-
Annual Review of Neuroscience Jul 2022The brain plans and executes volitional movements. The underlying patterns of neural population activity have been explored in the context of movements of the eyes,... (Review)
Review
The brain plans and executes volitional movements. The underlying patterns of neural population activity have been explored in the context of movements of the eyes, limbs, tongue, and head in nonhuman primates and rodents. How do networks of neurons produce the slow neural dynamics that prepare specific movements and the fast dynamics that ultimately initiate these movements? Recent work exploits rapid and calibrated perturbations of neural activity to test specific dynamical systems models that are capable of producing the observed neural activity. These joint experimental and computational studies show that cortical dynamics during motor planning reflect fixed points of neural activity (attractors). Subcortical control signals reshape and move attractors over multiple timescales, causing commitment to specific actions and rapid transitions to movement execution. Experiments in rodents are beginning to reveal how these algorithms are implemented at the level of brain-wide neural circuits.
Topics: Algorithms; Animals; Brain; Motor Cortex; Movement; Neurons
PubMed: 35316610
DOI: 10.1146/annurev-neuro-092021-121730 -
Annual Review of Vision Science Sep 2017Investigation of natural behavior has contributed a number of insights to our understanding of visual guidance of actions by highlighting the importance of behavioral... (Review)
Review
Investigation of natural behavior has contributed a number of insights to our understanding of visual guidance of actions by highlighting the importance of behavioral goals and focusing attention on how vision and action play out in time. In this context, humans make continuous sequences of sensory-motor decisions to satisfy current behavioral goals, and the role of vision is to provide the relevant information for making good decisions in order to achieve those goals. This conceptualization of visually guided actions as a sequence of sensory-motor decisions has been formalized within the framework of statistical decision theory, which structures the problem and provides the context for much recent progress in vision and action. Components of a good decision include the task, which defines the behavioral goals, the rewards and costs associated with those goals, uncertainty about the state of the world, and prior knowledge.
Topics: Decision Making; Eye Movements; Feedback, Sensory; Goals; Memory; Motivation; Motor Activity; Movement; Reward; Sensorimotor Cortex; Visual Perception
PubMed: 28715958
DOI: 10.1146/annurev-vision-102016-061437 -
Journal of Bodywork and Movement... Oct 2018Functional movements are designed to look at how our body functions in different environments. Power is often performed in the vertical plane and very stable positions...
Functional movements are designed to look at how our body functions in different environments. Power is often performed in the vertical plane and very stable positions of the body. Both life and sport require a great deal more complexity of movement with direction and deceleration playing key roles. The Kettlebell Lunge Clean (KLC) exercise is a safe and powerful exercise to teach these qualities and progress the power development and force absorption capabilities of the individual.
Topics: Biomechanical Phenomena; Humans; Movement; Resistance Training
PubMed: 30368345
DOI: 10.1016/j.jbmt.2018.09.079 -
Journal of Neuroengineering and... Dec 2015Quantitative measures of smoothness play an important role in the assessment of sensorimotor impairment and motor learning. Traditionally, movement smoothness has been... (Review)
Review
Quantitative measures of smoothness play an important role in the assessment of sensorimotor impairment and motor learning. Traditionally, movement smoothness has been computed mainly for discrete movements, in particular arm, reaching and circle drawing, using kinematic data. There are currently very few studies investigating smoothness of rhythmic movements, and there is no systematic way of analysing the smoothness of such movements. There is also very little work on the smoothness of other movement related variables such as force, impedance etc. In this context, this paper presents the first step towards a unified framework for the analysis of smoothness of arbitrary movements and using various data. It starts with a systematic definition of movement smoothness and the different factors that influence smoothness, followed by a review of existing methods for quantifying the smoothness of discrete movements. A method is then introduced to analyse the smoothness of rhythmic movements by generalising the techniques developed for discrete movements. We finally propose recommendations for analysing smoothness of any general sensorimotor behaviour.
Topics: Biomechanical Phenomena; Electrophysiology; Humans; Movement
PubMed: 26651329
DOI: 10.1186/s12984-015-0090-9 -
Psychonomic Bulletin & Review Aug 2017Sharing numerous characteristics with suppression in the other senses, tactile suppression is a reliable phenomenon that accompanies movement. By investigating the... (Review)
Review
Sharing numerous characteristics with suppression in the other senses, tactile suppression is a reliable phenomenon that accompanies movement. By investigating the simplest of movements (e.g., finger flexions), early research tried to explain the origins of the phenomenon in terms of motor command generation together with sensory reafference. Here, we review recent research that has delved into (naturalistic) goal-directed movements. In connection with goal-directed movement, tactile suppression is evident as a decrease in behavioural performance measured shortly prior to, and during, movement execution. It is also reflected in a consistent response bias highlighting the (perceptual) uncertainty of the movement. Goal-directed movement supports the forward model and establishes contextual influences as the defining influences on tactile suppression. Depending on the task at hand, people prioritize a certain percept during movement. Future research, we argue, should focus on studying naturalistic movements, or sequences of movements, that share a common meaning or goal.
