scholarly journals Generalization of unconstrained reaching with hand-weight changes

2013 ◽  
Vol 109 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Xiang Yan ◽  
Qining Wang ◽  
Zhengchuan Lu ◽  
Ian H. Stevenson ◽  
Konrad Körding ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Neural Control ◽  
Daily Life ◽  
Weight Changes ◽  
Reaching Task ◽  
The Central Nervous System ◽  
Block Based ◽  
Prior Influence ◽  
Neural Control Of Movement ◽  
Unimodal Pattern

Studies of motor generalization usually perturb hand reaches by distorting visual feedback with virtual reality or by applying forces with a robotic manipulandum. Whereas such perturbations are useful for studying how the central nervous system adapts and generalizes to novel dynamics, they are rarely encountered in daily life. The most common perturbations that we experience are changes in the weights of objects that we hold. Here, we use a center-out, free-reaching task, in which we can manipulate the weight of a participant's hand to examine adaptation and generalization following naturalistic perturbations. In both trial-by-trial paradigms and block-based paradigms, we find that learning converges rapidly (on a timescale of approximately two trials), and this learning generalizes mostly to movements in nearby directions with a unimodal pattern. However, contrary to studies using more artificial perturbations, we find that the generalization has a strong global component. Furthermore, the generalization is enhanced with repeated exposure of the same perturbation. These results suggest that the familiarity of a perturbation is a major factor in movement generalization and that several theories of the neural control of movement, based on perturbations applied by robots or in virtual reality, may need to be extended by incorporating prior influence that is characterized by the familiarity of the perturbation.

scholarly journals Biomechanics as a window into the neural control of movement

2016 ◽  
Vol 52 (1) ◽  
pp. 7-20 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Motor Control ◽  
Neural Control ◽  
Laws Of Nature ◽  
Motor Program ◽  
Uncontrolled Manifold ◽  
Living Systems ◽  
Motor Synergies ◽  
The Central Nervous System ◽  
Definition Of ◽  
Neural Control Of Movement

Abstract Biomechanics and motor control are discussed as parts of a more general science, physics of living systems. Major problems of biomechanics deal with exact definition of variables and their experimental measurement. In motor control, major problems are associated with formulating currently unknown laws of nature specific for movements by biological objects. Mechanics-based hypotheses in motor control, such as those originating from notions of a generalized motor program and internal models, are non-physical. The famous problem of motor redundancy is wrongly formulated; it has to be replaced by the principle of abundance, which does not pose computational problems for the central nervous system. Biomechanical methods play a central role in motor control studies. This is illustrated with studies with the reconstruction of hypothetical control variables and those exploring motor synergies within the framework of the uncontrolled manifold hypothesis. Biomechanics and motor control have to merge into physics of living systems, and the earlier this process starts the better.

scholarly journals Virtual Reality Augmented Feedback Rehabilitation Associated to Action Observation Therapy in Buccofacial Apraxia: Case Report

2021 ◽  
Vol 14 ◽  
pp. 117954762199457
Author(s):  
Daniele Emedoli ◽  
Maddalena Arosio ◽  
Andrea Tettamanti ◽  
Sandro Iannaccone
Keyword(s):  
Virtual Reality ◽  
Neural Plasticity ◽  
Action Observation ◽  
Voluntary Movements ◽  
Augmented Feedback ◽  
Lower Face ◽  
Facial Movements ◽  
Upper Face ◽  
The Central Nervous System ◽  
Buccofacial Apraxia

Background: Buccofacial Apraxia is defined as the inability to perform voluntary movements of the larynx, pharynx, mandible, tongue, lips and cheeks, while automatic or reflexive control of these structures is preserved. Buccofacial Apraxia frequently co-occurs with aphasia and apraxia of speech and it has been reported as almost exclusively resulting from a lesion of the left hemisphere. Recent studies have demonstrated the benefit of treating apraxia using motor training principles such as Augmented Feedback or Action Observation Therapy. In light of this, the study describes the treatment based on immersive Action Observation Therapy and Virtual Reality Augmented Feedback in a case of Buccofacial Apraxia. Participant and Methods: The participant is a right-handed 58-years-old male. He underwent a neurosurgery intervention of craniotomy and exeresis of infra axial expansive lesion in the frontoparietal convexity compatible with an atypical meningioma. Buccofacial Apraxia was diagnosed by a neurologist and evaluated by the Upper and Lower Face Apraxia Test. Buccofacial Apraxia was quantified also by a specific camera, with an appropriately developed software, able to detect the range of motion of automatic face movements and the range of the same movements on voluntary requests. In order to improve voluntary movements, the participant completed fifteen 1-hour rehabilitation sessions, composed of a 20-minutes immersive Action Observation Therapy followed by a 40-minutes Virtual Reality Augmented Feedback sessions, 5 days a week, for 3 consecutive weeks. Results: After treatment, participant achieved great improvements in quality and range of facial movements, performing most of the facial expressions (eg, kiss, smile, lateral angle of mouth displacement) without unsolicited movement. Furthermore, the Upper and Lower Face Apraxia Test showed an improvement of 118% for the Upper Face movements and of 200% for the Lower Face movements. Conclusion: Performing voluntary movement in a Virtual Reality environment with Augmented Feedbacks, in addition to Action Observation Therapy, improved performances of facial gestures and consolidate the activations by the central nervous system based on principles of experience-dependent neural plasticity.

