User-centered design in brain–computer interfaces — a case study

The array of available brain–computer interface (BCI) paradigms has continued to grow, and so has the corresponding set of machine learning methods which are at the core of BCI systems. The latter have evolved to provide more robust data analysis solutions, and as a consequence the proportion of healthy BCI users who can use a BCI successfully is growing. With this development the chances have increased that the needs and abilities of specific patients, the end-users, can be covered by an existing BCI approach. However, most end-users who have experienced the use of a BCI system at all have encountered a single paradigm only. This paradigm is typically the one that is being tested in the study that the end-user happens to be enrolled in, along with other end-users. Though this corresponds to the preferred study arrangement for basic research, it does not ensure that the end-user experiences a working BCI. In this study, a different approach was taken; that of a user-centered design. It is the prevailing process in traditional assistive technology. Given an individual user with a particular clinical profile, several available BCI approaches are tested and – if necessary – adapted to him/her until a suitable BCI system is found

Χρήση διεπαφών εγκεφάλου-υπολογιστή στην αποκατάσταση επικοινωνίας ασθενών με Σύνδρομο Εγκλεισμού

H παρούσα συστηματική ανασκόπηση αφορά τη χρήση διεπαφών εγκεφάλου-υπολογιστή στην αποκατάσταση επικοινωνίας ασθενών με Σύνδρομο Εγκλεισμού. Συγκεκριμένα, εξετάζει τις μελέτες που πραγματοποιήθηκαν την τελευταία πενταετία με επεμβατικές/ημι-επεμβατικές αλλά και μη επεμβατικές διεπαφές στο σύνδρομο αυτό. Η μεγαλύτερη πρόκληση που είχαν να ξεπεράσουν οι μελέτες αυτές ήταν η επίτευξη αυτόνομης επικοινωνίας, ιδιαίτερα σε ασθενείς με Πλήρες Συνδρόμου Εγκλεισμού. Οι μελέτες έδειξαν θετικά αποτελέσματα στην πρόοδο της ανάπτυξης της τεχνολογίας αυτής, με τις μη επεμβατικές διεπαφές εγκεφάλου-υπολογιστή να χρησιμοποιούνται στην πλειοψηφία για την αποκατάσταση επικοινωνίας. Στο διάστημα της τελευταίας πενταετίας βρέθηκαν δεκαπέντε μελέτες που να αφορούν μη επεμβατικές διεπαφές εγκεφάλου-υπολογιστή και να ανταποκρίνονται στα κριτήρια ένταξης της συγκεκριμένης συστηματικής ανασκόπησης, ενώ μόνο δύο μελέτες που να αφορούν επεμβατικές/ημι-επεμβατικές διεπαφές εγκεφάλου-υπολογιστή. Υπήρξε εξέλιξη και στην αποτελεσματικότητα των διεπαφών εγκεφάλου-υπολογιστή στην επικοινωνία σε ασθενείς με Πλήρες Σύνδρομο Εγκλεισμού, λόγου χάρη η διεπαφή mindBEAGLE, η οποία πέτυχε για πρώτη φορά μεγαλύτερη ακρίβεια στην επικοινωνία σε μικρό χρονικό διάστημα. Πρόοδος υπήρξε και σε άλλα είδη μη επεμβατικών διεπαφών εγκεφάλου-υπολογιστή, όπως διεπαφές με βάση τα οπτικά προκλητά δυναμικά σταθερής κατάστασης, διεπαφή λειτουργικής φασματοσκοπίας εγγύς υπερύθρου και διεπαφή με βάση το ακουστικό ηλεκτροοφθαλμογράφημα. Δεδομένου, ότι ο συγκεκριμένος πληθυσμός στις έρευνες δεν ήταν πολύ μεγάλος ώστε να υπάρχουν τυχαιοποιημένες ελεγχόμενες μελέτες, τα αποτελέσματα πρέπει να επιβεβαιωθούν στο μέλλον με περαιτέρω μελέτες και μεγαλύτερο πληθυσμό.This systematic review addresses the use of brain-computer interfaces in the communication rehabilitation of patients with Locked-in Syndrome. Specifically, it examines the studies conducted in the last five years on invasive/semi-invasive and non-invasive interfaces in this syndrome. The most significant challenge that these studies had to overcome, was to achieve autonomous communication, especially in patients with Complete Locked-in Syndrome. Studies have shown progress of the development of this technology, with non-invasive interfaces being used in the majority for the communication rehabilitation. Fifteen studies, meeting the inclusion criteria of this systematic review, are about non-invasive brain-computer interfaces, while only two studies examine invasive/semi-invasive brain-computer interfaces. There has also been improvement in the effectiveness of brain-computer interfaces in communication in patients with Complete Locked-in Syndrome, for example the mindBEAGLE interface, which for the first time attained greater accuracy in communication in a short period of time. Other types of non-invasive brain-computer interfaces, such as brain-computer interfaces based on steady-state visual-evoked potentials, brain-computer interface based on functional near-infrared spectroscopy, and an auditory electrooculogram-based communication system, have also improved performance. Given that the specific population in the studies was not large enough to conduct randomized controlled trials, the results need to be confirmed in the future with further studies and a larger population

The cost of space independence in P300-BCI spellers.

