Truncated RAP-MUSIC (TRAP-MUSIC) for MEG and EEG source localization

Electrically active brain regions can be located applying MUltiple SIgnal Classification (MUSIC) on magneto-or electroencephalographic (MEG; EEG) data. We introduce a new MUSIC method, called truncated recursively-applied-and-projected MUSIC (TRAP-MUSIC). It corrects a hidden deficiency of the conventional RAP-MUSIC algorithm, which prevents estimation of the true number of brain-signal sources accurately. The correction is done by applying a sequential dimension reduction to the signal-subspace projection. We show that TRAP-MUSIC significantly improves the performance of MUSIC-type localization; in particular, it successfully and robustly locates active brain regions and estimates their number. We compare TRAP-MUSIC and RAP-MUSIC in simulations with varying key parameters, e.g., signal-to-noise ratio, correlation between source time-courses, and initial estimate for the dimension of the signal space. In addition, we validate TRAP-MUSIC with measured MEG data. We suggest that with the proposed TRAP-MUSIC method, MUSIC-type localization could become more reliable and suitable for various online and offline MEG and EEG applications.Peer reviewe

Beyond rest and quiescence (endodormancy and ecodormancy) : A novel model for quantifying plant-environment interaction in bud dormancy release

Bud dormancy of plants has traditionally been explained either by physiological growth arresting conditions in the bud or by unfavourable environmental conditions, such as non-growth-promoting low air temperatures. This conceptual dichotomy has provided the framework also for developing process-based plant phenology models. Here, we propose a novel model that in addition to covering the classical dichotomy as a special case also allows the quantification of an interaction of physiological and environmental factors. According to this plant-environment interaction suggested conceptually decades ago, rather than being unambiguous, the concept of "non-growth-promoting low air temperature" depends on the dormancy status of the plant. We parameterized the model with experimental results of growth onset for seven boreal plant species and found that based on the strength of the interaction, the species can be classified into three dormancy types, only one of which represents the traditional dichotomy. We also tested the model with four species in an independent experiment. Our study suggests that interaction of environmental and physiological factors may be involved in many such phenomena that have until now been considered simply as plant traits without any considerations of effects of the environmental factors.Peer reviewe

Post-translocational folding of secretory proteins in Gram-positive bacteria

AbstractThe transport of proteins from their site of synthesis in the cytoplasm to their functional location is an essential characteristic of all living cells. In Gram-positive bacteria the majority of proteins that are translocated across the cytoplasmic membrane are delivered to the membrane–cell wall interface in an essentially unfolded form. They must then be folded into their native configuration in an environment that is dominated by a high density of immobilised negative charge—in essence an ion exchange resin. It is essential to the viability of the cell that these proteins do not block the translocation machinery in the membrane, form illegitimate interactions with the cell wall or, through intermolecular interactions, form insoluble aggregates. Native Gram-positive proteins therefore have intrinsic folding characteristics that facilitate their rapid folding, and this is assisted by a variety of folding factors, including enzymes, peptides and metal ions. Despite these intrinsic and extrinsic factors, secretory proteins do misfold, particularly if the cell is subjected to certain types of stress. Consequently, Gram-positive bacteria such as Bacillus subtilis encode membrane- and cell wall-associated proteases that act as a quality control machine, clearing misfolded or otherwise aberrant proteins from the translocase and the cell wall

Exploring Twitter as a game platform; strategies and opportunities for microblogging-based games

Recent years have seen the massive daily engagement of players with games that are integrated with online social networking sites, such as Facebook. However, few games have successfully created engaging experiences through integration with microblogging websites. In this paper, we explore the opportunities and challenges in using Twitter as a platform for playing games, through the case study of the game Hashtag Dungeon, a dungeon-crawling game that uses Twitter for collaborative creation of game content. Two studies were carried out. A quantitative user study with 32 participants demonstrated that players found the game engaging and rewarding. A follow-up qualitative study with 8 participants suggests that Twitter integration in this game is meaningful, but that there are concerns over the impact of the game on players’ Twitter profiles. Based on findings from both studies, we propose strategies for the design of Microblogging-based games, and discuss wider implications of social media integration in games

