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Journal of Neurophysiology Jan 2019The bases for understanding the neuronal mechanisms that underlie the control of reach-to-grasp movements among nonhuman primates, particularly macaques, has been widely... (Review)
Review
The bases for understanding the neuronal mechanisms that underlie the control of reach-to-grasp movements among nonhuman primates, particularly macaques, has been widely studied. However, only a few kinematic descriptions of their prehensile actions are available. A thorough understanding of macaques' prehensile movements is manifestly critical, in light of their role in biomedical research as valuable models for studying neuromotor disorders and brain mechanisms, as well as for developing brain-machine interfaces to facilitate arm control. This article aims to review the current state of knowledge on the kinematics of grasping movements that macaques perform in naturalistic, seminaturalistic, and laboratory settings, to answer the following questions: Are kinematic signatures affected by the context within which the movement is performed? In what ways are kinematics of humans' and macaques' prehensile actions similar/dissimilar? Our analysis reflects the challenges involved in making comparisons across settings and species due to the heterogeneous picture in terms of the number of subjects, stimuli, conditions, and hands used. The kinematics of free-ranging macaques are characterized by distinctive features that are exhibited neither by macaques in laboratory setting nor by human subjects. The temporal incidence of key kinematic landmarks diverges significantly between species, indicating disparities in the overall organization of movement. Given such complexities, we attempt a synthesis of the extant body of evidence, intending to generate some significant implications for directions that future research might take to recognize the remaining gaps and pursue the insights and resolutions to generate an interpretation of movement kinematics that accounts for all settings and subjects.
Topics: Animals; Biomechanical Phenomena; Humans; Macaca; Motor Activity; Movement; Upper Extremity
PubMed: 30427765
DOI: 10.1152/jn.00598.2018 -
Scientific Reports Nov 2021Although the engagement of sensorimotor cortices in movement is well documented, the functional relevance of brain activity patterns remains ambiguous. Especially, the... (Clinical Trial)
Clinical Trial
Although the engagement of sensorimotor cortices in movement is well documented, the functional relevance of brain activity patterns remains ambiguous. Especially, the cortical engagement specific to the pre-, within-, and post-movement periods is poorly understood. The present study addressed this issue by examining sensorimotor EEG activity during the performance as well as STOP-signal cued suppression of movements pertaining to two distinct classes, namely, discrete vs. ongoing rhythmic movements. Our findings indicate that the lateralized readiness potential (LRP), which is classically used as a marker of pre-movement processing, indexes multiple pre- and in- movement-related brain dynamics in a movement-class dependent fashion. In- and post-movement event-related (de)synchronization (ERD/ERS) observed in the Mu (8-13 Hz) and Beta (15-30 Hz) frequency ranges were associated with estimated brain sources in both motor and somatosensory cortical areas. Notwithstanding, Beta ERS occurred earlier following cancelled than actually performed movements. In contrast, Mu power did not vary. Whereas Beta power may reflect the evaluation of the sensory predicted outcome, Mu power might engage in linking perception to action. Additionally, the rhythmic movement forced stop (only) showed a post-movement Mu/Beta rebound, which might reflect an active "clearing-out" of the motor plan and its feedback-based online control. Overall, the present study supports the notion that sensorimotor EEG modulations are key markers to investigate control or executive processes, here initiation and inhibition, which are exerted when performing distinct movement classes.
Topics: Adult; Beta Rhythm; Female; Humans; Male; Movement; Sensorimotor Cortex
PubMed: 34785710
DOI: 10.1038/s41598-021-01368-2 -
Optometry and Vision Science : Official... Jan 2022Stereothresholds increase in the presence of disconjugate image motion, whether this motion results from vergence errors that occur during active head movements or is...
SIGNIFICANCE
Stereothresholds increase in the presence of disconjugate image motion, whether this motion results from vergence errors that occur during active head movements or is imposed externally.
PURPOSE
During rapid voluntary oscillations of the head, vergence eye position has been reported to vary with a peak-to-peak amplitude of about 0.5°-a considerably greater amplitude than when the head is still. Concurrently, stereopsis was reported to be unaffected by voluntary head motion. In the present study, we measured stereothresholds during voluntary side-to-side head movements and during imposed disconjugate image motion with the head stationary, to simulate that produced during active head movement.
