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The Journal of Neuroscience : the... Aug 2022The ability to perform skilled arm movements is central to everyday life, as limb impairments in common neurologic disorders such as stroke demonstrate. Skilled arm...
The ability to perform skilled arm movements is central to everyday life, as limb impairments in common neurologic disorders such as stroke demonstrate. Skilled arm movements require adaptation of motor commands based on discrepancies between desired and actual movements, called sensory errors. Studies in humans show that this involves predictive and reactive movement adaptations to the errors, and also requires a general motivation to move. How these distinct aspects map onto defined neural signals remains unclear, because of a shortage of equivalent studies in experimental animal models that permit neural-level insights. Therefore, we adapted robotic technology used in human studies to mice, enabling insights into the neural underpinnings of motivational, reactive, and predictive aspects of motor adaptation. Here, we show that forelimb motor adaptation is regulated by neurons previously implicated in motivation and arousal, but not in forelimb motor control: the hypothalamic orexin/hypocretin neurons (HONs). By studying goal-oriented mouse-robot interactions in male mice, we found distinct HON signals occur during forelimb movements and motor adaptation. Temporally-delimited optosilencing of these movement-associated HON signals impaired sensory error-based motor adaptation. Unexpectedly, optosilencing affected neither task reward or execution rates, nor motor performance in tasks that did not require adaptation, indicating that the temporally-defined HON signals studied here were distinct from signals governing general task engagement or sensorimotor control. Collectively, these results reveal a hypothalamic neural substrate regulating forelimb motor adaptation. The ability to perform skilled, adaptable movements is a fundamental part of daily life, and is impaired in common neurologic diseases such as stroke. Maintaining motor adaptation is thus of great interest, but the necessary brain components remain incompletely identified. We found that impaired motor adaptation results from disruption of cells not previously implicated in this pathology: hypothalamic orexin/hypocretin neurons (HONs). We show that temporally confined HON signals are associated with skilled movements. Without these newly-identified signals, a resistance to movement that is normally rapidly overcome leads to prolonged movement impairment. These results identify natural brain signals that enable rapid and effective motor adaptation.
Topics: Animals; Forelimb; Humans; Male; Mice; Movement; Orexins; Stroke; Upper Extremity
PubMed: 35790405
DOI: 10.1523/JNEUROSCI.0705-22.2022 -
Journal of Parkinson's Disease 2022Parkinson's disease (PD) is known to affect the brain motor circuits involving the basal ganglia (BG) and to induce, among other signs, general slowness and paucity of... (Review)
Review
Parkinson's disease (PD) is known to affect the brain motor circuits involving the basal ganglia (BG) and to induce, among other signs, general slowness and paucity of movements. In upper limb movements, PD patients show a systematic prolongation of movement duration while maintaining a sufficient level of endpoint accuracy. PD appears to cause impairments not only in movement execution, but also in movement initiation and planning, as revealed by abnormal preparatory activity of motor-related brain areas. Grasping movement is affected as well, particularly in the coordination of the hand aperture with the transport phase. In the last fifty years, numerous behavioral studies attempted to clarify the mechanisms underlying these anomalies, speculating on the plausible role that the BG-thalamo-cortical circuitry may play in normal and pathological motor control. Still, many questions remain open, especially concerning the management of the speed-accuracy tradeoff and the online feedback control. In this review, we summarize the literature results on reaching and grasping in parkinsonian patients. We analyze the relevant hypotheses on the origins of dysfunction, by focusing on the motor control aspects involved in the different movement phases and the corresponding role played by the BG. We conclude with an insight into the innovative stimulation techniques and computational models recently proposed, which might be helpful in further clarifying the mechanisms through which PD affects reaching and grasping movements.
Topics: Basal Ganglia; Hand; Humans; Motor Cortex; Movement; Parkinson Disease; Psychomotor Performance
PubMed: 35253780
DOI: 10.3233/JPD-213082 -
Physics of Life Reviews Dec 2023The control of movement in living organisms represents a fundamental task that the brain has evolved to solve. One crucial aspect is how the nervous system organizes the... (Review)
Review
The control of movement in living organisms represents a fundamental task that the brain has evolved to solve. One crucial aspect is how the nervous system organizes the transformation of sensory information into motor commands. These commands lead to muscle activation and subsequent animal movement, which can exhibit complex patterns. One example of such movement is locomotion, which involves the translation of the entire body through space. Central Pattern Generators (CPGs) are neuronal circuits that provide control signals for these movements. Compared to the intricate circuits found in the brain, CPGs can be simplified into networks of neurons that generate rhythmic activation, coordinating muscle movements. Since the 1990s, researchers have developed numerous models of locomotive circuits to simulate different types of animal movement, including walking, flying, and swimming. Initially, the primary goal of these studies was to construct biomimetic robots. However, it became apparent that simplified CPGs alone were not sufficient to replicate the diverse range of adaptive locomotive movements observed in living organisms. Factors such as sensory modulation, higher-level control, and cognitive components related to learning and memory needed to be considered. This necessitated the use of more complex, high-dimensional circuits, as well as novel materials and hardware, in both modeling and robotics. With advancements in high-power computing, artificial intelligence, big data processing, smart materials, and electronics, the possibility of designing a new generation of true bio-mimetic robots has emerged. These robots have the capability to imitate not only simple locomotion but also exhibit adaptive motor behavior and decision-making. This motivation serves as the foundation for the current review, which aims to analyze existing concepts and models of movement control systems. As an illustrative example, we focus on underwater movement and explore the fundamental biological concepts, as well as the mathematical and physical models that underlie locomotion and its various modulations.
