A practical guide to the selection of independent components of the electroencephalogram for artifact correction

Partial table of contents: Modelling Cardiac Excitation and Excitability (M. Boyett, et al.). Modelling Propagation in Excitable Media (A. Holden & A. Panfilov). Rotors, Fibrillation and Dimensionality (A. Winfree). A Mathematical Model of Cardiac Anatomy (P. Hunter, et al.). Finite Element Methods for Modelling Impulse Propagation in the Heart (J. Rogers, et al.). The Effects of Geometry and Fibre Orientation on Propagation and Extracellular Potentials in Myocardium (J. Keener & A. Panfilov). Forward and Inverse Problems in Electrocardiography (A. van Oosterom). Computational Electromechanics of the Heart (P. Hunter, et al.). Index.

Computational biology of the heart , edited by Alexander V. Panfilov and Arun V. Holden. Pp. 416. £70. 1997. ISBN 0 471 96020 9 (John Wiley & Sons).

Over recent years, brain-computer interface (BCI) has emerged as an alternative communication system between the human brain and an output device. Deciphered intents, after detecting electrical signals from the human scalp, are translated into control commands used to operate external devices, computer displays and virtual objects in the real-time. BCI provides an augmentative communication by creating a muscle-free channel between the brain and the output devices, primarily for subjects having neuromotor disorders, or trauma to nervous system, notably spinal cord injuries (SCI), and subjects with unaffected sensorimotor functions but disarticulated or amputated residual limbs. This review identifies the potentials of electroencephalography (EEG) based BCI applications for locomotion and mobility rehabilitation. Patients could benefit from its advancements such as, wearable lower-limb (LL) exoskeletons, orthosis, prosthesis, wheelchairs, and assistive-robot devices. The EEG communication signals employed by the aforementioned applications that also provide feasibility for future development in the field are sensorimotor rhythms (SMR), event-related potentials (ERP) and visual evoked potentials (VEP). The review is an effort to progress the development of user’s mental task related to LL for BCI reliability and confidence measures. As a novel contribution, the reviewed BCI control paradigms for wearable LL and assistive-robots are presented by a general control framework fitting in hierarchical layers. It reflects informatic interactions, between the user, the BCI operator, the shared controller, the robotic device and the environment. Each sub layer of the BCI operator is discussed in detail, highlighting the feature extraction, classification and execution methods employed by the various systems. All applications’ key features and their interaction with the environment are reviewed for the EEG-based activity mode recognition, and presented in form of a table. It is suggested to structure EEG-BCI controlled LL assistive devices within the presented framework, for future generation of intent-based multifunctional controllers. Despite the development of controllers, for BCI-based wearable or assistive devices that can seamlessly integrate user intent, practical challenges associated with such systems exist and have been discerned, which can be constructive for future developments in the field.

/pdf/eeg-based-bci-control-schemes-for-lower-limb-assistive-18pba6sv6o.pdf

EEG-Based BCI Control Schemes for Lower-Limb Assistive-Robots.

https://escholarship.org/content/qt4pj372zv/qt4pj372zv.pdf?t=qamu2p

Unidirectional brain to muscle connectivity reveals motor cortex control of leg muscles during stereotyped walking

Combining low-cost wireless EEG sensors with smartphones offers novel opportunities for mobile brain imaging in an everyday context. Here we present the technical details and validation of a framework for building multi-platform, portable EEG applications with real-time 3D source reconstruction. The system – Smartphone Brain Scanner – combines an off-the-shelf neuroheadset or EEG cap with a smartphone or tablet, and as such represents the first fully portable system for real-time 3D EEG imaging. We discuss the benefits and challenges, including technical limitations as well as details of real-time reconstruction of 3D images of brain activity. We present examples of brain activity captured in a simple experiment involving imagined finger tapping, which shows that the acquired signal in a relevant brain region is similar to that obtained with standard EEG lab equipment. Although the quality of the signal in a mobile solution using an off-the-shelf consumer neuroheadset is lower than the signal obtained using high-density standard EEG equipment, we propose mobile application development may offset the disadvantages and provide completely new opportunities for neuroimaging in natural settings.