METHODS
Stereothresholds were measured for a pair of 30-arcmin bright vertical lines presented on an oscilloscope and viewed through a custom mirror haploscope. Data were obtained from four normal observers during voluntary side-to-side head movements at temporal frequencies up to 1.5 Hz and also while the head remained still. In addition, stereothresholds were measured with the head stationary when opposite rotations of the galvanometer-driven mirrors in each channel of the haploscope created disconjugate image motion to simulate vergence variability during active head movement.
RESULTS
During head motion, average stereothresholds increased from about 10 to about 14 arcsec. With imposed disconjugate image motion, stereothresholds rose systematically to about 35 arcsec when the peak-to-peak motion amplitude was 0.5°. Stereothresholds depend primarily on the amplitude of imposed motion and only marginally on variations of the disjunctive-motion wave form.
CONCLUSIONS
Stereothresholds are elevated modestly during active head movements. The results obtained with imposed disjunctive image motion are consistent with a previously proposal that stereothresholds vary according to the unsigned, time-averaged deviation of the stereotarget from the plane of the horopter.
Topics: Depth Perception; Eye Movements; Head; Head Movements; Humans; Motion Perception
PubMed: 34882606
DOI: 10.1097/OPX.0000000000001831 -
Advances in Experimental Medicine and... 2016In order to reliably produce intelligible speech or fluently play a melody on a piano, learning the precise timing of muscle activations is essential. Surprisingly, the... (Review)
Review
In order to reliably produce intelligible speech or fluently play a melody on a piano, learning the precise timing of muscle activations is essential. Surprisingly, the fundamental question of how memories of complex temporal dynamics of movement are stored across the brain is still unresolved. This review outlines the constraints that determine whether and how the timing of skilled movements is represented in the central nervous system and introduces different computational and neural mechanisms that can be harnessed for temporal encoding. It concludes by proposing a schematic model of how these different mechanisms may complement and interact with each other in fast feedback loops to achieve skilled motor timing.
Topics: Brain; Humans; Learning; Movement; Psychomotor Performance
PubMed: 28035559
DOI: 10.1007/978-3-319-47313-0_3 -
Journal of Visualized Experiments : JoVE Mar 2023Through the purposeful stimulation and recording of eye movements, the fundamental characteristics of the underlying neural mechanisms of eye movements can be observed....
Through the purposeful stimulation and recording of eye movements, the fundamental characteristics of the underlying neural mechanisms of eye movements can be observed. VisualEyes2020 (VE2020) was developed based on the lack of customizable software-based visual stimulation available for researchers that does not rely on motors or actuators within a traditional haploscope. This new instrument and methodology have been developed for a novel haploscope configuration utilizing both eye tracking and autorefractor systems. Analysis software that enables the synchronized analysis of eye movement and accommodative responses provides vision researchers and clinicians with a reproducible environment and shareable tool. The Vision and Neural Engineering Laboratory's (VNEL) Eye Movement Analysis Program (VEMAP) was established to process recordings produced by VE2020's eye trackers, while the Accommodative Movement Analysis Program (AMAP) was created to process the recording outputs from the corresponding autorefractor system. The VNEL studies three primary stimuli: accommodation (blur-driven changes in the convexity of the intraocular lens), vergence (inward, convergent rotation and outward, divergent rotation of the eyes), and saccades (conjugate eye movements). The VEMAP and AMAP utilize similar data flow processes, manual operator interactions, and interventions where necessary; however, these analysis platforms advance the establishment of an objective software suite that minimizes operator reliance. The utility of a graphical interface and its corresponding algorithms allow for a broad range of visual experiments to be conducted with minimal required prior coding experience from its operator(s).
Topics: Eye Movements; Saccades; Accommodation, Ocular; Movement
PubMed: 36939267
DOI: 10.3791/64808 -
Biology Open Mar 2023Rhythmic limb multi-joint movement like locomotion is controlled by intralimb coordination. Intralimb coordination changes entail immediate alterations in movement...
