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Perceptual and Motor Skills Oct 2022Harmonious voluntary movements require efficiency in their planning and execution. Throughout middle childhood structural changes in the central nervous and...
Harmonious voluntary movements require efficiency in their planning and execution. Throughout middle childhood structural changes in the central nervous and musculoskeletal systems influence these processes and resultant motor behavior. In this study, we evaluated the characteristics of the motor planning and executing of aiming movements directed at targets located in different positions in space in children aged 7, 9, and 11 years. We divided 43 right-handed children, into three age groups and instructed them to perform aiming movements directed at targets using a stylus on a digital tablet. The children performed the movement with their dominant upper limbs from a starting point towards targets positioned ipsilaterally or contralaterally to this dominant limb. We analyzed temporal and spatial variables of motor performance. Younger (7-year-old) children made more errors in the initial movement direction and more frequently corrected their movements during task execution when compared to 9- and 11-year-old children who did not differ from each other. All age groups were similar in movement accuracy and precision. Movements toward contralateral targets were slower and more accurate than movements toward ipsilateral targets for all groups. These results show that performing aiming movements develop with the onset of middle childhood.
Topics: Child; Functional Laterality; Hand; Humans; Movement; Psychomotor Performance; Upper Extremity
PubMed: 35790415
DOI: 10.1177/00315125221112243 -
Current Biology : CB Jun 2020Across vertebrates, eye movements serve the dual purpose of image stabilization during head or body movement, and gaze relocation. A new study has measured head and...
Across vertebrates, eye movements serve the dual purpose of image stabilization during head or body movement, and gaze relocation. A new study has measured head and bilateral eye movements in freely moving mice, providing a detailed characterization of dynamic gaze behavior.
Topics: Animals; Eye Movements; Head; Mice; Movement; Vision, Ocular
PubMed: 32516609
DOI: 10.1016/j.cub.2020.04.063 -
Tracking and Classification of Head Movement for Augmentative and Alternative Communication Systems.Sensors (Basel, Switzerland) Jan 2022The use of assistive technologies can mitigate or reduce the challenges faced by individuals with motor disabilities to use computer systems. However, those who feature...
The use of assistive technologies can mitigate or reduce the challenges faced by individuals with motor disabilities to use computer systems. However, those who feature severe involuntary movements often have fewer options at hand. This work describes an application that can recognize the user's head using a conventional webcam, track its motion, model the desired functional movement, and recognize it to enable the use of a virtual keyboard. The proposed classifier features a flexible structure and may be personalized for different user need. Experimental results obtained with participants with no neurological disorders have shown that classifiers based on Hidden Markov Models provided similar or better performance than a classifier based on position threshold. However, motion segmentation and interpretation modules were sensitive to involuntary movements featured by participants with cerebral palsy that took part in the study.
Topics: Cerebral Palsy; Communication; Head Movements; Humans; Movement; Self-Help Devices; User-Computer Interface
PubMed: 35062395
DOI: 10.3390/s22020435 -
The European Journal of Neuroscience Apr 2023Periodicity is a fundamental property of biological systems, including human movement systems. Periodic movements support displacements of the body in the environment as...
Periodicity is a fundamental property of biological systems, including human movement systems. Periodic movements support displacements of the body in the environment as well as interactions and communication between individuals. Here, we use electroencephalography (EEG) to investigate the neural tracking of visual periodic motion, and more specifically, the relevance of spatiotemporal information contained at and between their turning points. We compared EEG responses to visual sinusoidal oscillations versus nonlinear Rayleigh oscillations, which are both typical of human movements. These oscillations contain the same spatiotemporal information at their turning points but differ between turning points, with Rayleigh oscillations having an earlier peak velocity, shown to increase an individual's capacity to produce accurately synchronized movements. EEG analyses highlighted the relevance of spatiotemporal information between the turning points by showing that the brain precisely tracks subtle differences in velocity profiles, as indicated by earlier EEG responses for Rayleigh oscillations. The results suggest that the brain is particularly responsive to velocity peaks in visual periodic motion, supporting their role in conveying behaviorally relevant timing information at a neurophysiological level. The results also suggest key functions of neural oscillations in the Alpha and Beta frequency bands, particularly in the right hemisphere. Together, these findings provide insights into the neural mechanisms underpinning the processing of visual periodic motion and the critical role of velocity peaks in enabling proficient visuomotor synchronization.
