Retention and interference of learned dexterous manipulation: interaction between multiple sensorimotor processes

2015 ◽  
Vol 113 (1) ◽  
pp. 144-155 ◽  
Author(s):  
Qiushi Fu ◽  
Marco Santello
Keyword(s):  
Human Subjects ◽  
Vertical Axis ◽  
Learning Theories ◽  
Dexterous Manipulation ◽  
Context Sensitive ◽  
Object Rotation ◽  
Sensorimotor Memory ◽  
The Central Nervous System ◽  
Retrieval Interference ◽  
Sensorimotor Mechanisms

An object can be used in multiple contexts, each requiring different hand actions. How the central nervous system builds and maintains memory of such dexterous manipulations remains unclear. We conducted experiments in which human subjects had to learn and recall manipulations performed in two contexts, A and B. Both contexts involved lifting the same L-shaped object whose geometry cued its asymmetrical mass distribution. Correct performance required producing a torque on the vertical handle at object lift onset to prevent it from tilting. The torque direction depended on the context, i.e., object orientation, which was changed by 180° object rotation about a vertical axis. With an A1B1A2 context switching paradigm, subjects learned A1 in the first block of eight trials as indicated by a torque approaching the required one. However, subjects made large errors in anticipating the required torque when switching to B1 immediately after A1 (negative transfer), as well as when they had to recall A1 when switching to A2 after learning B through another block of eight lifts (retrieval interference). Classic sensorimotor learning theories attribute such interferences to multi-rate, multi-state error-driven updates of internal models. However, by systematically changing the interblock break duration and within-block number of trials, our results suggest an alternative explanation underlying interference and retention of dexterous manipulation. Specifically, we identified and quantified through a novel computational model the nonlinear interaction between two sensorimotor mechanisms: a short-lived, context-independent, use-dependent sensorimotor memory and a context-sensitive, error-based learning process.

scholarly journals Manipulation After Object Rotation Reveals Independent Sensorimotor Memory Representations of Digit Positions and Forces

2010 ◽  
Vol 103 (6) ◽  
pp. 2953-2964 ◽  
Author(s):  
Wei Zhang ◽  
Andrew M. Gordon ◽  
Qiushi Fu ◽  
Marco Santello
Keyword(s):  
Center Of Mass ◽  
Vertical Axis ◽  
Visuomotor Transformations ◽  
External Moment ◽  
Object Rotation ◽  
Sensorimotor Memory ◽  
Memory Representations ◽  
Tangential Forces ◽  
Kinematics And Kinetics ◽  
Insight Into

Planning of object manipulations is dependent on the ability to generate, store, and retrieve sensorimotor memories of previous actions associated with grasped objects. However, the sensorimotor memory representations linking object properties to the planning of grasp are not well understood. Here we use an object rotation task to gain insight into the mechanisms underlying the nature of these sensorimotor memories. We asked subjects to grasp a grip device with an asymmetrical center of mass (CM) anywhere on its vertical surfaces and lift it while minimizing object roll. After subjects learned to minimize object roll by generating a compensatory moment, they were asked to rotate the object 180° about a vertical axis and lift it again. The rotation resulted in changing the direction of external moment opposite to that experienced during the prerotation block. Anticipatory grasp control was quantified by measuring the compensatory moment generated at object lift onset by thumb and index finger forces through their respective application points. On the first postrotation trial, subjects failed to generate a compensatory moment to counter the external moment caused by the new CM location, thus resulting in a large object roll. Nevertheless, after several object rotations subjects reduced object roll on the initial postrotation trials by anticipating the new CM location through the modulation of digit placement but not tangential forces. The differential improvement in modulating these two variables supports the notion of independent memory representations of kinematics and kinetics and is discussed in relation to neural mechanisms underlying visuomotor transformations.

