: This thesis applies neural network feature selection techniques to multivariate time series data to improve prediction of a target time series. Two approaches to feature selection are used. First, a subset enumeration method is used to determine which financial indicators are most useful for aiding in prediction of the S&P 500 futures daily price. The candidate indicators evaluated include RSI, Stochastics and several moving averages. Results indicate that the Stochastics and RSI indicators result in better prediction results than the moving averages. The second approach to feature selection is calculation of individual saliency metrics. A new decision boundary-based individual saliency metric, and a classifier independent saliency metric are developed and tested. Ruck's saliency metric, the decision boundary based saliency metric, and the classifier independent saliency metric are compared for a data set consisting of the RSI and Stochastics indicators as well as delayed closing price values. The decision based metric and the Ruck metric results are similar, but the classifier independent metric agrees with neither of the other metrics. The nine most salient features, determined by the decision boundary based metric, are used to train a neural network and the results are presented and compared to other published results. (AN)

/pdf/nonlinear-time-series-analysis-1j3a35n4y3.pdf

Nonlinear Time Series Analysis.

The exploits of Martina Navratilova and Roger Federer represent the pinnacle of motor learning. However, when considering the range and complexity of the processes that are involved in motor learning, even the mere mortals among us exhibit abilities that are impressive. We exercise these abilities when taking up new activities — whether it is snowboarding or ballroom dancing — but also engage in substantial motor learning on a daily basis as we adapt to changes in our environment, manipulate new objects and refine existing skills. Here we review recent research in human motor learning with an emphasis on the computational mechanisms that are involved.

/pdf/principles-of-sensorimotor-learning-59h00bcrss.pdf

Principles of sensorimotor learning.

Fundamental Statistics in Psychology and Education

http://blam-lab.org/publications/pdf/Papers/11KrakauerMazzoniCOinNB.pdf

Human sensorimotor learning: adaptation, skill, and beyond

http://blam-lab.org/publications/pdf/Papers/Huang-et-al-Neuron-2011.pdf

Rethinking motor learning and savings in adaptation paradigms: model-free memory for successful actions combines with internal models.

Human motor behavior is constantly adapted through the process of error-based learning. When the motor system encounters an error, its estimate about the body and environment will change, and the next movement will be immediately modified to counteract the underlying perturbation. Here, we show that a second mechanism, use-dependent learning, simultaneously changes movements to become more similar to the last movement. In three experiments, participants made reaching movements toward a horizontally elongated target, such that errors in the initial movement direction did not have to be corrected. Along this task-redundant dimension, we were able to induce use-dependent learning by passively guiding movements in a direction angled by 8 degrees from the previous direction. In a second study, we show that error-based and use-dependent learning can change motor behavior simultaneously in opposing directions by physically constraining the direction of active movements. After removal of the constraint, participants briefly exhibit an error-based aftereffect against the direction of the constraint, followed by a longer-lasting use-dependent aftereffect in the direction of the constraint. In the third experiment, we show that these two learning mechanisms together determine the solution the motor system adopts when learning a motor task.

https://www.jneurosci.org/content/jneuro/30/15/5159.full.pdf

Use-Dependent and Error-Based Learning of Motor Behaviors

Investigating cyclic vertical arm movements with an instrumented hand-held load in an airplane undergoing parabolic flight profiles allowed us to determine how humans modulate their grip force when the gravitational and the inertial components of the load force are varied independently. Eight subjects participated in this study; four had already experienced parabolic flights and four had not. The subjects were asked to move the load up and down continuously at three different gravitational conditions (1 g, 1.8 g, and 0 g). At 1 g, the grip force precisely anticipated the fluctuations in the load force, which was maximum at the bottom of the object trajectory and minimum at the top. When gravity changed, the temporal coupling between grip force and load force persisted for all subjects from the first parabola. At 0 g, the grip force was accurately adjusted to the two load force peaks occurring at the two opposite extremes of the trajectory due to the absence of weight. While the experienced subjects exerted a grip force appropriate to a new combination of weight and inertia since their first trial, the inexperienced subjects dramatically increased their grip when faced with either high or low force levels for the first time. Then they progressively released their grip until a continuous grip-load force relationship with regard to 1 g was established after the fifth parabola. We suggest that a central representation of the new gravitational field was rapidly acquired through the incoming vestibular and somatic sensory information.

The effects of a change in gravity on the dynamics of prehension

In this experiment we examined the coupling between grip force and load force observed during cyclic vertical arm movements with a hand-held object, performed in different gravitational environments. Six subjects highly experienced in parabolic flight participated in this study. They had to continuously move a cylindrical object up and down in the different gravity fields (1g, 1.8 g and 0 g) induced by parabolic flights. The imposed movement frequency was 1 Hz, the object mass was either 200 or 400 g, the amplitude of movement was either 20 or 40 cm and an additional mass of 200 g could be wound around the forearm. Each subject performed the task during 15 consecutive parabolas. The coordination between the grip force normal to the surface and the tangential load force was examined in nine loading conditions. We observed that the same normal grip force was used for equivalent loads generated by changes of mass, gravity or acceleration despite the fact that these loads required different motor commands to move the arm. Moreover, our results suggest that the gravitational and inertial components of the load are treated adequately and independently by the internal models used to predictively control the required grip force. These results indicate that the forward internal models used to control precision grip take into account the dynamic characteristics of the upper limb, the object and the environment to predict the object's acceleration and, in turn, the load force acting at the fingertips.

/pdf/do-novel-gravitational-environments-alter-the-grip-force-50ca71awov.pdf

Do novel gravitational environments alter the grip-force/load-force coupling at the fingertips?

The THESEUS project (Towards Human Exploration of Space: a
EUropean Strategy) was initiated within the seventh Framework
Programme by the European Commission. This project aimed to
provide a cross-cutting, life science-based roadmap for Europe’s
strategy towards human exploration of space, especially for deep
space missions and its relevance to applications on Earth. To
address these challenges, relevance of space research on the
cardiovascular system, the lungs and kidneys, was discussed in an
expert group and its principal conclusions will be presented in this
article.

https://hal.archives-ouvertes.fr/hal-01488420/document

Olivier White

Papers

Use-Dependent and Error-Based Learning of Motor Behaviors

The effects of a change in gravity on the dynamics of prehension

Do novel gravitational environments alter the grip-force/load-force coupling at the fingertips?

Towards human exploration of space: the THESEUS review series on cardiovascular, respiratory, and renal research priorities

Responsibility assignment in redundant systems.