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Nature Reviews. Neuroscience Jun 2022The execution and learning of diverse movements involve neuronal networks distributed throughout the nervous system. The brainstem and basal ganglia are key for... (Review)
Review
The execution and learning of diverse movements involve neuronal networks distributed throughout the nervous system. The brainstem and basal ganglia are key for processing motor information. Both harbour functionally specialized populations stratified on the basis of axonal projections, synaptic inputs and gene expression, revealing a correspondence between circuit anatomy and function at a high level of granularity. Neuronal populations within both structures form multistep processing chains dedicated to the execution of specific movements; however, the connectivity and communication between these two structures is only just beginning to be revealed. The brainstem and basal ganglia are also embedded into wider networks and into systems-level loops. Important networking components include broadcasting neurons in the cortex, cerebellar output neurons and midbrain dopaminergic neurons. Action-specific circuits can be enhanced, vetoed, work in synergy or competition with others, or undergo plasticity to allow adaptive behaviour. We propose that this highly specific organization of circuits in the motor system is a core ingredient for supporting behavioural specificity, and at the same time for providing an adequate substrate for behavioural flexibility.
Topics: Basal Ganglia; Brain Stem; Humans; Interneurons; Movement; Neural Pathways; Neurons
PubMed: 35422525
DOI: 10.1038/s41583-022-00581-w -
Cell Jan 2023The cortex influences movement by widespread top-down projections to many nervous system regions. Skilled forelimb movements require brainstem circuitry in the medulla;...
The cortex influences movement by widespread top-down projections to many nervous system regions. Skilled forelimb movements require brainstem circuitry in the medulla; however, the logic of cortical interactions with these neurons remains unexplored. Here, we reveal a fine-grained anatomical and functional map between anterior cortex (AC) and medulla in mice. Distinct cortical regions generate three-dimensional synaptic columns tiling the lateral medulla, topographically matching the dorso-ventral positions of postsynaptic neurons tuned to distinct forelimb action phases. Although medial AC (MAC) terminates ventrally and connects to forelimb-reaching-tuned neurons and its silencing impairs reaching, lateral AC (LAC) influences dorsally positioned neurons tuned to food handling, and its silencing impairs handling. Cortico-medullary neurons also extend collaterals to other subcortical structures through a segregated channel interaction logic. Our findings reveal a precise alignment between cortical location, its function, and specific forelimb-action-tuned medulla neurons, thereby clarifying interaction principles between these two key structures and beyond.
Topics: Mice; Animals; Movement; Neurons; Forelimb; Brain Stem
PubMed: 36608651
DOI: 10.1016/j.cell.2022.12.009 -
Comprehensive Physiology Dec 2023The human sensorimotor control system has exceptional abilities to perform skillful actions. We easily switch between strenuous tasks that involve brute force, such as...
The human sensorimotor control system has exceptional abilities to perform skillful actions. We easily switch between strenuous tasks that involve brute force, such as lifting a heavy sewing machine, and delicate movements such as threading a needle in the same machine. Using a structure with different control architectures, the motor system is capable of updating its ability to perform through our daily interaction with the fluctuating environment. However, there are issues that make this a difficult computational problem for the brain to solve. The brain needs to control a nonlinear, nonstationary neuromuscular system, with redundant and occasionally undesired degrees of freedom, in an uncertain environment using a body in which information transmission is subject to delays and noise. To gain insight into the mechanisms of motor control, here we survey movement laws and invariances that shape our everyday motion. We then examine the major solutions to each of these problems in the three parts of the sensorimotor control system, sensing, planning, and acting. We focus on how the sensory system, the control architectures, and the structure and operation of the muscles serve as complementary mechanisms to overcome deviations and disturbances to motor behavior and give rise to skillful motor performance. We conclude with possible future research directions based on suggested links between the operation of the sensorimotor system across the movement stages. © 2024 American Physiological Society. Compr Physiol 14:5179-5224, 2024.