Background: Though non-invasive EEG-based Brain Computer Interfaces (BCI) have been researched extensively over the last two decades, most designs require control of spatial attention and/or gaze on the part of the user. Methods: In healthy adults, we compared the offline performance of a space-independent P300-based BCI for spelling words using Rapid Serial Visual Presentation (RSVP), to the well-known space-dependent Matrix P300 speller. Results: EEG classifiability with the RSVP speller was as good as with the Matrix speller. While the Matrix speller’s performance was significantly reliant on early, gaze-dependent Visual Evoked Potentials (VEPs), the RSVP speller depended only on the space-independent P300b. However, there was a cost to true spatial independence: the RSVP speller was less efficient in terms of spelling speed. Conclusions: The advantage of space independence in the RSVP speller was concomitant with a marked reduction in spelling efficiency. Nevertheless, with key improvements to the RSVP design, truly space-independent BCIs could approach efficiencies on par with the Matrix speller. With sufficiently high letter spelling rates fused with predictive language modelling, they would be viable for potential applications with patients unable to direct overt visual gaze or covert attentional focus

BCI-Based Navigation in Virtual and Real Environments

A Brain-Computer Interface (BCI) is a system that enables people to control an external device with their brain activity, without the need of any muscular activity. Researchers in the BCI field aim to develop applications to improve the quality of life of severely disabled patients, for whom a BCI can be a useful channel for interaction with their environment. Some of these systems are intended to control a mobile device (e. g. a wheelchair). Virtual Reality is a powerful tool that can provide the subjects with an opportunity to train and to test different applications in a safe environment. This technical review will focus on systems aimed at navigation, both in virtual and real environments.This work was partially supported by the Innovation, Science and Enterprise Council of the Junta de Andalucía (Spain), project P07-TIC-03310, the Spanish Ministry of Science and Innovation, project TEC 2011-26395 and by the European fund ERDF

Electrophysiological investigations of brain function in coma, vegetative and minimally conscious patients.

Electroencephalographic activity in the context of disorders of consciousness is a swiss knife like tool that can evaluate different aspects of cognitive residual function, detect consciousness and provide a mean to communicate with the outside world without using muscular channels. Standard recordings in the neurological department offer a first global view of the electrogenesis of a patient and can spot abnormal epileptiform activity and therefore guide treatment. Although visual patterns have a prognosis value, they are not sufficient to provide a diagnosis between vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state (MCS) patients. Quantitative electroencephalography (qEEG) processes the data and retrieves features, not visible on the raw traces, which can then be classified. Current results using qEEG show that MCS can be differentiated from VS/UWS patients at the group level. Event Related Potentials (ERP) are triggered by varying stimuli and reflect the time course of information processing related to the stimuli from low-level peripheral receptive structures to high-order associative cortices. It is hence possible to assess auditory, visual, or emotive pathways. Different stimuli elicit positive or negative components with different time signatures. The presence of these components when observed in passive paradigms is usually a sign of good prognosis but it cannot differentiate VS/UWS and MCS patients. Recently, researchers have developed active paradigms showing that the amplitude of the component is modulated when the subject's attention is focused on a task during stimulus presentation. Hence significant differences between ERPs of a patient in a passive compared to an active paradigm can be a proof of consciousness. An EEG-based brain-computer interface (BCI) can then be tested to provide the patient with a communication tool. BCIs have considerably improved the past two decades. However they are not easily adaptable to comatose patients as they can have visual or auditory impairments or different lesions affecting their EEG signal. Future progress will require large databases of resting state-EEG and ERPs experiment of patients of different etiologies. This will allow the identification of specific patterns related to the diagnostic of consciousness. Standardized procedures in the use of BCIs will also be needed to find the most suited technique for each individual patient.Peer reviewe

A Comparison of a Brain-Computer Interface and an Eye Tracker: Is There a More Appropriate Technology for Controlling a Virtual Keyboard in an ALS Patient?