Topics: Humans; Motion; Brain; Movement; Electroencephalography; Motion Perception
PubMed: 36788113
DOI: 10.1111/ejn.15934 -
Nature Communications Jul 2023The classification of neuronal subpopulations has significantly advanced, yet its relevance for behavior remains unclear. The highly organized flocculus of the...
The classification of neuronal subpopulations has significantly advanced, yet its relevance for behavior remains unclear. The highly organized flocculus of the cerebellum, known to fine-tune multi-axial eye movements, is an ideal substrate for the study of potential functions of neuronal subpopulations. Here, we demonstrate that its recently identified subpopulations of 9+ and 9- Purkinje cells exhibit an intermediate Aldolase C expression and electrophysiological profile, providing evidence for a graded continuum of intrinsic properties among PC subpopulations. By identifying and utilizing two Cre-lines that genetically target these floccular domains, we show with high spatial specificity that these subpopulations of Purkinje cells participate in separate micromodules with topographically organized connections. Finally, optogenetic excitation of the respective subpopulations results in movements around the same axis in space, yet with distinct kinematic profiles. These results indicate that Purkinje cell subpopulations integrate in discrete circuits and mediate particular parameters of single movements.
Topics: Purkinje Cells; Biomechanical Phenomena; Eye Movements; Cerebellum; Movement
PubMed: 37468512
DOI: 10.1038/s41467-023-40111-5 -
Biological Cybernetics Aug 2022In human upper-arm reaching movements, the variance of the hand position increases until the middle of the movement and then decreases toward the endpoint. Such decrease...
In human upper-arm reaching movements, the variance of the hand position increases until the middle of the movement and then decreases toward the endpoint. Such decrease in positional variance has been suggested as an evidence to support the hypothesis that our nervous system uses feedback control, rather than feedforward control, for arm reaching tasks. In this study, we computed the optimal trajectories based on feedforward control under several criteria for a one-link two-muscle arm model with considering the stochastic property of muscle activities in order to reexamine the hypothesis. The results showed that the feedforward control also represents the decrease in positional variance in the latter half of the movement when the control signal is planned under the minimum energy cost and minimum variance models. Furthermore, the optimal trajectory that minimizes energy cost represents not only the decrease in positional variance but also many other characteristics of the human reaching movements, e.g., the three-phasic activity of antagonistic muscle, bell-shaped speed curve, N-shaped equilibrium trajectory, and bimodal profile of joint stiffness. These results suggest that minimum energy cost model well expresses the characteristics of hand reaching movements, and our central nervous system would make use of not only a feedback control but also feedforward control.
Topics: Feedback; Hand; Humans; Models, Biological; Movement
PubMed: 35662362
DOI: 10.1007/s00422-022-00939-4 -
Human Movement Science Jun 2022Performing coordinated bimanual movements, that is, movements with two hands simultaneously, is a requirement in many activities. At the same time, these movements are...
Performing coordinated bimanual movements, that is, movements with two hands simultaneously, is a requirement in many activities. At the same time, these movements are subject to temporal and spatial constraints. Here, we focus on the constraints that become observable when pointing movements of different (asymmetric) rather than same (symmetric) amplitudes have to be executed ("spatial interference effect"). The respective performance costs are larger when the stimuli used to indicate the movement targets are symbolic compared with when the endpoints of the movements are cued directly. Previous studies have thus concluded that the source of spatial interference is both 'cognitive' and 'motoric', or more precisely occurs during response selection as well as motor programming. We here asked whether the contribution from motor programming is motoric in the sense as envisaged in dual-task models, that is, whether it can run in parallel to, and interference-free with, other processing stages. In two PRP experiments, Task 1 was bimanual pointing and Task 2 was auditory pitch-discrimination. Based on the effect propagation-logic, the results suggest that the motor programming contribution to bimanual interference also taps into capacity-limited resources and cannot be construed as running in parallel as assumed for the motor stage in dual-task models.
Topics: Functional Laterality; Hand; Humans; Movement; Psychomotor Performance; Reaction Time
PubMed: 35313236
DOI: 10.1016/j.humov.2022.102939 -
Human Brain Mapping Dec 2023Self-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...
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.
