Movement Onset Research Articles

Effects of task difficulty on performance and event-related bradycardia during preparation for action

The slowing of heart rate prior to movement onset has been presented as a marker of task-related cognitive processing and linked with performance accuracy. Here we examined this event-related bradycardia and task performance as a function of task difficulty. Forty experienced golfers completed a series of golf putting conditions that manipulated task difficulty by varying target distance, target size, and surface contour. Performance was measured by the number of holed putts and finishing distance from the hole. Physiological activity was recorded throughout. Analyses confirmed that performance varied as a function of task difficulty, worsening with longer distances to target, smaller targets, and sloping paths to target. Task difficulty also impacted the cardiac response, including the rate of heart rate deceleration, change in heart rate, and heart rate at impact. These heart rate metrics were found to correlate with performance strongly, moderately, and weakly, respectively. In conclusion, heart rate deceleration in the moments preceding movement onset was affected by task difficulty. Features of this cardiac deceleration pattern were characteristic of successful performance. Our findings are discussed in terms of the role of cognitive and motor processes during the execution of complex motor skills.

Pre-movement event-related potentials and multivariate pattern of EEG encode action outcome prediction.

Self-initiated movements are accompanied by an efference copy, a motor command sent from motor regions to the sensory cortices, containing a prediction of the movement's sensory outcome. Previous studies have proposed pre-motor event-related potentials (ERPs), including the readiness potential (RP) and its lateralized sub-component (LRP), as potential neural markers of action feedback prediction. However, it is not known how specific these neural markers are for voluntary (active) movements as compared to involuntary (passive) movements, which produce much of the same sensory feedback (tactile, proprioceptive) but are not accompanied by an efference copy. The goal of the current study was to investigate how active and passive movements are distinguishable from premotor electroencephalography (EEG), and to examine if this change of neural activity differs when participants engage in tasks that differ in their expectation of sensory outcomes. Participants made active (self-initiated) or passive (finger moved by device) finger movements that led to either visual or auditory stimuli (100 ms delay), or to no immediate contingency effects (control). We investigated the time window before the movement onset by measuring pre-movement ERPs time-locked to the button press. For RP, we observed an interaction between task and movement. This was driven by movement differences in the visual and auditory but not the control conditions. LRP conversely only showed a main effect of movement. We then used multivariate pattern analysis to decode movements (active vs. passive). The results revealed ramping decoding for all tasks from around -800 ms onwards up to an accuracy of approximately 85% at the movement. Importantly, similar to RP, we observed lower decoding accuracies for the control condition than the visual and auditory conditions, but only shortly (from -200 ms) before the button press. We also decoded visual vs. auditory conditions. Here, task is decodable for both active and passive conditions, but the active condition showed increased decoding shortly before the button press. Taken together, our results provide robust evidence that pre-movement EEG activity may represent action-feedback prediction in which information about the subsequent sensory outcome is encoded.

Stroboscopic Eyewear Applied During Warm-Up Does Not Provide Additional Benefits to the Sport-Specific Reaction Speed in Highly Trained Table Tennis Athletes.

While long-term training with stroboscopic eyewear suggests performance-enhancing effects on visuomotor abilities, it remains unclear whether a short-term application, for example, during a warm-up, results in immediate performance gains. This study evaluated potential performance-enhancing effects of stroboscopic eyewear applied during warm-up on reaction speed that may provide athletes an edge in visuomotor-demanding sports. Twenty-eight international-level table tennis athletes participated in this study. Participants performed their individual 10-minute table-tennis-specific warm-up under normal visual conditions and with stroboscopic eyewear. Prior to and after the warm-up, visuomotor reaction time was assessed in a sport-specific reaction test where athletes had to return 30 table tennis balls played by a ball machine at high speed to their backhand side. Reaction time was determined as the interval between ball output and movement onset as triggered by a mechanical switch. Furthermore, the time between ball-table contact and ball-racket contact (hit time) was analyzed as an indicator of how early the athletes intercepted the ball. Reaction time significantly improved following the warm-up (P < .001, ηp2=.393). However, there was no additional benefit of the stroboscopic eyewear (P = .338, ηp2=.034). No changes after the warm-up were observed for hit time (P = .246, ηp2=.055). The results indicate that warm-up facilitated visuomotor reaction speed; however, stroboscopic eyewear did not provide additional positive effects when compared to a warm-up under normal visual conditions. While shutter glasses may be useful for training over longer periods, short-term positive effects were not supported in this study.

