@article{SimonKaethnerRufetal.2015, author = {Simon, Nadine and K{\"a}thner, Ivo and Ruf, Carolin A. and Pasqualotto, Emanuele and K{\"u}bler, Andrea and Halder, Sebastian}, title = {An auditory multiclass brain-computer interface with natural stimuli: Usability evaluation with healthy participants and a motor impaired end user}, series = {Frontiers in Human Neuroscience}, volume = {8}, journal = {Frontiers in Human Neuroscience}, number = {1039}, doi = {10.3389/fnhum.2014.01039}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-126450}, year = {2015}, abstract = {Brain-computer interfaces (BCIs) can serve as muscle independent communication aids. Persons, who are unable to control their eye muscles (e.g., in the completely locked-in state) or have severe visual impairments for other reasons, need BCI systems that do not rely on the visual modality. For this reason, BCIs that employ auditory stimuli were suggested. In this study, a multiclass BCI spelling system was implemented that uses animal voices with directional cues to code rows and columns of a letter matrix. To reveal possible training effects with the system, 11 healthy participants performed spelling tasks on 2 consecutive days. In a second step, the system was tested by a participant with amyotrophic lateral sclerosis (ALS) in two sessions. In the first session, healthy participants spelled with an average accuracy of 76\% (3.29 bits/min) that increased to 90\% (4.23 bits/min) on the second day. Spelling accuracy by the participant with ALS was 20\% in the first and 47\% in the second session. The results indicate a strong training effect for both the healthy participants and the participant with ALS. While healthy participants reached high accuracies in the first session and second session, accuracies for the participant with ALS were not sufficient for satisfactory communication in both sessions. More training sessions might be needed to improve spelling accuracies. The study demonstrated the feasibility of the auditory BCI with healthy users and stresses the importance of training with auditory multiclass BCIs, especially for potential end-users of BCI with disease.}, language = {en} } @phdthesis{Kaethner2015, author = {K{\"a}thner, Ivo R. J.}, title = {Auditory and visual brain-computer interfaces as communication aids for persons with severe paralysis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-135477}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2015}, abstract = {Brain-computer interfaces (BCIs) could provide a muscle-independent communication channel to persons with severe paralysis by translating brain activity into device commands. As a means of communication, in particular BCIs based on event-related potentials (ERPs) as control signal have been researched. Most of these BCIs rely on visual stimulation and have been investigated with healthy participants in controlled laboratory environments. In proof-of-principle studies targeted end users gained control over BCI systems; however, these systems are not yet established as an assistive technology for persons who would most benefit from them. The main aim of this thesis is to advance the usability of ERP-BCIs for target users. To this end, five studies with BCIs have been conducted that enabled users to communicate by focusing their attention on external stimuli. Two studies were conducted in order to demonstrate the advantages and to further improve the practical application of visual BCIs. In the first study, mental workload was experimentally manipulated during prolonged BCI operation. The study showed the robustness of the visual ERP-BCI since users maintained a satisfactory level of control despite constant distraction in the form of background noise. Moreover, neurophysiological markers that could potentially serve as indicators of high mental workload or fatigue were revealed. This is a first step towards future applications in which the BCI could adapt to the mental state of the user (e.g. pauses if high mental workload is detected to prevent false selections). In the second study, a head-mounted display (HMD), which assures that stimuli are presented in the field of view of the user, was evaluated. High accuracies and information transfer rates, similar to a conventional display, were achieved by healthy participants during a spelling task. Furthermore, a person in the locked-in state (LIS) gained control over the BCI using the HMD. The HMD might be particularly suited for initial communication attempts with persons in the LIS in situations, where mounting a conventional monitor is difficult or not feasible. Visual ERP-BCIs could prove valuable for persons with residual control over eye muscles and sufficient vision. However, since a substantial number of target users have limited control over eye movements and/or visual impairments, BCIs based on non-visual modalities are required. Therefore, a main aspect of this thesis was to improve an auditory paradigm that should enable motor impaired users to spell by focusing attention on different tones. The two conducted studies revealed that healthy participants were able to achieve high spelling performance with the BCI already in the first session and stress the importance of the choice of the stimulus material. The employed natural tones resulted in an increase in performance compared to a previous study that used artificial tones as stimuli. Furthermore, three out of five users with a varying degree of motor impairments could gain control over the system within the five conducted sessions. Their performance increased significantly from the first to the fifth session - an effect not previously observed for visual ERP-BCIs. Hence, training is particularly important