Antibodies to decorin-binding protein B (DbpB) in the diagnosis of Lyme neuroborreliosis in children

Peer reviewe

The Unique Determination of Neuronal Currents in the Brain via Magnetoencephalography

The problem of determining the neuronal current inside the brain from measurements of the induced magnetic field outside the head is discussed under the assumption that the space occupied by the brain is approximately spherical. By inverting the Geselowitz equation, the part of the current which can be reconstructed from the measurements is precisely determined. This actually consists of only certain moments of one of the two functions specifying the tangential part of the current. The other function specifying the tangential part of the current as well as the radial part of the current are completely arbitrary. However, it is also shown that with the assumption of energy minimization, the current can be reconstructed uniquely. A numerical implementation of this unique reconstruction is also presented

TMS-EEG: From basic research to clinical applications

Proceeding volume: 1626Transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) is a powerful technique for non-invasively studying cortical excitability and connectivity. The combination of TMS and EEG has widely been used to perform basic research and recently has gained importance in different clinical applications. In this paper, we will describe the physical and biological principles of TMS-EEG and different applications in basic research and clinical applications. We will present methods based on independent component analysis (ICA) for studying the TMS-evoked EEG responses. These methods have the capability to remove and suppress large artifacts, making it feasible, for instance, to study language areas with TMS-EEG. We will discuss the different applications and limitations of TMS and TMS-EEG in clinical applications. Potential applications of TMS are presented, for instance in neurosurgical planning, depression and other neurological disorders. Advantages and disadvantages of TMS-EEG and its variants such as repetitive TMS (rTMS) are discussed in comparison to other brain stimulation and neuroimaging techniques. Finally, challenges that researchers face when using this technique will be summarized.Peer reviewe

Closed-loop optimization of transcranial magnetic stimulation with electroencephalography feedback

Background: Transcranial magnetic stimulation (TMS) is widely used in brain research and treatment of various brain dysfunctions. However, the optimal way to target stimulation and administer TMS therapies, for example, where and in which electric field direction the stimuli should be given, is yet to be determined. Objective: To develop an automated closed-loop system for adjusting TMS parameters (in this work, the stimulus orientation) online based on TMS-evoked brain activity measured with electroencephalography (EEG). Methods: We developed an automated closed-loop TMS-EEG set-up. In this set-up, the stimulus parameters are electronically adjusted with multi-locus TMS. As a proof of concept, we developed an algorithm that automatically optimizes the stimulation orientation based on single-trial EEG responses. We applied the algorithm to determine the electric field orientation that maximizes the amplitude of the TMS-EEG responses. The validation of the algorithm was performed with six healthy volunteers, repeating the search twenty times for each subject. Results: The validation demonstrated that the closed-loop control worked as desired despite the large variation in the single-trial EEG responses. We were often able to get close to the orientation that maximizes the EEG amplitude with only a few tens of pulses. Conclusion: Optimizing stimulation with EEG feedback in a closed-loop manner is feasible and enables effective coupling to brain activity. (C) 2022 The Author(s). Published by Elsevier Inc.Peer reviewe

Desingularization of vortices for the Euler equation

We study the existence of stationary classical solutions of the incompressible Euler equation in the plane that approximate singular stationnary solutions of this equation. The construction is performed by studying the asymptotics of equation -\eps^2 \Delta u^\eps=(u^\eps-q-\frac{\kappa}{2\pi} \log \frac{1}{\eps})_+^p with Dirichlet boundary conditions and $q$ a given function. We also study the desingularization of pairs of vortices by minimal energy nodal solutions and the desingularization of rotating vortices.Comment: 40 page