Decoding Upper-Limb Movement Intention Through Adaptive Dynamic Movement Primitives: A Proof-of-Concept Study with a Shoulder-Elbow Exoskeleton.

This work presents an intention decoding algorithm that can be used to control a 4 degrees-of-freedom shoulder-elbow exoskeleton in reaching tasks. The algorithm was designed to assist the movement of users with upper-limb impairments who can initiate the movement by themselves. It relies on the observation of the initial part of the user's movement through joint angle measures and aims to estimate in real-time the phase of the movement and predict the goal position of the hand in the reaching task. The algorithm is based on adaptive Dynamic Movement Primitives and Gaussian Mixture Models. The performance of the algorithm was verified in robot-assisted planar reaching movements performed by one healthy subject wearing the exoskeleton. Tests included movements of different amplitudes and orientations. Results showed that the algorithm could predict the hand's final position with an error lower than 5 cm after 0.25 s from the movement onset, and that the final position reached during the tests was on average less than 4 cm far from the target position. Finally, the effects of the assistance were observed in a reduction of the activation of the Biceps Brachii and of the time to execute the reaching tasks.

A Bibliometric Analysis of Global Research on Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) are a clinical syndrome characterized by the abrupt onset of major personality, movement, and behavioral changes in a patient with a history of streptococcal infection. We aimed to do a bibliometric analysis of the published research on PANDAS. All the published articles available on the PubMed database from the time of inception till August 2022 were included in the study. All the PubMed IDs (PMID) of the articles were entered in Harvard Catalyst, a free online software, for bibliometric analysis, and data were extracted and verified. A total of 289 relevant published articles were identified. The average number of authors per article was 4.89 and the average number of times an article was cited was 11.19 (excluding self-citation). The H-index of the published articles was 31. The Journal of Child and Adolescent Psychopharmacology published the maximum number of articles ( n = 36). The highest number of average citations (39.50 citations/articles) was for the articles published in the American Journal of Psychiatry. The most common type of articles were journal articles ( n = 259) and of which 27 were original research articles. Most of the original research discusses the effectiveness of various interventions (penicillin and other antibiotic prophylaxis, role of immunoglobulin), neuropsychiatric symptoms, and outcomes in the longitudinal course. Though PANDAS is a well-researched entity, more clinical trials, and large-scale studies will help provide better insight on this subject.

Anion and cation dynamics in a carbon-substituted cesium closo-hydroborate CsCB11H12: 1H and 133Cs NMR studies

Cesium monocarba-hydroborate CsCB11H12 belongs to the family of alkali-metal closo- hydroborate salts which are considered as promising solid electrolytes for battery applications. To study the dynamical properties of this compound at the microscopic level, we have measured the 1H and 133Cs nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates over the temperature range of 80–434 K. Our measurements have revealed a coexistence of two types of reorientational jump processes of the complex [CB11H12]− anions. For the faster of these processes characterized by the average activation energy of 310 meV, the anion reorientations are not “frozen” at the NMR frequency scale down to 120 K. The behavior of the 133Cs NMR line width in CsCB11H12 is consistent with the onset of long-range diffusive motion of Cs+ ions at the frequency scale of ∼104 s−1 above 340 K, and the distinct effects of the diffusive Cs+ jumps on both the 1H and 133Cs spin-lattice relaxation rates become observable above 380 K.