The ability of people affected by amyotrophic lateral sclerosis (ALS), muscular dystrophy or spinal cord injuries to physically interact with the environment, is usually reduced. In some cases, these patients suffer from a syndrome known as locked-in syndrome (LIS), defined by the patient’s inability to make any move-ment but blinks and eye movements. Tech communication systems available for people in LIS are very limited, being those based on eye-tracking and brain-computer interface (BCI) the most useful for these patients. A comparative study between both technologies in an ALS patient is carried out: an eye tracker and a visual P300-based BCI. The purpose of the study presented in this paper is to show that the choice of the technology could depend on user´s preference. The evaluation of performance, workload and other subjective measures will allow us to determine the usability of the systems. The obtained results suggest that, even if for this patient the BCI technology is more appropriate, the technology should be always tested and adapted for each user.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

BNCI systems as a potential assistive technology: ethical issues and participatory research in the BrainAble project

This paper highlights aspects related to current research and thinking about ethical issues in relation to Brain Computer Interface (BCI) and Brain-Neuronal Computer Interfaces (BNCI) research through the experience of one particular project, BrainAble, which is exploring and developing the potential of these technologies to enable people with complex disabilities to control computers. It describes how ethical practice has been developed both within the multidisciplinary research team and with participants. Results: The paper presents findings in which participants shared their views of the project prototypes, of the potential of BCI/BNCI systems as an assistive technology, and of their other possible applications. This draws attention to the importance of ethical practice in projects where high expectations of technologies, and representations of “ideal types” of disabled users may reinforce stereotypes or drown out participant “voices”. Conclusions: Ethical frameworks for research and development in emergent areas such as BCI/BNCI systems should be based on broad notions of a “duty of care” while being sufficiently flexible that researchers can adapt project procedures according to participant needs. They need to be frequently revisited, not only in the light of experience, but also to ensure they reflect new research findings and ever more complex and powerful technologies

Comparison of eye tracking, electrooculography and an auditory brain-computer interface for binary communication: a case study with a participant in the locked-in state

Background In this study, we evaluated electrooculography (EOG), an eye tracker and an auditory brain-computer interface (BCI) as access methods to augmentative and alternative communication (AAC). The participant of the study has been in the locked-in state (LIS) for 6 years due to amyotrophic lateral sclerosis. He was able to communicate with slow residual eye movements, but had no means of partner independent communication. We discuss the usability of all tested access methods and the prospects of using BCIs as an assistive technology. Methods Within four days, we tested whether EOG, eye tracking and a BCI would allow the participant in LIS to make simple selections. We optimized the parameters in an iterative procedure for all systems. Results The participant was able to gain control over all three systems. Nonetheless, due to the level of proficiency previously achieved with his low-tech AAC method, he did not consider using any of the tested systems as an additional communication channel. However, he would consider using the BCI once control over his eye muscles would no longer be possible. He rated the ease of use of the BCI as the highest among the tested systems, because no precise eye movements were required; but also as the most tiring, due to the high level of attention needed to operate the BCI. Conclusions In this case study, the partner based communication was possible due to the good care provided and the proficiency achieved by the interlocutors. To ease the transition from a low-tech AAC method to a BCI once control over all muscles is lost, it must be simple to operate. For persons, who rely on AAC and are affected by a progressive neuromuscular disease, we argue that a complementary approach, combining BCIs and standard assistive technology, can prove valuable to achieve partner independent communication and ease the transition to a purely BCI based approach. Finally, we provide further evidence for the importance of a user-centered approach in the design of new assistive devices

A Novel 9-Class Auditory ERP Paradigm Driving a Predictive Text Entry System

Brain–computer interfaces (BCIs) based on event related potentials (ERPs) strive for offering communication pathways which are independent of muscle activity. While most visual ERP-based BCI paradigms require good control of the user's gaze direction, auditory BCI paradigms overcome this restriction. The present work proposes a novel approach using auditory evoked potentials for the example of a multiclass text spelling application. To control the ERP speller, BCI users focus their attention to two-dimensional auditory stimuli that vary in both, pitch (high/medium/low) and direction (left/middle/right) and that are presented via headphones. The resulting nine different control signals are exploited to drive a predictive text entry system. It enables the user to spell a letter by a single nine-class decision plus two additional decisions to confirm a spelled word. This paradigm – called PASS2D – was investigated in an online study with 12 healthy participants. Users spelled with more than 0.8 characters per minute on average (3.4 bits/min) which makes PASS2D a competitive method. It could enrich the toolbox of existing ERP paradigms for BCI end users like people with amyotrophic lateral sclerosis disease in a late stage