The next move in neuromodulation therapy: a question of timing.

International audienc

Using a virtual cortical module implementing a neural field model to modulate brain rhythms in Parkinson’s disease

We propose a new method for selective modulation of cortical rhythms based on neural field theory, in which the activity of a cortical area is extensively monitored using a two-dimensional microelectrode array. The example of Parkinson’s disease illustrates the proposed method, in which a neural field model is assumed to accurately describe experimentally recorded activity. In addition, we propose a new closed-loop stimulation signal that is both space- and time- dependent. This method is especially designed to specifically modulate a targeted brain rhythm, without interfering with other rhythms. A new class of neuroprosthetic devices is also proposed, in which the multielectrode array is seen as an artificial neural network interacting with biological tissue. Such a bio-inspired approach may provide a solution to optimize interactions between the stimulation device and the cortex aiming to attenuate or augment specific cortical rhythms. The next step will be to validate this new approach experimentally in patients with Parkinson’s disease

Complex Motor Dynamics and Control in Multi-looped Negative Feedback Systems

Experiments were performed in normal and Parkinsonian subjects who were asked to maintain a constant finger position using time-delayed visual feedback. The finger position showed complex dynamics, with characteristic differences between normal and Parkinosonian subjects. Here we discuss some of the theoretical issues that must be resolved in order to understand the mechanisms that underlie the generation of these complex signals

Nonlinear dynamics in physiology and medicine /

This book deals with the application of mathematics in modeling and understanding physiological systems, especially those involving rhythms. It is divided roughly into two sections. In the first part of the book, the authors introduce ideas and techniques from nonlinear dynamics that are relevant to the analysis of biological rhythms. The second part consists of five in-depth case studies in which the authors use the theoretical tools developed earlier to investigate a number of physiological processes: the dynamics of excitable nerve and cardiac tissue, resetting and entrainment of biological oscillators, the effects of noise and time delay on the pupil light reflex, pathologies associated with blood cell replication, and Parkinsonian tremor. One novel feature of the book is the inclusion of classroom-tested computer exercises throughout, designed to form a bridge between the mathematical theory and physiological experiments. This book will be of interest to students and researchers in the natural and physical sciences wanting to learn about the complexities and subtleties of physiological systems from a mathematical perspective. The authors are members of the Centre for Nonlinear Dynamics in Physiology and Medicine. The material in this book was developed for use in courses and was presented in three Summer Schools run by the authors in Montreal.Includes bibliographical references (p. [385]-426) and index.This book deals with the application of mathematics in modeling and understanding physiological systems, especially those involving rhythms. It is divided roughly into two sections. In the first part of the book, the authors introduce ideas and techniques from nonlinear dynamics that are relevant to the analysis of biological rhythms. The second part consists of five in-depth case studies in which the authors use the theoretical tools developed earlier to investigate a number of physiological processes: the dynamics of excitable nerve and cardiac tissue, resetting and entrainment of biological oscillators, the effects of noise and time delay on the pupil light reflex, pathologies associated with blood cell replication, and Parkinsonian tremor. One novel feature of the book is the inclusion of classroom-tested computer exercises throughout, designed to form a bridge between the mathematical theory and physiological experiments. This book will be of interest to students and researchers in the natural and physical sciences wanting to learn about the complexities and subtleties of physiological systems from a mathematical perspective. The authors are members of the Centre for Nonlinear Dynamics in Physiology and Medicine. The material in this book was developed for use in courses and was presented in three Summer Schools run by the authors in Montreal

Activation automatique et contrôlée de la mémoire sémantique (amorçage associatif vs catégoriel en champ visuel divisé et potentiels cognitifs)

BORDEAUX2-BU Sci.Homme/Odontol. (330632102) / SudocSudocFranceF

Effets d'un champ magnétique d'extrêmement basse fréquence sur les micro-mouvements segmentaires humains

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU STAPS (341722109) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Analysis of phase waves in the ECoG data

Subdural ECoG data recorded from the matrix of electrodes during syllable pronunciation are analyzed by the method of circular-linear regression. Phase waves in 1D electrode arrays and in the whole 2D set of electrodes are detected, and their spatial organization and temporal evolution are studied. Phase portraits of wave vectors indicate the presence of sources, sinks, and saddle points. The analysis of temporal evolution of phase portraits shows that they changed more at the beginning of syllable pronunciation. Furthermore, wave sources were more stable in their localization during the pronunciation. Overall, in spite of large variability of phase portraits, they represent some characterization of the dynamics of electric potential in the cerebral cortex

Analysis of the Arousal Motor-Performance Relationship in Children Using Movement Kinematics

The purpose of this interdisciplinary study was to assess the impact of arousal on motor performance by examining the kinematic characteristics of a stepping motion in high and low arousal conditions on 9 subjects. Raw data were recorded from a rotary shutter video camera and digitized automatically by interfacing the videomotion analyzer with the digitizing board of a microcomputer. Three-dimensional orbital plots of the hip, knee, and ankle angle covariations revealed that the subjects used two different strategies to perform the skill. Phase plane analyses revealed a tight coupling between joint position and velocity in both conditions for the hip and the knee. Differences in movement kinematics between low and high arousal conditions were most visible in the ankle joint whose phase planes displayed an increased number of self-crossings (loops) in the high arousal condition. It was suggested that under high arousal, what was once automatic and smooth in terms of the ankle joint now comes under more volitional control, which is less smooth and efficient. Practical implications of the present study are suggested.</jats:p

Modélisation et analyse mathématique des effets de la stimulation cérébrale profonde dans la maladie de Parkinson

BORDEAUX2-BU Sci.Homme/Odontol. (330632102) / SudocSudocFranceF