Topics: Animals; Swimming; Robotics; Artificial Intelligence; Movement; Locomotion; Walking
PubMed: 38072505
DOI: 10.1016/j.plrev.2023.10.037 -
Perceptual and Motor Skills Aug 2020Rhythmic entrainment occurs when an auditory rhythm drives an internal movement oscillator, thus providing a continuous time reference that improves temporal and spatial...
Rhythmic entrainment occurs when an auditory rhythm drives an internal movement oscillator, thus providing a continuous time reference that improves temporal and spatial movement parameters. Entrainment processes and outcomes are well known for adults, but research is lacking for infants who might benefit from diagnosis and treatment of irregular rhythms within biological, sensorimotor, cognitive, and social domains. The present study used a combination of inertial measurement units and custom-made software to determine the amount, tempo, and regularity of movement in 28 infants aged 6-10 months while they were exposed to silence, an irregular rhythmic cue, or a regular rhythmic cue with tempo changes. We also assessed changes in the infants' movement parameters following a one-week rhythm training protocol. While results revealed no significant effect of auditory condition on amount or tempo of movement, infant movement was significantly more regular when infants were exposed to 120 bpm (beats per minute) than to an irregular rhythmic cue or a 10% faster rhythmic cue (132 bpm). Infants showed no notable changes in movement amount, tempo, or regularity following one week of training involving auditory and physical rhythm. Overall, infants seem to engage in spontaneous movements with or without auditory rhythm but may not show tempo sensitivity through their movements. Increased movement regularity suggests that 120 bpm may be a preferred tempo for infants, at which they are more likely to demonstrate well-timed movements that may reflect interval entrainment. Infants' auditory-motor systems appear not to respond to a 1-week rhythm training protocol.
Topics: Acoustic Stimulation; Auditory Perception; Female; Humans; Infant; Male; Movement; Music; Periodicity
PubMed: 32389057
DOI: 10.1177/0031512520922642 -
Proceedings of the National Academy of... Sep 2023Movement control is critical for successful interaction with our environment. However, movement does not occur in complete isolation of sensation, and this is...
Movement control is critical for successful interaction with our environment. However, movement does not occur in complete isolation of sensation, and this is particularly true of eye movements. Here, we show that the neuronal eye movement commands emitted by the superior colliculus (SC), a structure classically associated with oculomotor control, encompass a robust visual sensory representation of eye movement targets. Thus, similar saccades toward different images are associated with different saccade-related "motor" bursts. Such sensory tuning in SC saccade motor commands appeared for all image manipulations that we tested, from simple visual features to real-life object images, and it was also strongest in the most motor neurons in the deeper collicular layers. Visual-feature discrimination performance in the motor commands was also stronger than in visual responses. Comparing SC motor command feature discrimination performance to that in the primary visual cortex during steady-state gaze fixation revealed that collicular motor bursts possess a reliable perisaccadic sensory representation of the peripheral saccade target's visual appearance, exactly when retinal input is expected to be most uncertain. Our results demonstrate that SC neuronal movement commands likely serve a fundamentally sensory function.
Topics: Movement; Eye Movements; Motor Neurons; Saccades; Discrimination, Psychological
PubMed: 37695898
DOI: 10.1073/pnas.2305759120 -
Methods in Molecular Biology (Clifton,... 2023Chloroflexus is a thermophilic, filamentous, gliding bacterium. Its multicellular filaments of several hundred micrometer length move straightforward at a speed of...
Chloroflexus is a thermophilic, filamentous, gliding bacterium. Its multicellular filaments of several hundred micrometer length move straightforward at a speed of approximately 1-3 μm/s and occasionally reverse the moving direction. In liquid media, filaments glide on each other to form cell aggregates without tight adhesion. The molecular machinery on the cell surface that forces the gliding movement has not yet been identified. Here, we describe the cultivation methods to characterize the gliding motility of Chlroflexus and the microscopic assays to determine its gliding speed, reversal frequency, and cell-surface movements.
