ankle plantar-flexors during (i) fully passive conditions, (ii) excitation of soleus (SO), (iii) excitation of lateral gastrocnemius (LG), and (iv) during co-activation of SO, and LG (SO&LG). We assessed effects of proximal lengthening of LG and plantaris (PL) muscles (i.e., simulating knee extension) on forces exerted at the distal SO tendon (F_SO) and on the force difference between the proximal and distal LG+PL tendons (ΔF_LG+PL) of the rat. LG+PL lengthening increased F_SO to a larger extent (p = 0.017) during LG excitation (0.0026 N/mm) than during fully passive conditions (0.0009 N/mm). Changes in F_SO in response to LG+PL lengthening were lower (p = 0.002) during SO only excitation (0.0056 N/mm) than during SO&LG excitation (0.0101 N/mm). LG+PL lengthening changed ΔF_LG+PL to a larger extent (p = 0.007) during SO excitation (0.0211 N/mm) than during fully passive conditions (0.0157 N/mm). In contrast, changes in ΔF_LG+PL in response to LG+PL lengthening during LG excitation (0.0331 N/mm) were similar (p = 0.161) to that during SO&LG excitation (0.0370 N/mm). In all conditions, changes of F_SO were lower than those of ΔF_LG+PL. This indicates that muscle forces were transmitted not only between LG+PL and SO, but also between LG+PL and other surrounding structures. In addition, epimuscular myofascial force transmission between rat ankle plantar-flexors was enhanced by muscle activation. However, the magnitude of this interaction was limited.

Trunk muscle activation characteristics in patients with severe haemophilia

INTRODUCTION

Recurrent bleeding episodes in patients with haemophilia (PWH) lead to joint alterations and therewith disturbed muscle coordination patterns. Major weight-bearing joints are affected most. However, possible effects on trunk muscle activity have not been examined so far. The objective of this work was to study consequences of haemarthropathy on characteristics of trunk muscles in PWH while standing on surfaces with different mechanical properties.

METHODS

Surface EMG of internal oblique (IO) and multifidus (MF) muscles were bilaterally recorded during a natural bilateral stance in 20 PWH with severe haemophilia A [age: 42 years (SD: 10)] and 25 non-haemophilic controls [NHC, 43 (12)]. Amplitude ratios, a symmetry index between sides and the co-activation ratio of IO over MF served as outcome measures and compared standing on three different surfaces (stable, soft, unsteady).

RESULTS

PWH revealed markedly restricted lower extremity joints (P < 0.001), but without any hint of back pain. Neither result revealed significant main or interaction effects of 'group' (P > 0.24). Group-independent analyses showed amplitude ratios (MF: P < 0.05) as well as symmetry indices (MF: P < 0.02) significantly altered by 'surface' in NHC only. Effects of utilizing soft vs. unsteady surfaces were not detectable (P > 0.77).

CONCLUSION

Utilizing unstable surfaces does not lead to altered trunk muscle activity in PWH. Differently than expected, a quite similar behaviour of lower trunk muscles in terms of applied indices can be found in PWH and NHC. Ascending alterations of muscle coordination in PWH could not be verified.

Transfer of tactile perceptual learning to untrained neighboring fingers reflects natural use relationships

Tactile learning transfers from trained to untrained fingers in a pattern that reflects overlap between the representations of fingers in the somatosensory system (e.g., neurons with multifinger receptive fields). While physical proximity on the body is known to determine the topography of somatosensory representations, tactile coactivation is also an established organizing principle of somatosensory topography. In this study we investigated whether tactile coactivation, induced by habitual inter-finger cooperative use (use pattern), shapes inter-finger overlap. To this end, we used psychophysics to compare the transfer of tactile learning from the middle finger to its adjacent fingers. This allowed us to compare transfer to two fingers that are both physically and cortically adjacent to the middle finger but have differing use patterns. Specifically, the middle finger is used more frequently with the ring than with the index finger. We predicted this should lead to greater representational overlap between the former than the latter pair. Furthermore, this difference in overlap should be reflected in differential learning transfer from the middle to index vs. ring fingers. Subsequently, we predicted temporary learning-related changes in the middle finger's representation (e.g., cortical magnification) would cause transient interference in perceptual thresholds of the ring, but not the index, finger. Supporting this, longitudinal analysis revealed a divergence where learning transfer was fast to the index finger but relatively delayed to the ring finger. Our results support the theory that tactile coactivation patterns between digits affect their topographic relationships. Our findings emphasize how action shapes perception and somatosensory organization.

