@article{WinterKernGalletal.2021, author = {Winter, Carla and Kern, Florian and Gall, Dominik and Latoschik, Marc Erich and Pauli, Paul and K{\"a}thner, Ivo}, title = {Immersive virtual reality during gait rehabilitation increases walking speed and motivation: a usability evaluation with healthy participants and individuals with multiple sclerosis and stroke}, series = {Journal of Neuroengineering and Rehabilitation}, volume = {18}, journal = {Journal of Neuroengineering and Rehabilitation}, number = {1}, issn = {1743-0003}, doi = {10.1186/s12984-021-00848-w}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258698}, year = {2021}, abstract = {Background: The rehabilitation of gait disorders in patients with multiple sclerosis (MS) and stroke is often based on conventional treadmill training. Virtual reality (VR)-based treadmill training can increase motivation and improve therapy outcomes. The present study evaluated an immersive virtual reality application (using a head-mounted display, HMD) for gait rehabilitation with patients to (1) demonstrate its feasibility and acceptance and to (2) compare its short-term effects to a semi-immersive presentation (using a monitor) and a conventional treadmill training without VR to assess the usability of both systems and estimate the effects on walking speed and motivation. Methods: In a within-subjects study design, 36 healthy participants and 14 persons with MS or stroke participated in each of the three experimental conditions (VR via HMD, VR via monitor, treadmill training without VR). Results: For both groups, the walking speed in the HMD condition was higher than in treadmill training without VR and in the monitor condition. Healthy participants reported a higher motivation after the HMD condition as compared with the other conditions. Importantly, no side effects in the sense of simulator sickness occurred and usability ratings were high. No increases in heart rate were observed following the VR conditions. Presence ratings were higher for the HMD condition compared with the monitor condition for both user groups. Most of the healthy study participants (89\%) and patients (71\%) preferred the HMD-based training among the three conditions and most patients could imagine using it more frequently. Conclusions For the first time, the present study evaluated the usability of an immersive VR system for gait rehabilitation in a direct comparison with a semi-immersive system and a conventional training without VR with healthy participants and patients. The study demonstrated the feasibility of combining a treadmill training with immersive VR. Due to its high usability and low side effects, it might be particularly suited for patients to improve training motivation and training outcome e. g. the walking speed compared with treadmill training using no or only semi-immersive VR. Immersive VR systems still require specific technical setup procedures. This should be taken into account for specific clinical use-cases during a cost-benefit assessment.}, language = {en} } @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} } @article{MirallesVargiuDauwalderetal.2015, author = {Miralles, Felip and Vargiu, Eloisa and Dauwalder, Stefan and Sol{\`a}, Marc and M{\"u}ller-Putz, Gernot and Wriessnegger, Selina C. and Pinegger, Andreas and K{\"u}bler, Andrea and Halder, Sebastian and K{\"a}thner, Ivo and Martin, Suzanne and Daly, Jean and Armstrong, Elaine and Guger, Christoph and Hinterm{\"u}ller, Christoph and Lowish, Hannah}, title = {Brain computer interface on track to home.}, series = {The Scientific World Journal}, volume = {2015}, journal = {The Scientific World Journal}, number = {623896}, doi = {10.1155/2015/623896}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149575}, year = {2015}, abstract = {The novel BackHome system offers individuals with disabilities a range of useful services available via brain-computer interfaces (BCIs), to help restore their independence. This is the time such technology is ready to be deployed in the real world, that is, at the target end users' home. This has been achieved by the development of practical electrodes, easy to use software, and delivering telemonitoring and home support capabilities which have been conceived, implemented, and tested within a user-centred design approach. The final BackHome system is the result of a 3-year long process involving extensive user engagement to maximize effectiveness, reliability, robustness, and ease of use of a home based BCI system. The system is comprised of ergonomic and hassle-free BCI equipment; one-click software services for Smart Home control, cognitive stimulation, and web browsing; and remote telemonitoring and home support tools to enable independent home use for nonexpert caregivers and users. BackHome aims to successfully bring BCIs to the home of people with limited mobility to restore their independence and ultimately improve their quality of life.}, language = {en} } @article{KaethnerKueblerHalder2015, author = {K{\"a}thner, Ivo and K{\"u}bler, Andrea and Halder, Sebastian}, title = {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}, series = {Journal of NeuroEngineering and Rehabilitation}, volume = {12}, journal = {Journal of NeuroEngineering and Rehabilitation}, number = {76}, doi = {10.1186/s12984-015-0071-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-145305}, year = {2015}, abstract = {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.}, language = {en} } @article{KaethnerKueblerHalder2015, author = {K{\"a}thner, Ivo and K{\"u}bler, Andrea and Halder, Sebastian}, title = {Rapid P300 brain-computer interface communication with a head-mounted display}, series = {Frontiers in Neuroscience}, volume = {9}, journal = {Frontiers in Neuroscience}, number = {207}, doi = {10.3389/fnins.2015.00207}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148520}, year = {2015}, abstract = {Visual ERP (P300) based brain-computer interfaces (BCIs) allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head-mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g., at a patient's bedside). To explore if similar accuracies can be achieved with a virtual reality (VR) headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS) to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5 x 5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A), the same 5 x 5 matrix filled the field of view of the user. In the second (glasses B), single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on three different occasions (glasses A condition only). For healthy participants, average online spelling accuracies were 94\% (15.5 bits/min) using three flash sequences for spelling with the monitor and glasses A and 96\% (16.2 bits/min) with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100\% (10 bits/min) using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100\% accuracy). We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely paralyzed persons.