Topics: Chloroflexus; Movement; Bacteria; Cell Membrane; Cell Movement
PubMed: 36842132
DOI: 10.1007/978-1-0716-3060-0_32 -
Attention, Perception & Psychophysics Oct 2021Examining eye-movement behavior during visual search is an increasingly popular approach for gaining insights into the moment-to-moment processing that takes place when... (Review)
Review
Examining eye-movement behavior during visual search is an increasingly popular approach for gaining insights into the moment-to-moment processing that takes place when we look for targets in our environment. In this tutorial review, we describe a set of pitfalls and considerations that are important for researchers - both experienced and new to the field - when engaging in eye-movement and visual search experiments. We walk the reader through the research cycle of a visual search and eye-movement experiment, from choosing the right predictions, through to data collection, reporting of methodology, analytic approaches, the different dependent variables to analyze, and drawing conclusions from patterns of results. Overall, our hope is that this review can serve as a guide, a talking point, a reflection on the practices and potential problems with the current literature on this topic, and ultimately a first step towards standardizing research practices in the field.
Topics: Eye Movements; Humans; Movement
PubMed: 34089167
DOI: 10.3758/s13414-021-02326-w -
Computers in Biology and Medicine Apr 2020Recent advances in data analytics and computer-aided diagnostics stimulate the vision of patient-centric precision healthcare, where treatment plans are customized based... (Review)
Review
Recent advances in data analytics and computer-aided diagnostics stimulate the vision of patient-centric precision healthcare, where treatment plans are customized based on the health records and needs of every patient. In physical rehabilitation, the progress in machine learning and the advent of affordable and reliable motion capture sensors have been conducive to the development of approaches for automated assessment of patient performance and progress toward functional recovery. The presented study reviews computational approaches for evaluating patient performance in rehabilitation programs using motion capture systems. Such approaches will play an important role in supplementing traditional rehabilitation assessment performed by trained clinicians, and in assisting patients participating in home-based rehabilitation. The reviewed computational methods for exercise evaluation are grouped into three main categories: discrete movement score, rule-based, and template-based approaches. The review places an emphasis on the application of machine learning methods for movement evaluation in rehabilitation. Related work in the literature on data representation, feature engineering, movement segmentation, and scoring functions is presented. The study also reviews existing sensors for capturing rehabilitation movements and provides an informative listing of pertinent benchmark datasets. The significance of this paper is in being the first to provide a comprehensive review of computational methods for evaluation of patient performance in rehabilitation programs.
Topics: Exercise; Exercise Therapy; Humans; Movement
PubMed: 32339122
DOI: 10.1016/j.compbiomed.2020.103687 -
Annual Review of Neuroscience Jul 2020Behavior is readily classified into patterns of movements with inferred common goals-actions. Goals may be discrete; movements are continuous. Through the careful study... (Review)
Review
Behavior is readily classified into patterns of movements with inferred common goals-actions. Goals may be discrete; movements are continuous. Through the careful study of isolated movements in laboratory settings, or via introspection, it has become clear that animals can exhibit exquisite graded specification to their movements. Moreover, graded control can be as fundamental to success as the selection of which action to perform under many naturalistic scenarios: a predator adjusting its speed to intercept moving prey, or a tool-user exerting the perfect amount of force to complete a delicate task. The basal ganglia are a collection of nuclei in vertebrates that extend from the forebrain (telencephalon) to the midbrain (mesencephalon), constituting a major descending extrapyramidal pathway for control over midbrain and brainstem premotor structures. Here we discuss how this pathway contributes to the continuous specification of movements that endows our voluntary actions with vigor and grace.
Topics: Animals; Basal Ganglia; Behavior; Brain; Humans; Movement; Neural Pathways; Neurons
PubMed: 32303147
DOI: 10.1146/annurev-neuro-070918-050452 -
Journal of Neurophysiology Sep 2021On average, we redirect our gaze with a frequency at about 3 Hz. In real life, gaze shifts consist of eye and head movements. Much research has focused on how the...
On average, we redirect our gaze with a frequency at about 3 Hz. In real life, gaze shifts consist of eye and head movements. Much research has focused on how the accuracy of eye movements is monitored and calibrated. By contrast, little is known about how head movements remain accurate. I wondered whether serial dependencies between artificially induced errors in head movement targeting and the immediately following head movement might recalibrate movement accuracy. I also asked whether head movement targeting errors would influence visual localization. To this end, participants wore a head-mounted display and performed head movements to targets, which were displaced as soon as the start of the head movement was detected. I found that target displacements influenced head movement amplitudes in the same trial, indicating that participants could adjust their movement online to reach the new target location. However, I also found serial dependencies between the target displacement in trial -1 and head movements amplitudes in the following trial . I did not find serial dependencies between target displacements and visuomotor localization. The results reveal that serial dependencies recalibrate head-movement accuracy. Head movements are recalibrated by serial dependencies by errors between consecutive trials. Head movements are subject to a regression of the average target location.
Topics: Adult; Eye Movements; Female; Head Movements; Humans; Male; Psychomotor Performance; Sensorimotor Cortex; Visual Perception
PubMed: 34259049
DOI: 10.1152/jn.00231.2021