Topics: Goals; Humans; Movement; Psychomotor Performance; Touch Perception
PubMed: 27896632
DOI: 10.3758/s13423-016-1203-6 -
Annual Review of Neuroscience Jul 2019Neuronal circuits that regulate movement are distributed throughout the nervous system. The brainstem is an important interface between upper motor centers involved in... (Review)
Review
Neuronal circuits that regulate movement are distributed throughout the nervous system. The brainstem is an important interface between upper motor centers involved in action planning and circuits in the spinal cord ultimately leading to execution of body movements. Here we focus on recent work using genetic and viral entry points to reveal the identity of functionally dedicated and frequently spatially intermingled brainstem populations essential for action diversification, a general principle conserved throughout evolution. Brainstem circuits with distinct organization and function control skilled forelimb behavior, orofacial movements, and locomotion. They convey regulatory parameters to motor output structures and collaborate in the construction of complex natural motor behaviors. Functionally tuned brainstem neurons for different actions serve as important integrators of synaptic inputs from upstream centers, including the basal ganglia and cortex, to regulate and modulate behavioral function in different contexts.
Topics: Animals; Brain Stem; Humans; Locomotion; Motor Neurons; Movement; Neural Pathways; Spinal Cord
PubMed: 31283898
DOI: 10.1146/annurev-neuro-070918-050201 -
Sleep Medicine Clinics Dec 2016Currently, 2 sets of similar rules for recording and scoring leg movement (LM) exist, including periodic LM during sleep (PLMS) and periodic LM during wakefulness. The... (Review)
Review
Currently, 2 sets of similar rules for recording and scoring leg movement (LM) exist, including periodic LM during sleep (PLMS) and periodic LM during wakefulness. The former were published in 2006 by a task force of the International Restless Legs Syndrome Study Group, and the second in 2007 by the American Academy of Sleep Medicine. This article reviews the basic recording methods, scoring rules, and computer-based programs for PLMS. Less frequent LM activities, such as alternating leg muscle activation, hypnagogic foot tremor, high-frequency LMs, and excessive fragmentary myoclonus are briefly described.
Topics: Extremities; Humans; Movement; Polysomnography; Sleep
PubMed: 28118866
DOI: 10.1016/j.jsmc.2016.08.005 -
Multisensory Research Oct 2023Head movement relative to the stationary environment gives rise to congruent vestibular and visual optic-flow signals. The resulting perception of a stationary visual...
Head movement relative to the stationary environment gives rise to congruent vestibular and visual optic-flow signals. The resulting perception of a stationary visual environment, referred to herein as stationarity perception, depends on mechanisms that compare visual and vestibular signals to evaluate their congruence. Here we investigate the functioning of these mechanisms and their dependence on fixation behavior as well as on the active versus passive nature of the head movement. Stationarity perception was measured by modifying the gain on visual motion relative to head movement on individual trials and asking subjects to report whether the gain was too low or too high. Fitting a psychometric function to the data yields two key parameters of performance. The mean is a measure of accuracy, and the standard deviation is a measure of precision. Experiments were conducted using a head-mounted display with fixation behavior monitored by an embedded eye tracker. During active conditions, subjects rotated their heads in yaw ∼15 deg/s over ∼1 s. Each subject's movements were recorded and played back via rotating chair during the passive condition. During head-fixed and scene-fixed fixation the fixation target moved with the head or scene, respectively. Both precision and accuracy were better during active than passive head movement, likely due to increased precision on the head movement estimate arising from motor prediction and neck proprioception. Performance was also better during scene-fixed than head-fixed fixation, perhaps due to decreased velocity of retinal image motion and increased precision on the retinal image motion estimate. These results reveal how the nature of head and eye movements mediate encoding, processing, and comparison of relevant sensory and motor signals.
Topics: Humans; Eye Movements; Head Movements; Motion Perception; Motion; Proprioception; Rotation
PubMed: 37903493
DOI: 10.1163/22134808-bja10111 -
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