Rhythmic limb multi-joint movement like locomotion is controlled by intralimb coordination. Intralimb coordination changes entail immediate alterations in movement patterns and be related with cerebellum function. Synchronized cerebellum activity has known to modulate the frequency of walking, but not known the effect of only intralimb coordination. The purpose of this study was to reveal the effect of synchronized and unsynchronized cerebellum activity on the coordination of multi-joint movements of the unilateral leg in young and elderly people. To achieve our purpose, we applied synchronized and unsynchronized cerebellum transcranial alternating current stimulation during cyclic unilateral multi-joint movement by visual tracking task. The results showed that the reduction in comprehensive synchrony between targets and movements through trials had no significant differences under all stimulus conditions in young and elderly people. However, the reduction in variation of synchronization through trials was significantly smaller under the synchronized transcranial alternating current stimulation condition in both young and elderly groups. Variation of synchronization was remarkably reduced under the synchronized transcranial alternating current stimulation condition for the elderly group. This study showed that movement-synchronized cerebellum activity contributes to reducing fluctuations in movement synchrony by coordinating unilateral multi-joint movements. Moreover, this reduction was remarkable in the elderly group.
Topics: Humans; Adult; Aged; Locomotion; Joints; Walking
PubMed: 36688850
DOI: 10.1242/bio.059776 -
Social Cognitive and Affective... Mar 2023Although the ability to detect the actions of other living beings is key for adaptive social behavior, it is still unclear if biological motion perception is specific to...
Although the ability to detect the actions of other living beings is key for adaptive social behavior, it is still unclear if biological motion perception is specific to human stimuli. Biological motion perception involves both bottom-up processing of movement kinematics ('motion pathway') and top-down reconstruction of movement from changes in the body posture ('form pathway'). Previous research using point-light displays has shown that processing in the motion pathway depends on the presence of a well-defined, configural shape (objecthood) but not necessarily on whether that shape depicts a living being (animacy). Here, we focused on the form pathway. Specifically, we combined electroencephalography (EEG) frequency tagging with apparent motion to study how objecthood and animacy influence posture processing and the integration of postures into movements. By measuring brain responses to repeating sequences of well-defined or pixelated images (objecthood), depicting human or corkscrew agents (animacy), performing either fluent or non-fluent movements (movement fluency), we found that movement processing was sensitive to objecthood but not animacy. In contrast, posture processing was sensitive to both. Together, these results indicate that reconstructing biological movements from apparent motion sequences requires a well-defined but not necessarily an animate shape. Instead, stimulus animacy appears to be relevant only for posture processing.
Topics: Humans; Photic Stimulation; Movement; Motion Perception; Posture; Social Behavior
PubMed: 36905406
DOI: 10.1093/scan/nsad014 -
Scientific Reports May 2022Existing models of human walking use low-level reflexes or neural oscillators to generate movement. While appropriate to generate the stable, rhythmic movement patterns...
Existing models of human walking use low-level reflexes or neural oscillators to generate movement. While appropriate to generate the stable, rhythmic movement patterns of steady-state walking, these models lack the ability to change their movement patterns or spontaneously generate new movements in the specific, goal-directed way characteristic of voluntary movements. Here we present a neuromuscular model of human locomotion that bridges this gap and combines the ability to execute goal directed movements with the generation of stable, rhythmic movement patterns that are required for robust locomotion. The model represents goals for voluntary movements of the swing leg on the task level of swing leg joint kinematics. Smooth movements plans towards the goal configuration are generated on the task level and transformed into descending motor commands that execute the planned movements, using internal models. The movement goals and plans are updated in real time based on sensory feedback and task constraints. On the spinal level, the descending commands during the swing phase are integrated with a generic stretch reflex for each muscle. Stance leg control solely relies on dedicated spinal reflex pathways. Spinal reflexes stimulate Hill-type muscles that actuate a biomechanical model with eight internal joints and six free-body degrees of freedom. The model is able to generate voluntary, goal-directed reaching movements with the swing leg and combine multiple movements in a rhythmic sequence. During walking, the swing leg is moved in a goal-directed manner to a target that is updated in real-time based on sensory feedback to maintain upright balance, while the stance leg is stabilized by low-level reflexes and a behavioral organization switching between swing and stance control for each leg. With this combination of reflex-based stance leg and voluntary, goal-directed control of the swing leg, the model controller generates rhythmic, stable walking patterns in which the swing leg movement can be flexibly updated in real-time to step over or around obstacles.