when testing auditory multiclass BCIs with potential users. A prerequisite for user satisfaction is that the BCI technology matches user requirements. In this context, it is important to compare BCIs with already established assistive technology. Thus, the fifth study of this dissertation evaluated gaze dependent methods (EOG, eye tracking) as possible control signals for assistive technology and a binary auditory BCI with a person in the locked-in state. The study participant gained control over all tested systems and rated the ease of use of the BCI as the highest among the tested alternatives, but also rated it as the most tiring due to the high amount of attention that was needed for a simple selection. Further efforts are necessary to simplify operation of the BCI. The involvement of end users in all steps of the design and development process of BCIs will increase the likelihood that they can eventually be used as assistive technology in daily life. The work presented in this thesis is a substantial contribution towards the goal of re-enabling communication to users who cannot rely on motor activity to convey their thoughts.}, subject = {Gehirn-Computer Schnittstelle}, language = {en} } @article{ErlbeckMochtyKuebleretal.2017, author = {Erlbeck, Helena and Mochty, Ursula and K{\"u}bler, Andrea and Real, Ruben G. L.}, title = {Circadian course of the P300 ERP in patients with amyotrophic lateral sclerosis - implications for brain-computer interfaces (BCI)}, series = {BMC Neurology}, volume = {17}, journal = {BMC Neurology}, number = {3}, doi = {10.1186/s12883-016-0782-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157423}, year = {2017}, abstract = {Background: Accidents or neurodegenerative diseases like amyotrophic lateral sclerosis (ALS) can lead to progressing, extensive, and complete paralysis leaving patients aware but unable to communicate (locked-in state). Brain-computer interfaces (BCI) based on electroencephalography represent an important approach to establish communication with these patients. The most common BCI for communication rely on the P300, a positive deflection arising in response to rare events. To foster broader application of BCIs for restoring lost function, also for end-users with impaired vision, we explored whether there were specific time windows during the day in which a P300 driven BCI should be preferably applied. Methods: The present study investigated the influence of time of the day and modality (visual vs. auditory) on P300 amplitude and latency. A sample of 14 patients (end-users) with ALS and 14 healthy age matched volunteers participated in the study and P300 event-related potentials (ERP) were recorded at four different times (10, 12 am, 2, \& 4 pm) during the day. Results: Results indicated no differences in P300 amplitudes or latencies between groups (ALS patients v. healthy participants) or time of measurement. In the auditory condition, latencies were shorter and amplitudes smaller as compared to the visual condition. Conclusion: Our findings suggest applicability of EEG/BCI sessions in patients with ALS throughout normal waking hours. Future studies using actual BCI systems are needed to generalize these findings with regard to BCI effectiveness/efficiency and other times of day.}, language = {en} } @article{MatuzBirbaumerHautzingeretal., author = {Matuz, Tamara and Birbaumer, Niels and Hautzinger, Martin and K{\"u}bler, Andrea}, title = {Psychosocial adjustment to ALS: a longitudinal study}, series = {Frontiers in Psychology}, volume = {6}, journal = {Frontiers in Psychology}, number = {1197}, issn = {1664-1078}, doi = {10.3389/fpsyg.2015.01197}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-190208}, abstract = {For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to ALS. We aimed to investigate the evolution of psychosocial adjustment to ALS and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55\% of the variance of severity of depressive symptoms and 47\% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to ALS. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with ALS.}, language = {en} } @article{KueblerHautzingerLudolphetal.2014, author = {K{\"u}bler, Andrea and Hautzinger, Martin and Ludolph, Albert and Dickhaus, Thorsten and Real, Ruben G. L.}, title = {Well-being in amyotrophic lateral sclerosis: a pilot experience sampling study}, doi = {10.3389/fpsyg.2014.00704}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-113057}, year = {2014}, abstract = {Objective: The aim of this longitudinal study was to identify predictors of instantaneous well-being in patients with amyotrophic lateral sclerosis (ALS). Based on flow theory well-being was expected to be highest when perceived demands and perceived control were in balance, and that thinking about the past would be a risk factor for rumination which would in turn reduce well-being. Methods: Using the experience sampling method, data on current activities, associated aspects of perceived demands, control, and well-being were collected from 10 patients with ALS three times a day for two weeks. Results: Results show that perceived control was uniformly and positively associated with well-being, but that demands were only positively associated with well-being when they were perceived as controllable. Mediation analysis confirmed thinking about the past, but not thinking about the future, to be a risk factor for rumination and reduced well-being. Discussion: Findings extend our knowledge of factors contributing to well-being in ALS as not only perceived control but also perceived demands can contribute to well-being. They further show that a focus on present experiences might contribute to increased well-being.}, language = {en} }