Three-dimensional numerical modeling of ground motion in the Valley of Mexico: A case study from the Mw3.2 earthquake of July 17, 2019

In this study, a 3D physics-based numerical approach, based on the spectral element numerical code SPEED, is used to simulate seismic wave propagation due to a local earthquake in the Mexico City area. The availability of detailed geological, geophysical, geotechnical, and seismological data allowed for the creation of a large-scale (60 km × 60 km in plan, 10 km in depth) heterogeneous 3D numerical model of the Mexico City area, dimensioned to accurately propagate frequencies up to about 1.3 Hz. The results of numerical simulations are validated against the ground motion recordings of the July 17, 2019, Mw3.2 earthquake, with peak ground acceleration exceeding 0.3 g about 1 km away from the epicenter. A good agreement with records is found, quantitatively evaluated through goodness-of-fit checks. Furthermore, for the lake zone, the simulated decay trend of the peak ground velocity with epicentral distance is reasonably close to the observations, for both horizontal and vertical components. In spite of some limitations, the simulations are successful to provide a realistic picture of seismic wave propagation both in the hill and in the lake zones of Mexico City, including the onset of long-duration quasi-monochromatic ground motion in the basin, with strong amplification at low frequencies (between 0.4 and 0.7 Hz). The numerical results also suggest that surface waves, with predominant prograde particle motion at the ground surface and large ellipticities, dominate the wavefield in the lake zone. Based on these positive outcomes, we conclude that this numerical model may be useful for both a better insight into the seismic response of the Valley of Mexico and the simulation of ground motions during larger-magnitude earthquakes, to generate improved seismic damage scenarios in Mexico City.

Synchronization in collectively moving inanimate and living active matter

Whether one considers swarming insects, flocking birds, or bacterial colonies, collective motion arises from the coordination of individuals and entails the adjustment of their respective velocities. In particular, in close confinements, such as those encountered by dense cell populations during development or regeneration, collective migration can only arise coordinately. Yet, how individuals unify their velocities is often not understood. Focusing on a finite number of cells in circular confinements, we identify waves of polymerizing actin that function as a pacemaker governing the speed of individual cells. We show that the onset of collective motion coincides with the synchronization of the wave nucleation frequencies across the population. Employing a simpler and more readily accessible mechanical model system of active spheres, we identify the synchronization of the individuals’ internal oscillators as one of the essential requirements to reach the corresponding collective state. The mechanical ‘toy’ experiment illustrates that the global synchronous state is achieved by nearest neighbor coupling. We suggest by analogy that local coupling and the synchronization of actin waves are essential for the emergent, self-organized motion of cell collectives.

Effects of chronic caffeine on patterns of brain blood flow and behavior throughout the sleep-wake cycle in freely behaving mice.

Caffeine has significant effects on neurovascular activity and behavior throughout the sleep-wake cycle. We used a minimally invasive microchip/video system to continuously record effects of caffeine in the drinking water of freely behaving mice. Chronic caffeine shifted both rest and active phases by up to 2 h relative to the light-dark cycle in a dose-dependent fashion. There was a particular delay in the onset of rapid eye movement (REM) sleep as compared with non-REM sleep during the rest phase. Chronic caffeine increased wakefulness during the active phase and consolidated sleep during the rest phase; overall, there was no net change in the amount of time spent in the wake, sleep, or REM sleep states during caffeine administration. Despite these effects on wakefulness and sleep, chronic caffeine decreased mean cerebral blood volume (CBV) during the active phase and increased mean CBV during the rest phase. Chronic caffeine also increased heart rate variability in both the sleep and wake states. These results provide new insight into the effects of caffeine on the biology of the sleep-wake cycle. Increased blood flow during sleep caused by chronic caffeine may have implications for its potential neuroprotective effects through vascular mechanisms of brain waste clearance.

Transformation of Pluripotency States during Morphogenesis of Mouse and Human Epiblast