Topics: Humans; Brain; Movement
PubMed: 38158372
DOI: 10.1002/cphy.c220032 -
The Veterinary Clinics of North... Aug 2022Movement disorders are defined as involuntary movements that are not due to a painful stimulus or associated with changes in consciousness or proprioception. Diagnosis... (Review)
Review
Movement disorders are defined as involuntary movements that are not due to a painful stimulus or associated with changes in consciousness or proprioception. Diagnosis involves ruling out any lameness and neurologic disease and characterizing the gait during walking backward and forward and trotting. Shivers causes abnormal hindlimb hypertonicity during walking backward and, when advanced, a few strides walking forward. Stringhalt causes consistent hyperflexion during walking forward and trotting and variable difficulty when walking backward. Classification and potential causes are discussed as well as other enigmatic movement disorders in horses are presented. Cerebellar abiotrophy is reviewed.
Topics: Animals; Gait; Horse Diseases; Horses; Lameness, Animal; Movement; Movement Disorders
PubMed: 35811199
DOI: 10.1016/j.cveq.2022.05.009 -
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 -
Journal of Plant Research Jan 2021Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in... (Review)
Review
Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in animals relies on the contraction machinery of muscles, many plant movements use turgor pressure as the primary driving force together with secondarily generated elastic forces. The movement of stomata is the best-characterized model system for studying turgor-driven movement, and many gene products responsible for this movement, especially those related to ion transport, have been identified. Similar gene products were recently shown to function in the daily sleep movements of pulvini, the motor organs for macroscopic leaf movements. However, it is difficult to explain the mechanisms behind rapid multicellular movements as a simple extension of the mechanisms used for unicellular or slow movements. For example, water transport through plant tissues imposes a limit on the speed of plant movements, which becomes more severe as the size of the moving part increases. Rapidly moving traps in carnivorous plants overcome this limitation with the aid of the mechanical behaviors of their three-dimensional structures. In addition to a mechanism for rapid deformation, rapid multicellular movements also require a molecular system for rapid cell-cell communication, along with a mechanosensing system that initiates the response. Electrical activities similar to animal action potentials are found in many plant species, representing promising candidates for the rapid cell-cell signaling behind rapid movements, but the molecular entities of these electrical signals remain obscure. Here we review the current understanding of rapid plant movements with the aim of encouraging further biological studies into this fascinating, challenging topic.
Topics: Animals; Models, Biological; Movement; Plant Leaves; Plants
PubMed: 33415544
DOI: 10.1007/s10265-020-01243-7 -
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 -
Advances in Experimental Medicine and... 2022Body language is a powerful form of non-verbal communication providing important information about the emotions and intentions of others. The ability to infer other's... (Review)
Review
Body language is a powerful form of non-verbal communication providing important information about the emotions and intentions of others. The ability to infer other's emotions from their bodily movements and postures recruits an extended network in the brain that encompasses both cortical and subcortical regions. In this chapter, we review recent evidence suggesting that the cerebellum is a critical node of this network. Specifically, we present convergent findings from patients', neuroimaging and non-invasive brain stimulation studies that have shown that the cerebellum is involved in both biological motion perception and in discrimination of bodily emotional expressions. We discuss the potential underlying mechanisms that drive the recruitment of the sensorimotor (anterior) and cognitive (posterior) cerebellum in inferring others' emotions through their bodily movements and postures and how the cerebellum may exert these functions within different cortico-cerebellar and limbic-cerebellar networks dedicated to body language perception.
Topics: Cerebellum; Emotions; Humans; Kinesics; Movement; Perception
PubMed: 35902470
DOI: 10.1007/978-3-030-99550-8_10 -
Integrative and Comparative Biology Dec 2023Motility is an essential factor for an organism's survival and diversification. With the advent of novel single-cell technologies, analytical frameworks, and theoretical... (Review)
Review
Motility is an essential factor for an organism's survival and diversification. With the advent of novel single-cell technologies, analytical frameworks, and theoretical methods, we can begin to probe the complex lives of microscopic motile organisms and answer the intertwining biological and physical questions of how these diverse lifeforms navigate their surroundings. Herein, we summarize the main mechanisms of microscale motility and give an overview of different experimental, analytical, and mathematical methods used to study them across different scales encompassing the molecular-, individual-, to population-level. We identify transferable techniques, pressing challenges, and future directions in the field. This review can serve as a starting point for researchers who are interested in exploring and quantifying the movements of organisms in the microscale world.
Topics: Animals; Movement; Single-Cell Analysis; Models, Theoretical; Cell Movement; Bacteria
PubMed: 37336589
DOI: 10.1093/icb/icad075 -
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