@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{RealKotchoubeyKuebler2014,
  author    = {Real, Ruben G. L. and Kotchoubey, Boris and K{\"u}bler, Andrea},
  title     = {Studentized continuous wavelet transform (t-CWT) in the analysis of individual ERPs: real and simulated EEG data},
  doi       = {10.3389/fnins.2014.00279},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-113581},
  year      = {2014},
  abstract  = {This study aimed at evaluating the performance of the Studentized Continuous Wavelet Transform (t-CWT) as a method for the extraction and assessment of event-related brain potentials (ERP) in data from a single subject. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of the t-CWT were assessed and compared to a variety of competing procedures using simulated EEG data at six low signal-to-noise ratios. Results show that the t-CWT combines high sensitivity and specificity with favorable PPV and NPV. Applying the t-CWT to authentic EEG data obtained from 14 healthy participants confirmed its high sensitivity. The t-CWT may thus be well suited for the assessment of weak ERPs in single-subject settings.},
  language  = {en}
}
@article{MeuleKueblerBlechert2013,
  author    = {Meule, Adrian and K{\"u}bler, Andrea and Blechert, Jens},
  title     = {Time course of electrocortical food-cue responses during cognitive regulation of craving},
  series = {Frontiers in Psychology},
  volume    = {4},
  journal   = {Frontiers in Psychology},
  number    = {669},
  issn      = {1664-1078},
  doi       = {10.3389/fpsyg.2013.00669},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122566},
  year      = {2013},
  abstract  = {In our current obesogenic environment, exposure to visual food-cues can easily lead to craving and overeating because short-term, pleasurable effects of food intake dominate over the anticipated long-term adverse effects such as weight gain and associated health problems. Here we contrasted these two conditions during food-cue presentation while acquiring event-related potentials (ERPs) and subjective craving ratings. Female participants (n = 25) were presented with either high-calorie (HC) or low-calorie (LC) food images under instructions to imagine either immediate (NOW) or long-term effects (LATER) of consumption. On subjective ratings for HC foods, the LATER perspective reduced cravings as compared to the NOW perspective. For LC foods, by contrast, craving increased under the LATER perspective. Early ERPs (occipital N1, 150-200 ms) were sensitive to food type but not to perspective. Late ERPs (late positive potential, LPP, 350-550 ms) were larger in the HC-LATER condition than in all other conditions, possibly indicating that a cognitive focus on negative long-term consequences induced negative arousal. This enhancement for HC-LATER attenuated to the level of the LC conditions during the later slow wave (550-3000 ms), but amplitude in the HC-NOW condition was larger than in all other conditions, possibly due to a delayed appetitive response. Across all conditions, LPP amplitudes were positively correlated with self-reported emotional eating. In sum, results reveal that regulation effects are secondary to an early attentional analysis of food type and dynamically evolve over time. Adopting a long-term perspective on eating might promote a healthier food choice across a range of food types.},
  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}
}