The pluripotent status of a cell in vivo is spatio-temporally regulated within embryogenesis and is determined by the processes of self-renewal, endless proliferation and differentiation into all cell types of the body. Previously, the pluripotency was characterized using teratocarcinoma cells. Then this term was applied to the embryonic cells of the preimplantation mouse embryo. Preimplantationally formed mouse and human pluripotent stem cells (PSCs) appear to exist until gastrulation. One of the main events in the early mammalian development is the differentiation of the inner cell mass of the blastocyst (ICM) into a hypoblast and an epiblast, which develops into the embryo itself. Continuous and dynamic transformation of pluripotency states in development coincides with the morphogenetic processes, which are involved in the formation and maturation of the epiblast. Thus, blastocyst ICM cells differ in epigenetic and transcription patterns from their daughter cells forming the peri/post-implantation epiblast. With the onset of gastrulation movements, the maturation of epiblast cells ends with their differentiation into cells of three germ layers. This review considers the historical aspects of the study of cell pluripotency, various sources of PSCs, mechanisms and signaling pathways that support self-renewal and pluripotency in PSC cultures. In addition, we summarize and conceptualize data on morphogenetic processes that are involved in the formation of naive ICM cells in vivo and the subsequent maturation of mouse and human epiblast cells associated with the transformation of their pluripotency states.

How thresholding in segmentation affects the regression performance of the linear model.

Evaluating any model underlying the control of speech requires segmenting the continuous flow of speech effectors into sequences of movements. A virtually universal practice in this segmentation is to use a velocity-based threshold which identifies a movement onset or offset as the time at which the velocity of the relevant effector breaches some threshold percentage of the maximal velocity. Depending on the threshold choice, more or less of the movement's trajectory is left in for model regression. This paper makes explicit how the choice of this threshold modulates the regression performance of a dynamical model hypothesized to govern speech movements.

A motor plan is accessible for voluntary initiation and involuntary triggering at similar short latencies.

Movement goals are an essential component of motor planning, altering voluntary and involuntary motor actions. While there have been many studies of motor planning, it is unclear if motor goals influence voluntary and involuntary movements at similar latencies. The objectives of this study were to determine how long it takes to prepare a motor action and to compare this time for voluntary and involuntary movements. We hypothesized a prepared motor action would influence voluntarily and involuntarily initiated movements at the same latency. We trained subjects to reach with a forced reaction time paradigm and used a startling acoustic stimulus (SAS) to trigger involuntary initiation of the same reaches. The time available to prepare was controlled by varying when one of four reach targets was presented. Reach direction was used to evaluate accuracy. We quantified the time between target presentation and the cue or trigger for movement initiation. We found that reaches were accurately initiated when the target was presented 48ms before the SAS and 162ms before the cue to voluntarily initiate movement. While the SAS precisely controlled the latency of movement onset, voluntary reach onset was more variable. We, therefore, quantified the time between target presentation and movement onset and found no significant difference in the time required to plan reaches initiated voluntarily or involuntarily (∆ = 8ms, p = 0.2). These results demonstrate that the time required to plan accurate reaches is similar regardless of if they are initiated voluntarily or triggered involuntarily. This finding may inform the understanding of neural pathways governing storage and access of motor plans.

Direction and distance dependency of reaching movements of lower limb.

Efficient body movement is required in our daily lives, as it facilitates responding to the external environment and producing movements in various directions and distances. While numerous studies have reported on goal-directed movements in the frontal direction during gait initiation, there is limited research on the efficient movement of the lower limbs in multiple directions and distances. Therefore, we aimed to examine changes in the kinematics of lower-limb reaching movements to determine skilled motor ability in terms of direction and distance. Sixteen adults (10 male participants) were requested to reach targets projected on the floor in seven directions and at three distances for a total of 21 points. The reaching time slowed down for the contralateral side (right foot to left-sided target) and was caused by a slower start of the toe movement. To identify the cause of this delay, we analyzed the onset of movement at each joint and found that movement to the contralateral side starts from the hip, followed by the knee, and subsequently the toe. The time-to-peak velocity was also calculated, and the motion required to reach the target in the shortest time varied depending on direction and distance. These results suggested that movement kinematics vary with direction and distance, resulting in a slower reaching time on the contralateral side. The results of our study hold promise for potential applications in sports and rehabilitation.