/pdf/the-smartphone-brain-scanner-a-portable-real-time-2wlk66z03d.pdf

The Smartphone Brain Scanner: A Portable Real-Time Neuroimaging System

Exploration of chronobiological systems emerges as a growing research field within bioinformatics focusing on various applications in medicine, agriculture, and material sciences. From a systems biological perspective, the question arises whether biological control systems for regulation of oscillatory signals and their technical counterparts utilise similar mechanisms. If so, modelling approaches and parameterisation adopted from building blocks can help to identify general components for frequency control in circadian clocks along with gaining insight into mechanisms of clock synchronisation to external stimuli like the daily rhythm of sunlight and darkness. Phase-locked loops could be an interesting candidate in this context. Both, biology and engineering, can benefit from a unified view resulting from systems modularisation. In a first experimental study, we analyse a model of coupled repressilators. We demonstrate its ability to synchronise clock signals in a monofrequential manner. Several oscillators initially deviate in phase difference and frequency with respect to explicit reaction and diffusion rates. Accordingly, the duration of the synchronisation process depends on dedicated reaction and diffusion parameters whose settings still lack to be sufficiently captured analytically.

/pdf/biochemical-frequency-control-by-synchronisation-of-coupled-56vg7ge6ed.pdf

Biochemical frequency control by synchronisation of coupled repressilators: an in silico study of modules for circadian clock systems

Oscillatory signals turn out to be reliable carriers for efficient processing and propagation of information in both spheres, life sciences and engineering. Each living organism typically comprises a variety of inherent biological rhythms whose periodicities cover a widespread range of scales like split seconds, minutes, or hours, and sometimes even months or years. Due to different molecular principles of generation, those rhythms seem to persist independently from each other. Their combination and assembly in conjunction with recurrent environmental changes can lead to astonishing capabilities and evolutionary advantages. Motivated by the question on how populations of cicadas, an insect species living in the soil, sustain a synchronous life cycle of 17 years away from any known external stimulus of this duration, we aim at exploring potential underlying mechanisms by P system mediated assembly of a set of chemical control units. To this end, we identify a collection of core oscillators responsible for sinusoidal, spiking, and plated waveforms along with pass filters, switches, and modulators. Considering these units as genotypic elementary components, we utilise P system control for selection and (re-)assembly of units towards complex phenotypic systems. Two simulation case studies demonstrate the potential of this approach following the idea of artificial evolution. Our first study inspired by the cicadas converts a chemical frequency divider model 1:17 into counterparts of 1:3, 1:5, and 1:6 just by exchange of single units. In the second study adopted from the mammalian circadian clock system residing within the suprachiasmatic nucleus, we illustrate the stabilisation of the overall clock signal by addition of auxiliary core oscillators.

Maintenance of chronobiological information by p system mediated assembly of control units for oscillatory waveforms and frequency

Exploration of chronobiological systems emerges as a growi ng research field within bioinformatics focusing on various applications in medicine, agriculture, and mate ri l sciences. From a systems biological perspective, the question arises whether biological control systems for regulation of oscillative signals and their technical counterparts utilise similar mechanisms. If so, modelling approaches and parameterisation adopted from building blocks can help to identify general components for clock synchronisation. Phase-locked loops could be an interesting candidate in this context. Both, biology and en gineering, can benefit from a unified view. In a first experimental study, we analyse a model of coupled repressil ators. We demonstrate its ability to synchronise clock signals in a monofrequential manner. Several oscilla tors initially deviate in phase difference and frequency with respect to explicit reaction and diffusion rate s. Accordingly, the duration of the synchronisation process depends on dedicated reaction and diffusion parame ters whose settings still lack to be sufficiently captured by comprehensive tools like the Kuramoto approach .

Mathias Schumann

Papers

Biochemical frequency control by synchronisation of coupled repressilators: an in silico study of modules for circadian clock systems

Maintenance of chronobiological information by p system mediated assembly of control units for oscillatory waveforms and frequency

SYNCHRONISATION OF BIOLOGICAL CLOCK SIGNALS - Capturing Coupled Repressilators from a Control Systems Perspective