Journal ArticleDOI
Signal-dependent noise determines motor planning
Chris Harris,Daniel M. Wolpert +1 more
TLDR
This theory provides a simple and powerful unifying perspective for both eye and arm movement control and accurately predicts the trajectories of both saccades and arm movements and the speed–accuracy trade-off described by Fitt's law.Abstract:
When we make saccadic eye movements or goal-directed arm movements, there is an infinite number of possible trajectories that the eye or arm could take to reach the target1,2. However, humans show highly stereotyped trajectories in which velocity profiles of both the eye and hand are smooth and symmetric for brief movements3,4. Here we present a unifying theory of eye and arm movements based on the single physiological assumption that the neural control signals are corrupted by noise whose variance increases with the size of the control signal. We propose that in the presence of such signal-dependent noise, the shape of a trajectory is selected to minimize the variance of the final eye or arm position. This minimum-variance theory accurately predicts the trajectories of both saccades and arm movements and the speed–accuracy trade-off described by Fitt's law5. These profiles are robust to changes in the dynamics of the eye or arm, as found empirically6,7. Moreover, the relation between path curvature and hand velocity during drawing movements reproduces the empirical ‘two-thirds power law’8,9. This theory provides a simple and powerful unifying perspective for both eye and arm movement control.read more
Citations
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Journal ArticleDOI
Task-oriented control of muscle coordination during cycling.
TL;DR: Structured aspects of variability were found in the muscle activation of lower leg muscles during cycling that might be interpreted as a transition into a regime that requires specific necessary muscles where the increased constraints of the task specify the muscle coordination pattern in a more precise way.
Journal ArticleDOI
When 90% of the variance is not enough: residual EMG from muscle synergy extraction influences task performance
TL;DR: The study indicates the need for cautious interpretations of results derived from synergy extraction techniques based on heuristics with lenient accuracy levels, and hypothesizes that the residual activity is not entirely random and can influence the execution of motor tasks.
Proceedings ArticleDOI
Perturbation-based measurement of real and imaginary parts of human arm's mechanical impedance
TL;DR: Simulations reveal how spring, mass, and damper contribute to the mechanical impedance and shows that damping which is the real part of impedance is not frequency independent and imaginary part of mechanical impedance decreased with increasing frequency that in turn suggests the stiffness is increasing.
Journal ArticleDOI
Learning with Slight Forgetting Optimizes Sensorimotor Transformation in Redundant Motor Systems
Masaya Hirashima,Daichi Nozaki +1 more
TL;DR: Whether trial-by-trial error-feedback learning with slight forgetting could minimize the motor effort and error in a highly redundant neural network for sensorimotor transformation and whether it could predict the stereotypical activation patterns observed in primary motor cortex (M1) neurons are examined.
Journal ArticleDOI
Step-to-step variations in human running reveal how humans run without falling.
TL;DR: This work implements human-derived control strategies on a simple computational biped, showing that it runs stably for hundreds of steps despite incessant noise-like perturbations or larger discrete perturbation.
References
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Journal ArticleDOI
The information capacity of the human motor system in controlling the amplitude of movement.
TL;DR: The motor system in the present case is defined as including the visual and proprioceptive feedback loops that permit S to monitor his own activity, and the information capacity of the motor system is specified by its ability to produce consistently one class of movement from among several alternative movement classes.
Journal ArticleDOI
The coordination of arm movements: an experimentally confirmed mathematical model.
Tamar Flash,Neville Hogan +1 more
TL;DR: A mathematical model is formulated which is shown to predict both the qualitative features and the quantitative details observed experimentally in planar, multijoint arm movements, and is successful only when formulated in terms of the motion of the hand in extracorporal space.
Journal ArticleDOI
An Internal Model for Sensorimotor Integration
TL;DR: A sensorimotor integration task was investigated in which participants estimated the location of one of their hands at the end of movements made in the dark and under externally imposed forces, providing direct support for the existence of an internal model.
Journal ArticleDOI
Adaptive representation of dynamics during learning of a motor task
TL;DR: The investigation of how the CNS learns to control movements in different dynamical conditions, and how this learned behavior is represented, suggests that the elements of the adaptive process represent dynamics of a motor task in terms of the intrinsic coordinate system of the sensors and actuators.
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Optimal feedback control as a theory of motor coordination.
The coordination of arm movements: an experimentally confirmed mathematical model.
Tamar Flash,Neville Hogan +1 more