Age-specific neuromuscular interaction during elderly habitual running

AIM

It has been reported that advancing age causes tendons to become more compliant and fascicles length shorter. This could then lead to enhancement of movement efficiency provided that the elderly adults can activate their muscles in the same way as the younger adults (YOUNG) during dynamic movements. This study was designed to examine the age-specific behaviour of the medial gastrocnemius (MG) fascicles and tendinous tissues together with lower-leg muscle activities when the well-trained elderly runners ran on the treadmill at preferred speeds.

METHODS

The well-trained 11 elderly subjects (ELD) who have running experiences and 11 YOUNG were recruited as subjects. While ELD were running on the treadmill at their preferred speed, the lengths of the MG fascicles and tendinous tissues (Lfa and LTT respectively) were measured by ultrasonography together with kinematics and lower-leg muscle activities.

RESULTS

Although the behaviour of the MG muscle-tendon unit did not show any significant differences between both groups during the contact, our results showed significant differences in fascicle-tendinous tissue behaviour as well as muscle activities. The LTT during the entire contact phase was greater in ELD than in YOUNG (P < 0.001). Co-activation of lower-leg muscles from pre-activation to braking phases was higher in ELD than in YOUNG (P < 0.01). The changes of the Lfa during contact were less, and the LTT shortening was greater in ELD than in YOUNG (P < 0.001).

CONCLUSION

These results imply that ELD cannot activate their muscles similar to YOUNG during running, and those different activities may modify the Lfa to utilize the tendon elasticity effectively.

A kinematic and metabolic analysis of the first Lu of Tai Chi in experts and beginners

The aim of this study was to compare movement kinematics, cocontraction times, and metabolic data in expert and nonexpert Tai Chi practitioners. Significant differences were observed for all kinematic parameters: experts moved smoothly (lower jerk) and with a lower frequency. No differences in metabolic and electromyography data were observed but for the breathing pattern (experts breathed slowly and deeply). Movement frequency and breathing pattern are thus the main features that distinguish expert and nonexpert practitioners.

Modeling violations of the race model inequality in bimodal paradigms: co-activation from decision and non-decision components

The redundant-signals paradigm (RSP) is designed to investigate response behavior in perceptual tasks in which response-relevant targets are defined by either one or two features, or modalities. The common finding is that responses are speeded for redundantly compared to singly defined targets. This redundant-signals effect (RSE) can be accounted for by race models if the response times do not violate the race model inequality (RMI). When there are violations of the RMI, race models are effectively excluded as a viable account of the RSE. The common alternative is provided by co-activation accounts, which assume that redundant target signals are integrated at some processing stage. However, "co-activation" has mostly been only indirectly inferred and the accounts have only rarely been explicitly modeled; if they were modeled, the RSE has typically been assumed to have a decisional locus. Yet, there are also indications in the literature that the RSE might originate, at least in part, at a non-decisional or motor stage. In the present study, using a distribution analysis of sequential-sampling models (ex-Wald and Ratcliff Diffusion model), the locus of the RSE was investigated for two bimodal (audio-visual) detection tasks that strongly violated the RMI, indicative of substantial co-activation. Three model variants assuming different loci of the RSE were fitted to the quantile reaction time proportions: a decision, a non-decision, and a combined variant both to vincentized group as well as individual data. The results suggest that for the two bimodal detection tasks, co-activation has a shared decisional and non-decisional locus. These findings point to the possibility that the mechanisms underlying the RSE depend on the specifics (task, stimulus, conditions, etc.) of the experimental paradigm.