Topics: Humans; Evoked Potentials; Electroencephalography; Movement; Fingers; Upper Extremity
PubMed: 37792296
DOI: 10.1002/hbm.26506 -
Journal of Neurotrauma May 2023After incomplete spinal cord injury (iSCI), the control of lower extremity movements may be affected by impairments in descending corticospinal tract function. Previous...
After incomplete spinal cord injury (iSCI), the control of lower extremity movements may be affected by impairments in descending corticospinal tract function. Previous iSCI studies demonstrated relatively well-preserved movement control during simple alternating dorsiflections and plantar flexions albeit with severely reduced motor strength and range of motion. This task, however, required comparably limited fine motor control, impeding the sensitivity to assess the modulatory capacity of corticospinal control. Therefore, we introduced a more challenging ankle motor task necessitating complex and dynamic feedback-based movement adjustments to modulate corticospinal drive. Nineteen individuals with iSCI and 22 control subjects performed two different ankle movement tasks: (1) a regular, auditory-guided ankle movement task at a constant frequency as baseline assessment and (2) an irregular, visually guided ankle movement task following a pre-defined trajectory as a more challenging motor task. Both tasks were performed separately and in a randomized order. Electromyography (EMG) and kinematic data were recorded. The EMG frequency characteristics were investigated using wavelet transformations. Control participants exhibited a shift of relative EMG intensity from higher (>100 Hz) to lower frequencies (20-60 Hz) comparing the regular with the irregular movement task. There is evidence that EMG activity within these lower frequencies comprise information on corticospinal drive. The EMG frequency shift was less pronounced for the less impaired leg and absent for the more impaired leg of individuals with iSCI. The precision error during the irregular task was significantly higher for individuals with iSCI (more impaired leg: 12.34 ± 11.14%; less impaired leg: 6.93 ± 2.74%) compared with control participants (4.10 ± 0.84%). These results, along with the walking performance, correlated well with the delta frequency shift between the regular and irregular movement task in the 38 Hz band (corticospinal drive frequency) in the iSCI group, suggesting that task performance is related to the capacity to modulate corticospinal control. The irregular movement task holds promise as a tool for revealing further insights into corticospinal control of single-joint movements. It may serve as a surrogate marker for the assessment of modulatory capacity and the integrity of corticospinal control in individuals with iSCI early after injury and throughout rehabilitation.
Topics: Humans; Ankle; Walking; Spinal Cord Injuries; Electromyography; Movement
PubMed: 36029211
DOI: 10.1089/neu.2022.0205 -
Movement Disorders : Official Journal... Mar 2023Motor symptoms in functional movement disorders (FMDs) are experienced as involuntary but share characteristics of voluntary action. Clinical and experimental evidence...
BACKGROUND
Motor symptoms in functional movement disorders (FMDs) are experienced as involuntary but share characteristics of voluntary action. Clinical and experimental evidence indicate alterations in monitoring, control, and subjective experience of self-performed movements.
OBJECTIVE
The objective of this study was to test the prediction that FMDs are associated with a reduced ability to make accurate (metacognitive) judgments about self-performed movements.
METHODS
We compared 24 patients with FMD (including functional gait disturbance, functional tremor, and functional tics) with 24 age- and sex-matched healthy control subjects in a novel visuomotor-metacognitive paradigm. Participants performed target-directed movements on a graphics tablet with restricted visual feedback, decided which of two visually presented trajectories was closer to their preceding movement, and reported their confidence in the visuomotor decision. We quantified individual metacognitive performance as participants' ability to assign high confidence preferentially to correct visuomotor decisions.
RESULTS
Patients and control subjects showed comparable motor performance, response accuracy, and use of the confidence scale. However, visuomotor sensitivity in the trajectory judgment was reduced in patients with FMD compared with healthy control subjects. Moreover, metacognitive performance was impaired in patients, that is, their confidence ratings were less predictive of the correctness of visuomotor decisions. Exploratory subgroup analyses suggest metacognitive deficits to be most pronounced in patients with a functional gait disturbance or functional tremor.
CONCLUSIONS
Patients with FMD exhibited deficits both when making visuomotor decisions about their own movements and in the metacognitive evaluation of these decisions. Reduced metacognitive insight into voluntary motor control may play a role in FMD pathophysiology and could lay the groundwork for new treatment strategies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Humans; Metacognition; Tremor; Conversion Disorder; Judgment; Movement; Movement Disorders
PubMed: 36606550
DOI: 10.1002/mds.29303