Efference copy in kinesthetic perception: A copy of what is it?

2021 ◽  
Author(s):  
Mark L. Latash
Keyword(s):  
Neural Control ◽  
Efference Copy ◽  
Single Element ◽  
Muscle Vibration ◽  
Sense Of Effort ◽  
Antagonist Muscles ◽  
Co Activation ◽  
Lower Accuracy ◽  
Neural Control Of Movement ◽  
Kinesthetic Perception

A number of notions in the fields of motor control and kinesthetic perception have been used without clear definitions. In this review, we consider definitions for efference copy, percept, and sense of effort based on recent studies within the physical approach, which assumes that the neural control of movement is based on principles of parametric control and involves defining time-varying profiles of spatial referent coordinates for the effectors. The apparent redundancy in both motor and perceptual processes is reconsidered based on the principle of abundance. Abundance of efferent and afferent signals is viewed as the means of stabilizing both salient action characteristics and salient percepts formalized as stable manifolds in high-dimensional spaces of relevant elemental variables. This theoretical scheme has led recently to a number of novel predictions and findings. These include, in particular, lower accuracy in perception of variables produced by elements involved in a multi-element task compared to the same elements in single-element tasks, dissociation between motor and perceptual effects of muscle co-activation, force illusions induced by muscle vibration, and errors in perception of unintentional drifts in performance. Taken together, these results suggest that participation of efferent signals in perception frequently involves distorted copies of actual neural commands, particularly those to antagonist muscles. Sense of effort is associated with such distorted efferent signals. Distortions in efference copy happen spontaneously and can also be caused by changes in sensory signals, e.g., those produced by muscle vibration.

scholarly journals Muscle activation patterns are more constrained and regular in treadmill than in overground human locomotion

2020 ◽  
Author(s):  
Ilaria Mileti ◽  
Aurora Serra ◽  
Nerses Wolf ◽  
Victor Munoz-Martel ◽  
Antonis Ekizos ◽  
...  
Keyword(s):  
Neural Control ◽  
Muscle Activation ◽  
Human Locomotion ◽  
Activation Patterns ◽  
Motor Primitives ◽  
Muscle Activation Patterns ◽  
Synergistic Activation ◽  
Clinical Environments ◽  
The Central Nervous System ◽  
Main Activity

AbstractThe use of motorized treadmills as convenient tools for the study of locomotion has been in vogue for many decades. However, despite the widespread presence of these devices in many scientific and clinical environments, a full consensus on their validity to faithfully substitute free overground locomotion is still missing. Specifically, little information is available on whether and how the neural control of movement is affected when humans walk and run on a treadmill as compared to overground. Here, we made use of linear and nonlinear analysis tools to extract information from electromyographic recordings during walking and running overground, and on an instrumented treadmill. We extracted synergistic activation patterns from the muscles of the lower limb via non-negative matrix factorization. We then investigated how the motor modules (or time-invariant muscle weightings) were used in the two locomotion environments. Subsequently, we examined the timing of motor primitives (or time-dependent coefficients of muscle synergies) by calculating their duration, the time of main activation, and their Hurst exponent, a nonlinear metric derived from fractal analysis. We found that motor modules were not influenced by the locomotion environment, while motor primitives resulted overall more regular in treadmill than in overground locomotion, with the main activity of the primitive for propulsion shifted earlier in time. Our results suggest that the spatial and sensory constraints imposed by the treadmill environment forced the central nervous system to adopt a different neural control strategy than that used for free overground locomotion. A data-driven indication that treadmills induce perturbations to the neural control of locomotion.

scholarly journals The impact of experimental pain on shoulder movement during an arm elevated reaching task in a virtual reality environment