The Reason for the Rise in Critical Shear Stress on Sloping Beds

In sediment mechanics, the conditions for the onset of sediment movement are of particular importance. However, despite decades of research, questions remain unanswered. Thus, physical logic suggests that sediments move more easily on beds inclined in the direction of flow than on horizontal beds and that transport rates are correspondingly increased. However, numerous studies have shown that sediments require increased rather than decreased shear stress to move on sloping beds and that transport rates are lower instead of increased. Since an early publication on this issue by Ashida and Michiue in 1973, many possible effects have been suggested for this apparent contradiction. The literature almost consistently concludes that high relative roughness (d/h), i.e., low water cover (h/d), is mainly responsible for this contradictory effect. This is true for current-induced sediment transport and for the initiation of debris flow. In this paper, an analytical solution for the effect of small water coverage on the transport process is developed. Effects of low coverage also occur on beaches during wave runup and runoff and thus control the formation of steep or less steep beaches. The present paper shows that the effect of turbulence damping occurring under low water coverage plays a decisive role here.

Mechanical force regulates Sox9 expression at the developing enthesis.

Entheses transmit force from tendons and ligaments to the skeleton. Regional organization of enthesis extracellular matrix (ECM) generates differences in stiffness required for force transmission. Two key transcription factors co-expressed in entheseal tenocytes, scleraxis (Scx) and Sox9, directly control production of enthesis ECM components. Formation of embryonic craniofacial entheses in zebrafish coincides with onset of jaw movements, possibly in response to the force of muscle contraction. We show dynamic changes in scxa and sox9a mRNA levels in subsets of entheseal tenocytes that correlate with their roles in force transmission. We also show that transcription of a direct target of Scxa, Col1a, in enthesis ECM is regulated by the ratio of scxa to sox9a expression. Eliminating muscle contraction by paralyzing embryos during early stages of musculoskeletal differentiation alters relative levels of scxa and sox9a in entheses, primarily owing to increased sox9a expression. Force-dependent TGF-β (TGFβ) signaling is required to maintain this balance of scxa and sox9a expression. Thus, force from muscle contraction helps establish a balance of transcription factor expression that controls specialized ECM organization at the tendon enthesis and its ability to transmit force.

Acquired alterations in nucleus accumbens responsiveness to a cocaine-paired discriminative stimulus preceding rats’ daily cocaine consumption

Resumption of drug taking is a primary focus for substance use disorder research and can be triggered by drug-associated environmental stimuli. The Nucleus Accumbens (NAc) is a key brain region which guides motivated behavior and is implicated in resumption. Yet, there remains a pressing need to characterize NAc neurons’ responsiveness to drug associated stimuli during withdrawal and abstinence. We recorded discriminative stimulus (DS) induced NAc activity via in vivo single-unit electrophysiology in rats that self-administered cocaine. Male and female rats implanted with a jugular catheter and a microwire array in NAc Core and Shell self-administered cocaine under control of a 30s auditory DS for 6 hours per session across 14 consecutive days. Rats acquired tone discrimination within 4 sessions. To exclude pharmacological effects of circulating cocaine from all neuronal analyses, we studied changes in DS-induced firing only for trials preceding the first infusion of cocaine in each of the 14 sessions, which were defined as “pre-drug trials.” NAc neuron responses were assessed prior to tone-evoked movement onset. Responsiveness to the DS tone was exhibited throughout all sessions by the NAc Core population, but only during Early sessions by the NAc Shell population. Both Core and Shell responded selectively to the DS, i.e., more strongly on drug taking trials, or Hits, than on Missed opportunities. These findings suggest that NAc Core and Shell play distinct roles in initiating cocaine seeking prior to daily cocaine consumption, and align with reports suggesting that as drug use becomes chronic, cue-evoked activity shifts from NAc Shell to NAc Core.