Behavioral responses to social separation stressor change across development and are dynamically related to HPA activity in marmosets

Psychosocial stressors activate two distinct stress-response systems, a central, behavioral response, and a peripheral, endocrine response. Both behavioral and endocrine responses to stressors are subject to individual and developmental variables, but it is not known whether stressor induced behaviors are stable across development, and how they correspond with changes in the endocrine component of the stress response. We characterized the development and stability of behavioral responses to a mild psychosocial stressor in marmosets (Callithrix geoffroyi), and assessed the degree to which the behavioral and endocrine stress-response systems were co-activated. The behavioral response to stressors was stable within individuals, but only some stressor-induced behaviors changed as the monkeys developed. Overall, there was more variability in the development of behavioral responses compared to stress-induced endocrine profiles found previously [French et al., 2012. Horm Behav 61:196-203]. In young marmosets, only increased alarm calling was correlated with increased cortisol reactivity, and in older marmosets increased cage manipulations and motor activity were associated with poorer post-stressor cortisol regulation. Because these relationships were so few, we conclude that while the behavioral and endocrine systems follow a similar developmental trajectory, each system maintains a level of independence. Furthermore, the relationship between stressor-induced behaviors and HPA activity changes across development.

A model of the basal ganglia in voluntary movement and postural reactions

A basal ganglia central pattern generator (CPG) is developed and its role in voluntary movements on the ground and postural reactions on a disturbed platform are studied and analysed by simulation. Biped dynamics and platform kinematics are utilised. The effects of agonist-antagonist muscular co-activation and joint stiffness are formulated. The implementation of the necessary counter-manoeuvres for maintaining balance and postural stability is studied. A control strategy, applicable to large systems, is formulated. The biped manoeuvres and transitions terminate in pre-specified intervals of time. Gravity is included and compensated for. Certain voluntary and postural adjustment strategies are the same but are initiated differently. Further experimental/computational research may identify the central nervous system and sensory paths that lead to the CPG. All actuator forces linearly evolve in time from their original values to their terminal values. There are no central continuous feedback loops present. Monitoring and sensing, however, are ongoing. The counter-manoeuvres are based on learned human-like voluntary movements that are triggered by the disturbance. The required central inputs to the musculoskeletal system are designed in the CPG. A functional structure for the CPG is proposed. The effect of certain disorders and malfunctions of the CPG are studied by simulation.

Autonomic activity and somatic symptoms in response to success vs. failure on a cognitive task: a comparison of chronic abdominal pain patients and well children

OBJECTIVES

To compare autonomic nervous system (ANS) activity and somatic symptoms in chronic abdominal pain (CAP) patients and well children during (a) resting baseline, (b) training in a cognitive task, and (c) random assignment to success vs. failure on the task.

METHODS

The ECG was continuously recorded with a dual lead system (Biopac) in 45 CAP patients and 22 well children, ages 9-16 years (mean age=12.3). Heart rate variability (HRV) was analyzed during the 5-min resting baseline, training, and success/failure on the task. Performance expectations were assessed before the task. Gastrointestinal (GI) and non-GI somatic symptoms were assessed before and after the task.

RESULTS

Compared to well children, CAP patients reported lower expectations for their task performance and higher GI symptoms (P's<.05). During success, CAP patients exhibited significant increases in both sympathetic (P<.05) and parasympathetic (P<.05) activity, whereas well children exhibited no change in ANS activity. During failure, CAP patients exhibited significant increases in somatic symptoms (<.05) but no change in ANS activity.

CONCLUSIONS

The lower performance expectations of CAP patients compared to well children may have influenced their experience of success and contributed to differences in their autonomic activity.