Over the last few decades, the Brain-Computer Interfaces have been gradually making their way to the epicenter of scientific interest. Many scientists from all around the world have contributed to the state of the art in this scientific domain by developing numerous tools and methods for brain signal acquisition and processing. Such a spectacular progress would not be achievable without accompanying technological development to equip the researchers with the proper devices providing what is absolutely necessary for any kind of discovery as the core of every analysis: the data reflecting the brain activity. The common effort has resulted in pushing the whole domain to the point where the communication between a human being and the external world through BCI interfaces is no longer science fiction but nowadays reality. In this work we present the most relevant aspects of the BCIs and all the milestones that have been made over nearly 50-year history of this research domain. We mention people who were pioneers in this area as well as we highlight all the technological and methodological advances that have transformed something available and understandable by a very few into something that has a potential to be a breathtaking change for so many. Aiming to fully understand how the human brain works is a very ambitious goal and it will surely take time to succeed. However, even that fraction of what has already been determined is sufficient e.g., to allow impaired people to regain control on their lives and significantly improve its quality. The more is discovered in this domain, the more benefit for all of us this can potentially bring.
Objective. Brain–computer interfaces (BCIs) show promise as a direct line of communication between the brain and the outside world that could benefit those with impaired motor function. But the commands available for BCI operation are often limited by the ability of the decoder to differentiate between the many distinct motor or cognitive tasks that can be visualized or attempted. Simple binary command signals (e.g. right hand at rest versus movement) are therefore used due to their ability to produce large observable differences in neural recordings. At the same time, frequent command switching can impose greater demands on the subject’s focus and takes time to learn. Here, we attempt to decode the degree of effort in a specific movement task to produce a graded and more flexible command signal. Approach. Fourteen healthy human subjects (nine male, five female) responded to visual cues by squeezing a hand dynamometer to different levels of predetermined force, guided by continuous visual feedback, while the electroencephalogram (EEG) and grip force were monitored. Movement-related EEG features were extracted and modeled to predict exerted force. Main results. We found that event-related desynchronization (ERD) of the 8–30 Hz mu-beta sensorimotor rhythm of the EEG is separable for different degrees of motor effort. Upon four-fold cross-validation, linear classifiers were found to predict grip force from an ERD vector with mean accuracies across subjects of 53% and 55% for the dominant and non-dominant hand, respectively. ERD amplitude increased with target force but appeared to pass through a trough that hinted at non-monotonic behavior. Significance. Our results suggest that modeling and interactive feedback based on the intended level of motor effort is feasible. The observed ERD trends suggest that different mechanisms may govern intermediate versus low and high degrees of motor effort. This may have utility in rehabilitative protocols for motor impairments.
14 September 2022 in Advances in Materials Science and Engineering
Numerical and Experimental Assessment of Mechanical Properties of Biobased Epoxy Reinforced by Flax Fibres and Seashell Nanoparticles for Prosthetic Socket: Chronic diseases such as peripheral vascular and arteriosclerosis, wars, terrorist attacks, natural disasters, and traffic collisions are the major causes of the high demand for prostheses. The inadequacy of the typically used materials at reasonable prices and the high stiffness of these materials, which can negatively influence socket-limb load transfer, imply an urgent need to find alternatives to the existing prosthetic sockets. This work aims to use renewable, low-hazard, and low-cost natural flax fibres and seashell nanoparticles as substitutes for conventional reinforcement materials for prosthetic sockets. Seashell nanoparticles of 1, 3, and 5 weight fractions and 3 layers of flax fibres were integrated into biobased epoxy. Tensile and flexural properties of modified and unmodified specimens were assessed, and the finite element technique (ANSYS-20) was utilised to analyse and evaluate the mechanical characteristics of the specimens by observing the stress and total deformation. Here, all fabricated nanocomposites provided tensile and flexural strength higher than that of additive-free biobased epoxy. In addition, hybrid nanocomposites fabricated from 3 layers of flax fibres and 3 wt of seashell nanoparticles were revealed to have the highest mechanical properties compared with unmodified resin and biobased epoxy filled with other percentages of the reinforcement. These findings were further validated numerically in which the total deformation was shown to decrease after the addition of 3 wt of these nanoparticles within the nanocomposites. Moreover, the antibacterial activity proved its superb antimicrobial performance against various pathogenic microorganisms, namely, Staphylococcus aureus and E. coli. Accordingly, the fabricated composite systems are suggested to be an appropriate candidate for forming prosthetic sockets. These composites have promising mechanical and antibacterial properties, and they are made of affordable and available materials, which can be a suitable option, particularly in poor countries due to the fact that advanced technologies may require a substantial amount of money for equipment, surgery fees, and medical care.
Epilepsy is a very common disease affecting at least 1% of the population, comprising a number of over 50 million people. As many patients suffer from the drug-resistant version, the number of potential treatment methods is very small. However, since not only the treatment of epilepsy, but also its proper diagnosis or observation of brain signals from recordings are important research areas, in this paper, we address this very problem by developing a reliable technique for removing spikes and sharp transients from the baseline of the brain signal using a morphological filter. This allows much more precise identification of the so-called epileptic zone, which can then be resected, which is one of the methods of epilepsy treatment. We used eight patients with 5 KHz data set and depended upon the Staba 2002 algorithm as a reference to detect the ripples. We found that the average sensitivity and false detection rate of our technique are significant, and they are ∼94% and ∼14%, respectively.
Introduction: Accurate localization of the epileptogenic zone is essential for surgical treatment of drug-resistant epilepsy. Standard presurgical evaluations rely on multimodal neuroimaging techniques, but these may be limited by availability and interpretive challenges. This study aimed to assess the concordance between zones identified by ictal semiology and a novel distributed electrical source localization technique, CLARA, and to evaluate their impact on postsurgical outcomes.Methods: This retrospective study included 16 patients with at least three recorded seizures. Ictal semiology was analyzed subjectively using video electroencephalography (VEEG) by a multidisciplinary team of neurologists, neurophysiologists, and radiologists, who determined the presumed epileptogenic zone at the lobar level. CLARA was subsequently applied to identify the computed zone based on ictal and/or interictal biomarker activities. The concordance between the presumed and computed zones was assessed qualitatively. Postsurgical outcomes were examined in relation to the extent of resection of the CLARA-defined zones.Results: Among thirteen patients with sufficient data for analysis, qualitative comparison showed 77% concordance and 23% partial concordance between the presumed and computed zones. Postsurgical follow-up revealed seizure freedom in one patient with cavernoma following complete resection of the CLARA-defined zone. In contrast, patients with incomplete resection of this region continued to experience seizures.Discussion: The findings support the potential value of CLARA as an adjunctive neuroimaging technique in the presurgical evaluation of epilepsy. By providing an additional layer of verification, CLARA may improve the accuracy of epileptogenic zone localization when used alongside established modalities such as PET, SPECT, fMRI, and MRI. Its adaptability and lower resource requirements suggest particular utility in centers with limited access to advanced medical equipment and specialized personnel. Broader implementation of CLARA could enhance presurgical decision-making and contribute to improved surgical outcomes for epilepsy patients.