2021 ◽  
Vol 9 (18) ◽  
Author(s):  
Frédérique Dupuis ◽  
Gisela Sole ◽  
Craig A. Wassinger ◽  
Hamish Osborne ◽  
Mathieu Beilmann ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Experimental Pain ◽  
Virtual Reality Environment ◽  
Reaching Task ◽  
Shoulder Movement ◽  
The Impact

scholarly journals On The Hormonal and Neural Control of the Release of Gametes in Ascidians

1951 ◽  
Vol 28 (4) ◽  
pp. 463-472
Author(s):  
D. B. CARLISLE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neural Control ◽  
Sense Organ ◽  
Chorionic Gonadotrophin ◽  
Gamete Release ◽  
The Central Nervous System ◽  
Neural Region

1. It is argued that the neural gland (+ciliated pit) of ascidians is homologous with the entire pituitary of vertebrates, adenohypophysis as well as neurohypophysis. 2. Ciona and Phallusia are shown to respond to an injection of chorionic gonadotrophin by the release of gametes. 3. They respond in the same way to feeding with eggs and sperm of their own species but not to those of other species. 4. This response is prevented in both cases by section of the nerves from the ganglion to the region of the gonads. 5. Destruction of the heart and removal of the blood does not prevent the response to feeding with gametes, nor to injection of gonadotrophin into the neural region; this operation does prevent the reaction if the site of injection is elsewhere. 6. Destruction of the neural gland, leaving the ganglion intact, prevents the response to feeding with gametes, but does not prevent its following an injection of chorionic gonadotrophin. 7. The hypothesis is advanced that the neural gland (+ciliated pit) is the sense organ involved in this response to feeding, and that it produces gonadotrophin and passes it to the ganglion by a non-vascular route; the ganglion then stimulates by nervous pathways the gonads to release gametes. 8. It is suggested that gonadotrophin is here fulfilling a sensory role in passing information from sense organ to the central nervous system. It may be contrasted with adrenalin which passes instructions from the central nervous system to effectors. 9. Phallusia is shown to respond with gamete release to an injection of an extract of the neural complex of Ciona.

Phygital Customer Experience Mixed Approach of Augmented Reality and Customer Experience (DCX) in the Context of Heritage Tourism

2021 ◽  
pp. 238-253
Author(s):  
Nedra Bahri Ammari ◽  
Ines El Hassoumi
Keyword(s):  
Virtual Reality ◽  
Augmented Reality ◽  
Daily Life ◽  
Heritage Tourism ◽  
Customer Experience ◽  
Modern Technology ◽  
Digital Transformation ◽  
Heritage Sites ◽  
Primary Driver ◽  
Mixed Approach

What if customer experience was the primary driver of digital transformation? Indeed, new hybrid experiences have emerged thanks to daily-life technologies that fused both digital and physical worlds. This kind of experience uses applications and connected objects (IoT) to adapt and respond to consumer needs. Augmented reality and virtual reality are one of the most functionally and emotionally memorable phygital experiences that create value for customers. In this chapter, the authors chose heritage tourism as the study field for different reasons. While the adoption of augmented and virtual reality is gaining grownd, cultural heritage sites have started to consider the possibilities offered by these new and innovative technologies. This industry is starting to integrate AR and VR in several ways to attract more people. However, it is necessary to study how modern technology can be developed and implemented in a meaningful way to improve the tourist's experience. An AR- and VR-based mobile application has been developed and tested at Antonine's Baths in Carthage, Tunisia.

Health in a connected world

2020 ◽  
pp. 573-580
Author(s):  
Philippe Delespaul ◽  
Catherine van Zelst
Keyword(s):  
Mental Health ◽  
Virtual Reality ◽  
Lived Experience ◽  
Therapeutic Relationship ◽  
Social Relationships ◽  
Daily Life ◽  
Mental Healthcare ◽  
Well Being ◽  
Service Users ◽  
Changing World

This chapter is about a redesign of mental healthcare, as it evolves in a changing world. It focuses on digital transformations and their impact on social relationships, networks, and communities. It intends to demonstrate better responses to the needs of service users in society. It first defines terminologies to access the changing world and focus on how to understand health, recovery, and well-being in people with lived experience of psychosis. These central elements can be accessed or maintained using eHealth, including mHealth, virtual reality, and eCommunities. It also discuss strengths, challenges, and pitfalls in developing and applying innovative interventions in the context of daily life. It reviews these trends and how these relate to the therapeutic relationship in general, and the mental health practitioner’s role in particular.

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