}, language = {en} } @article{KaethnerHalderHintermuelleretal.2017, author = {K{\"a}thner, Ivo and Halder, Sebastian and Hinterm{\"u}ller, Christoph and Espinosa, Arnau and Guger, Christoph and Miralles, Felip and Vargiu, Eloisa and Dauwalder, Stefan and Rafael-Palou, Xavier and Sol{\`a}, Marc and Daly, Jean M. and Armstrong, Elaine and Martin, Suzanne and K{\"u}bler, Andrea}, title = {A Multifunctional Brain-Computer Interface Intended for Home Use: An Evaluation with Healthy Participants and Potential End Users with Dry and Gel-Based Electrodes}, series = {Frontiers in Neuroscience}, volume = {11}, journal = {Frontiers in Neuroscience}, number = {286}, doi = {10.3389/fnins.2017.00286}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157925}, year = {2017}, abstract = {Current brain-computer interface (BCIs) software is often tailored to the needs of scientists and technicians and therefore complex to allow for versatile use. To facilitate home use of BCIs a multifunctional P300 BCI with a graphical user interface intended for non-expert set-up and control was designed and implemented. The system includes applications for spelling, web access, entertainment, artistic expression and environmental control. In addition to new software, it also includes new hardware for the recording of electroencephalogram (EEG) signals. The EEG system consists of a small and wireless amplifier attached to a cap that can be equipped with gel-based or dry contact electrodes. The system was systematically evaluated with a healthy sample, and targeted end users of BCI technology, i.e., people with a varying degree of motor impairment tested the BCI in a series of individual case studies. Usability was assessed in terms of effectiveness, efficiency and satisfaction. Feedback of users was gathered with structured questionnaires. Two groups of healthy participants completed an experimental protocol with the gel-based and the dry contact electrodes (N = 10 each). The results demonstrated that all healthy participants gained control over the system and achieved satisfactory to high accuracies with both gel-based and dry electrodes (average error rates of 6 and 13\%). Average satisfaction ratings were high, but certain aspects of the system such as the wearing comfort of the dry electrodes and design of the cap, and speed (in both groups) were criticized by some participants. Six potential end users tested the system during supervised sessions. The achieved accuracies varied greatly from no control to high control with accuracies comparable to that of healthy volunteers. Satisfaction ratings of the two end-users that gained control of the system were lower as compared to healthy participants. The advantages and disadvantages of the BCI and its applications are discussed and suggestions are presented for improvements to pave the way for user friendly BCIs intended to be used as assistive technology by persons with severe paralysis.}, language = {en} } @article{KaethnerEidelHaegeetal.2022, author = {K{\"a}thner, Ivo and Eidel, Matthias and H{\"a}ge, Anne-Sophie and Gram, Annika and Pauli, Paul}, title = {Observing physicians acting with different levels of empathy modulates later assessed pain tolerance}, series = {British Journal of Health Psychology}, volume = {27}, journal = {British Journal of Health Psychology}, number = {2}, doi = {10.1111/bjhp.12553}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258368}, pages = {434-448}, year = {2022}, abstract = {Objectives The patient-physician relationship is essential for treatment success. Previous studies demonstrated that physicians who behave empathic in their interaction with patients have a positive effect on health outcomes. In this study, we investigated if the mere perception of physicians as empathic/not empathic modulates pain despite an emotionally neutral interaction with the patients. Methods N = 60 women took part in an experimental study that simulated a clinical interaction. In the paradigm, each participant watched two immersive 360° videos via a head-mounted display from a patient's perspective. The physicians in the videos behaved either empathic or not empathic towards a third person. Importantly, these physicians remained emotionally neutral in the subsequent virtual interaction with the participants. Finally, participants received a controlled, painful pressure stimulus within the narratives of the videos. Results The physicians in the high compared with the low empathy videos were rated as more empathic and more likable, indicating successful experimental manipulation. In spite of later neutral behaviour of physicians, this short observation of physicians' behaviour towards a third person was sufficient to modulate pain tolerance of the participants. Conclusions The finding of this study that the mere observation of physicians' behaviour towards a third person modulates pain, despite a neutral direct interaction with the participants, has important clinical implications. Further, the proposed paradigm enables investigating aspects of patient-physician communication that are difficult to examine in a clinical setting.}, language = {en} } @article{KaethnerBaderPauli2019, author = {K{\"a}thner, Ivo and Bader, Thomas and Pauli, Paul}, title = {Heat pain modulation with virtual water during a virtual hand illusion}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-55407-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202221}, pages = {19137}, year = {2019}, abstract = {Immersive virtual reality is a powerful method to modify the environment and thereby influence experience. The present study used a virtual hand illusion and context manipulation in immersive virtual reality to examine top-down modulation of pain. Participants received painful heat stimuli on their forearm and placed an embodied virtual hand (co-located with their real one) under a virtual water tap, which dispensed virtual water under different experimental conditions. We aimed to induce a temperature illusion by a red, blue or white light suggesting warm, cold or no virtual water. In addition, the sense of agency was manipulated by allowing participants to have high or low control over the virtual hand's movements. Most participants experienced a thermal sensation in response to the virtual water and associated the blue and red light with cool/cold or warm/hot temperatures, respectively. Importantly, the blue light condition reduced and the red light condition increased pain intensity and unpleasantness, both compared to the control condition. The control manipulation influenced the sense of agency, but did not influence pain ratings. The large effects revealed in our study suggest that context effects within an embodied setting in an immersive virtual environment should be considered within VR based pain therapy.}, language = {en} }