The Development of a Human Gait Model With Predictive Capability and the Simulation of Able-Bodied Gait

2015 ◽  
Author(s):  
Jinming Sun ◽  
Shaoli Wu ◽  
Philip A. Voglewede
Keyword(s):  
Control Algorithm ◽  
Human Subjects ◽  
Human Gait ◽  
Control Input ◽  
Trial And Error ◽  
Predictive Capability ◽  
Gait Simulation ◽  
Plant Model ◽  
The Central Nervous System ◽  
The Cost

The development of current prostheses and orthoses typically follows a trial and error approach where the devices are designed based on experience, tried on human subjects and then redesigned iteratively. This design approach is costly, risky and time consuming. A predictive human gait model is desired such that prostheses can be virtually tested so that their performance can be predicted qualitatively, the cost can be reduced, and the risks can be minimized. The development of such a model is explained in this paper. The developed model includes two parts: a plant model which represents the forward dynamics of human gait and a controller which represents the central nervous system (CNS). The development of the plant model is explained in a different paper. This paper focuses on the control algorithm development and able-bodied gait simulation. The controller proposed in this paper utilizes model predictive control (MPC). MPC uses an internal model to predict the output in advance, compare the predicted output to the reference, and optimize control input so that the error between them is minimal. The developed predictive human gait model was validated by simulating able-bodied human gait. The simulation results showed that the controller is able to simulate the kinematic output close to experimental data.

Eye-head coordination during large gaze shifts

1995 ◽  
Vol 73 (2) ◽  
pp. 766-779 ◽  
Author(s):  
D. Tweed ◽  
B. Glenn ◽  
T. Vilis
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Head Movements ◽  
Gaze Shifts ◽  
Healthy Human ◽  
Vertical Movements ◽  
The Gaze ◽  
Acceleration And Deceleration

1. Three-dimensional (3D) eye and head rotations were measured with the use of the magnetic search coil technique in six healthy human subjects as they made large gaze shifts. The aims of this study were 1) to see whether the kinematic rules that constrain eye and head orientations to two degrees of freedom between saccades also hold during movements; 2) to chart the curvature and looping in eye and head trajectories; and 3) to assess whether the timing and paths of eye and head movements are more compatible with a single gaze error command driving both movements, or with two different feedback loops. 2. Static orientations of the eye and head relative to space are known to resemble the distribution that would be generated by a Fick gimbal (a horizontal axis moving on a fixed vertical axis). We show that gaze point trajectories during eye-head gaze shifts fit the Fick gimbal pattern, with horizontal movements following straight "line of latitude" paths and vertical movements curving like lines of longitude. However, horizontal (and to a lesser extent vertical) movements showed direction-dependent looping, with rightward and leftward (and up and down) saccades tracing slightly different paths. Plots of facing direction (the analogue of gaze direction for the head) also showed the latitude/longitude pattern, without looping. In radial saccades, the gaze point initially moved more vertically than the target direction and then curved; head trajectories were straight. 3. The eye and head components of randomly sequenced gaze shifts were not time locked to one another. The head could start moving at any time from slightly before the eye until 200 ms after, and the standard deviation of this interval could be as large as 80 ms. The head continued moving for a long (up to 400 ms) and highly variable time after the gaze error had fallen to zero. For repeated saccades between the same targets, peak eye and head velocities were directly, but very weakly, correlated; fast eye movements could accompany slow head movements and vice versa. Peak head acceleration and deceleration were also very weakly correlated with eye velocity. Further, the head rotated about an essentially fixed axis, with a smooth bell-shaped velocity profile, whereas the axis of eye rotation relative to the head varied throughout the movement and the velocity profiles were more ragged. 4. Plots of 3D eye orientation revealed strong and consistent looping in eye trajectories relative to space.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Electrically Evoked Itch in Human Subjects

2021 ◽  
Vol 7 ◽  
Author(s):  
Hans Jürgen Solinski ◽  
Roman Rukwied
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Human Subjects ◽  
Electrical Activation ◽  
Peripheral Neurons ◽  
The Past ◽  
C Fibers ◽  
Chronic Itch ◽  
Transduction Mechanisms ◽  
The Central Nervous System