Evaluation of airlift pump performance for vertical conveying of coal particles

AbstractOne of the crucial aspects of reducing air consumption when conveying particles with an airlift pump is to know the factors that affect the process of particle motion at an initial velocity of zero. To determine the influence of submergence ratio and physical properties of particles (such as size, shape, and mass) on the onset of vertical particle motion, the airlift pump was taken as the research object, and spherical glass together with irregular shaped coal were used as experimental test particles. The results show that unlike the water-solid environment, the start of particle motion in the water-air mixture does not always occur at a certain value of superficial water velocity and this value also increases with increasing submergence level. Among the parameters considered, the role of submergence ratio is much more effective than the dimensions and the shape of the particle, because by increasing submergence from 0.3 to 0.8, it is possible to reduce air consumption by up to 8 times. Based on this study the corresponding theoretical model derived by Fujimoto et al. is optimized, wherein the overall agreement between the modified theory and present experimental data is particularly good. Contrary to Fujimoto, the minimum superficial water velocity for lifting solids in the air-water mixture is not always smaller than water ambient which indicates on optimum submergence ratio higher than 0.7. Finally, a new criterion was introduced to describe the moment of onset of the particle motion as a function of the superficial fluid velocity ratio for each submergence value.

Domain wall motion at low current density in a synthetic antiferromagnet nanowire

The current-driven motion of magnetic domain walls (DWs) is the working principle of magnetic racetrack memories. In this type of spintronic technology, high current densities are used to propel DW motion in magnetic nanowires, causing significant wire heating that corresponds to wasted energy. Synthetic antiferromagnets are known to show very fast DW motion at high current densities, but lower current densities around onset of motion have received less attention. Here we use scanning transmission x-ray microscopy to study the response of DWs in a SAF multilayer to short current pulses. We observe that the DWs depin at A m−2 and move more quickly in response to 5 ns duration current pulses than in comparable multilayers that lack antiferromagnetic coupling. The results suggest that DWs in SAF structures are superior to conventional Néel DWs for low energy consumption racetrack technologies.

The archerfish predictive C-start.

A very quick decision enables hunting archerfish to secure downed prey even when they are heavily outnumbered by competing other surface-feeding fish. Based exclusively on information that is taken briefly after the onset of prey motion, the fish select a rapid C-start that turns them right towards the later point of catch. Moreover, the C-start, and not later fin strokes, already lends the fish the speed needed to arrive at just the right time. The archerfish predictive C-starts are kinematically not distinguishable from escape C-starts made by the same individual and are among the fastest C-starts known in teleost fish. The start decisions allow the fish-for ballistically falling prey-to respond accurately to any combination of the initial variables of prey movement and for any position and orientation of the responding fish. The start decisions do not show a speed-accuracy tradeoff and their accuracy is buffered against substantial changes of environmental parameters. Here, I introduce key aspects of this high-speed decision that combines speed, complexity, and precision in an unusual way.

Stimulus Onset Asynchrony Affects Weighting-related Event-related Spectral Power in Self-motion Perception.

Self-motion perception relies primarily on the integration of the visual, vestibular, proprioceptive, and somatosensory systems. There is a gap in understanding how a temporal lag between visual and vestibular motion cues affects visual-vestibular weighting during self-motion perception. The beta band is an index of visual-vestibular weighting, in that robust beta event-related synchronization (ERS) is associated with visual weighting bias, and robust beta event-related desynchronization is associated with vestibular weighting bias. The present study examined modulation of event-related spectral power during a heading judgment task in which participants attended to either visual (optic flow) or physical (inertial cues stimulating the vestibular, proprioceptive and somatosensory systems) motion cues from a motion simulator mounted on a MOOG Stewart Platform. The temporal lag between the onset of visual and physical motion cues was manipulated to produce three lag conditions: simultaneous onset, visual before physical motion onset, and physical before visual motion onset. There were two main findings. First, we demonstrated that when the attended motion cue was presented before an ignored cue, the power of beta associated with the attended modality was greater than when visual-vestibular cues were presented simultaneously or when the ignored cue was presented first. This was the case for beta ERS when the visual-motion cue was attended to, and beta event-related desynchronization when the physical-motion cue was attended to. Second, we tested whether the power of feature-binding gamma ERS (demonstrated in audiovisual and visual-tactile integration studies) increased when the visual-vestibular cues were presented simultaneously versus with temporal asynchrony. We did not observe an increase in gamma ERS when cues were presented simultaneously, suggesting that electrophysiological markers of visual-vestibular binding differ from markers of audiovisual and visual-tactile integration. All event-related spectral power reported in this study were generated from dipoles projecting from the left and right motor areas, based on the results of Measure Projection Analysis.