Topics: Biomechanical Phenomena; Electromyography; Humans; Locomotion; Movement; Muscle, Skeletal; Reflex; Walking
PubMed: 35581211
DOI: 10.1038/s41598-022-11102-1 -
PloS One 2024Collectively searching animals might be expected to coordinate with their groupmates to cover ground more evenly or efficiently than uncoordinated groups. Communication...
Collectively searching animals might be expected to coordinate with their groupmates to cover ground more evenly or efficiently than uncoordinated groups. Communication can lead to coordination in many ways. Previous work in ants suggests that chemical 'footprints', left behind by individuals as they walk, might serve this function by modulating the movement patterns of following ants. Here, we test this hypothesis by considering the two predictions that, first, ants may turn away from sites with higher footprint concentrations (klinotaxis), or, second, that they may change their turning patterns depending on the presence of footprints (klinokinesis). We tracked 5 whole colonies of Temnothorax rugatulus ants in a large arena over 5h. We approximated the footprint concentration by summing ant visitations for each point in the arena and calculated the speed and local path straightness for each point of the ant trajectories. We counterintuitively find that ants walk slightly faster and straighter in areas with fewer footprints. This is partially explained by the effect that ants who start out from the nest walking straighter move on average further away from the nest, where there are naturally fewer footprints, leading to an apparent relationship between footprint density and straightness However, ants walk slightly faster and straighter off footprints even when controlling for this effect. We tested for klinotaxis by calculating the footprint concentrations perceived by the left and right antennae of ants and found no evidence for a turning-away (nor turning-towards) behavior. Instead, we found noticeable effects of environmental idiosyncrasies on the behavior of ants which are likely to overpower any reactions to pheromones. Our results indicate that search density around an ant colony is affected by several independent processes, including individual differences in movement pattern, local spatial heterogeneities, and ants' reactions to chemical footprints. The multitude of effects illustrates that non-communicative coordination, individual biases and interactions with the environment might have a greater impact on group search efficiency and exploratory movements than pheromone communication.
Topics: Ants; Animals; Movement; Behavior, Animal; Walking
PubMed: 38652728
DOI: 10.1371/journal.pone.0299432 -
Scientific Reports Nov 2023Dynamic visual acuity (DVA) is crucial for the perception of moving objects. While traditional DVA assessment tools predominantly focus on horizontal movements, the...
Dynamic visual acuity (DVA) is crucial for the perception of moving objects. While traditional DVA assessment tools predominantly focus on horizontal movements, the evaluation of vertical DVA remains unstandardized. Consequently, the disparities between vertical and horizontal DVAs are yet to be thoroughly investigated. Therefore, we designed a system capable of conducting multidirectional DVA tests and eye movement measurements. During the experiments, the participants identified the gap direction of the Landolt-C ring moving either horizontally or vertically. The speed of movement decelerated from its maximum as a high-speed infrared camera captured the pupil movements of the left eye at 500 fps. We conducted tests on 15 healthy university students (aged [Formula: see text] years) and measured vertical and horizontal DVAs five times each. DVA was deduced from the Landolt-C ring speed with accurate gap direction responses, and eye movement was assessed based on the total gaze movement distance. The results revealed superior DVA and eye movement in the horizontal direction compared with the vertical direction ([Formula: see text]). This highlights the anisotropic characteristics of DVA and eye movement. The proposed system has the potential for multidirectional dynamic vision evaluation and training in clinical scenarios.
Topics: Humans; Aged; Visual Acuity; Eye Movements; Movement; Vision Tests; Eye Movement Measurements
PubMed: 38017190
DOI: 10.1038/s41598-023-48292-1