Administration of chemicals (pruritogens) into the skin evokes itch based on signal transduction mechanisms that generate action potentials mainly in mechanically sensitive and insensitive primary afferent C-fibers (pruriceptors). These signals from peripheral neurons are processed in spinal and supra-spinal centers of the central nervous system and finally generate the sensation of itch. Compared to chemical stimulation, electrical activation of pruriceptors would allow for better temporal control and thereby a more direct functional assessment of their activation. Here, we review the electrical stimulation paradigms which were used to evoke itch in humans in the past. We further evaluate recent attempts to explore electrically induced itch in atopic dermatitis patients. Possible mechanisms underlying successful pruritus generation in chronic itch patients by transdermal slowly depolarizing electrical stimulation are discussed.

scholarly journals Neuropathology and Virus in Brain of SARS-CoV-2 Infected Non-Human Primates

2020 ◽  
Author(s):  
Tracy Fischer ◽  
Ibolya Rutkai ◽  
Meredith Mayer ◽  
Linh Hellmers ◽  
Bo Ning ◽  
...  
Keyword(s):  
Human Subjects ◽  
Severe Disease ◽  
Etiologic Agent ◽  
Cns Injury ◽  
Hypoxic Injury ◽  
Appropriate Treatment ◽  
Relevant Animal Model ◽  
The Central Nervous System ◽  
Infection Disease ◽  
First Time

Abstract Neurological manifestations are a significant complication of coronavirus infection disease-19 (COVID-19). Understanding how COVID-19 contributes to neurological disease is needed for appropriate treatment of infected patients, as well as in initiating relevant follow-up care after recovery. Investigation of autopsied brain tissue has been key to advancing our understanding of the neuropathogenesis of a large number of infectious and non-infectious diseases affecting the central nervous system (CNS). Due to the highly infectious nature of the etiologic agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a paucity of tissues available for comprehensive investigation. Here, we show for the first time, microhemorrhages and neuropathology that is consistent with hypoxic injury in SARS-CoV-2 infected non-human primates (NHPs). Importantly, this was seen among infected animals that did not develop severe respiratory disease. This finding underscores the importance of vaccinating against SARS-CoV-2, even among populations that have a reduced risk for developing of severe disease, to prevent long-term or permanent neurological sequelae. Sparse virus was detected in brain endothelial cells but did not associate with the severity of CNS injury. We anticipate our findings will advance our current understanding of the neuropathogenesis of SARS-CoV-2 infection and demonstrate SARS-CoV-2 infected NHPs are a highly relevant animal model for investigating COVID-19 neuropathogenesis among human subjects.

scholarly journals Ngly1 −/− rats develop neurodegenerative phenotypes and pathological abnormalities in their peripheral and central nervous systems

2020 ◽  
Vol 29 (10) ◽  
pp. 1635-1647 ◽  
Author(s):  
Makoto Asahina ◽  
Reiko Fujinawa ◽  
Sayuri Nakamura ◽  
Kotaro Yokoyama ◽  
Ryuichi Tozawa ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Human Subjects ◽  
Significant Loss ◽  
Ubiquitinated Proteins ◽  
Central Nervous Systems ◽  
Mature Neurons ◽  
The Central Nervous System ◽  
Axonal Degradation ◽  
Lateral Nucleus ◽  
Disability Movement

Abstract N-glycanase 1 (NGLY1) deficiency, an autosomal recessive disease caused by mutations in the NGLY1 gene, is characterized by developmental delay, hypolacrima or alacrima, seizure, intellectual disability, movement disorders and other neurological phenotypes. Because of few animal models that recapitulate these clinical signatures, the mechanisms of the onset of the disease and its progression are poorly understood, and the development of therapies is hindered. In this study, we generated the systemic Ngly1-deficient rodent model, Ngly1−/− rats, which showed developmental delay, movement disorder, somatosensory impairment and scoliosis. These phenotypes in Ngly1−/− rats are consistent with symptoms in human patients. In accordance with the pivotal role played by NGLY1 in endoplasmic reticulum-associated degradation processes, cleaving N-glycans from misfolded glycoproteins in the cytosol before they can be degraded by the proteasome, loss of Ngly1 led to accumulation of cytoplasmic ubiquitinated proteins, a marker of misfolded proteins in the neurons of the central nervous system of Ngly1−/− rats. Histological analysis identified prominent pathological abnormalities, including necrotic lesions, mineralization, intra- and extracellular eosinophilic bodies, astrogliosis, microgliosis and significant loss of mature neurons in the thalamic lateral and the medial parts of the ventral posterior nucleus and ventral lateral nucleus of Ngly1−/− rats. Axonal degradation in the sciatic nerves was also observed, as in human subjects. Ngly1−/− rats, which mimic the symptoms of human patients, will be a useful animal model for preclinical testing of therapeutic options and understanding the detailed mechanisms of NGLY1 deficiency.

Characteristics of secondary phase post-rotatory nystagmus following off-vertical axis rotation in humans

2000 ◽  
Vol 10 (3) ◽  
pp. 143-150
Author(s):  
Joseph M. Furman ◽  
Izumi Koizuka ◽  
Robert H. Schor
Keyword(s):  
Slow Component ◽  
Human Subjects ◽  
Secondary Phase ◽  
Vertical Axis ◽  
Lateral Position ◽  
Search Coil ◽  
Temporal Properties ◽  
Normal Human ◽  
Axis Rotation ◽  
A Minor

The nystagmus following yaw earth-vertical axis rotation often reverses direction, a phenomenon known as the “secondary phase”. The purpose of this study was to examine the existence and the spatial and temporal properties of the secondary phase of post-rotatory nystagmus following off-vertical axis rotation (OVAR). Eleven normal human subjects were rotated at 120 or 180 ∘ /s about an off-vertical axis and stopped in the left ear down or right ear down lateral position. Horizontal and vertical eye positions were recorded with a scleral search coil, and horizontal and vertical slow component eye velocities were computed. Our results indicate that (a) there is a robust secondary phase nystagmus following OVAR, and (b) the direction of the secondary phase nystagmus tends to align with earth-horizontal. These results can be explained by a minor modification of an existing VOR model that has been shown to produce secondary phase responses.

Influence of rotational inertia on turning performance of theropod dinosaurs: clues from humans with increased rotational inertia

2001 ◽  
Vol 204 (22) ◽  
pp. 3917-3926
Author(s):  
David R. Carrier ◽  
Rebecca M. Walter ◽  
David V. Lee
Keyword(s):  
Average Velocity ◽  
Human Subjects ◽  
Tail Length ◽  
Vertical Axis ◽  
The Body ◽  
Rotational Inertia ◽  
Control Value ◽  
Theropod Dinosaurs ◽  
Axis Of Rotation ◽  
Average Angle

SUMMARY The turning agility of theropod dinosaurs may have been severely limited by the large rotational inertia of their horizontal trunks and tails. Bodies with mass distributed far from the axis of rotation have much greater rotational inertia than bodies with the same mass distributed close to the axis of rotation. In this study, we increased the rotational inertia about the vertical axis of human subjects 9.2-fold, to match our estimate for theropods the size of humans, and measured the ability of the subjects to turn. To determine the effect of the increased rotational inertia on maximum turning capability, five subjects jumped vertically while attempting to rotate as far as possible about their vertical axis. This test resulted in a decrease in the average angle turned to 20 % of the control value. We also tested the ability of nine subjects to run as rapidly as possible through a tight slalom course of six 90° turns. When the subjects ran with the 9.2-fold greater rotational inertia, the average velocity through the course decreased to 77 % of the control velocity. When the subjects ran the same course but were constrained as to where they placed their feet, the average velocity through the course decreased to 65 % of the control velocity. These results are consistent with the hypothesis that rotational inertia may have limited the turning performance of theropods. They also indicate that the effect of rotational inertia on turning performance is dependent on the type of turning behavior. Characters such as retroverted pubes, reduced tail length, decreased body size, pneumatic vertebrae and the absence of teeth reduced rotational inertia in derived theropods and probably, therefore, improved their turning agility. To reduce rotational inertia, theropods may have run with an arched back and tail, an S-curved neck and forelimbs held backwards against the body.

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