@phdthesis{Roemmler2004, author = {R{\"o}mmler, Josefine}, title = {Zusammenhang zwischen Fehlermonitoring, Pers{\"o}nlichkeitsmerkmalen und Serotonintransporterpolymorphismus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-15605}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2004}, abstract = {Bei Wahlreaktionszeitaufgaben werden w{\"a}hrend eines fehlerinduzierenden Paradigmas im Frontallappen Potential{\"a}nderungen erzeugt. Diese im EEG sichtbaren Potentiale werden ereignis-korrelierte Potentiale (EKP´s) genannt. Bei den EKP´s nach Fehleingaben ist besonders die „error-related negativity" (ERN) sowie die Positivit{\"a}t P300 (Pe) hervorzuheben. In dieser Arbeit wurde die ERN sowie die Pe bei 39 Probanden untersucht und genauer klassifiziert. Zus{\"a}tzlich wurde mit Hilfe der Quellenlokalisationsmethode LORETA dreidimensional die genaue Lokalisation der ERN bestimmt. Auf der Suche nach Beeinflussungsfaktoren der ERN-Amplitude wurden bei den Probanden verschiedene Pers{\"o}nlichkeitsmerkmale sowie die Genpolymorphismen des 5-HTTs (5-Hydroxythryptophantransporter), des D4(Dopamin)-Rezeptors und der MAO A (Monoaminooxidase A) bestimmt und nach m{\"o}glichen Zusammenh{\"a}ngen zwischen diesen Faktoren gesucht. Es ergab sich ein signifikanter Unterschied (Z = - 2,00, p < 0,05) f{\"u}r zwei nach Geschlecht und Alter angepassten Gruppen des 5-HTT-Polymorphismus in der H{\"o}he der ERN-Amplitude. So hatten Probanden mit ein oder zwei Kopien des kurzen Allels (S/S, S/L) des 5-HTT-Polymorphismus eine h{\"o}here Ausbildung der ERN-Amplitude (- 5,44 µV ± 2,99 µV) als Probanden mit zwei Kopien des langen Allels (L/L: - 3,77 µV ± 2,53 µV). Außerdem konnte nachgewiesen werden, dass Probanden mit einer oder zwei Kopien des kurzen Allels des 5-HTT-Polymorphismus (S/S, S/L: 15,86 ± 3,82) niedrigere Werte f{\"u}r das Pers{\"o}nlichkeitsmerkmal NA (negativer Affekt) besaßen (Z = - 2,899, p < 0,005, L/L: 20,82 ± 5,12). Zwischen der H{\"o}he der ERN-Amplitude und den Werten der Pers{\"o}nlichkeitsmerkmale ergab sich hingegen kein signifikanter Zusammenhang. Somit scheint der 5-HTT-Polymorphismus mit einer erh{\"o}hten Ansprechbarkeit des Vorderhirns sowie einem negativeren Affekt einherzugehen. Außerdem st{\"u}tzen diese Ergebnisse die Vorstellung, dass die Funktion des pr{\"a}frontalen Kortex von der genetischen Variation des Serotonintransporters beeinflusst wird.}, language = {de} } @article{EidelKuebler2020, author = {Eidel, Matthias and K{\"u}bler, Andrea}, title = {Wheelchair Control in a Virtual Environment by Healthy Participants Using a P300-BCI Based on Tactile Stimulation: Training Effects and Usability}, series = {Frontiers in Human Neuroscience}, volume = {14}, journal = {Frontiers in Human Neuroscience}, issn = {1662-5161}, doi = {10.3389/fnhum.2020.00265}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207775}, year = {2020}, abstract = {Tactile stimulation is less frequently used than visual for brain-computer interface (BCI) control, partly because of limitations in speed and accuracy. Non-visual BCI paradigms, however, may be required for patients who struggle with vision dependent BCIs because of a loss of gaze control. With the present study, we attempted to replicate earlier results by Herweg et al. (2016), with several minor adjustments and a focus on training effects and usability. We invited 16 healthy participants and trained them with a 4-class tactile P300-based BCI in five sessions. Their main task was to navigate a virtual wheelchair through a 3D apartment using the BCI. We found significant training effects on information transfer rate (ITR), which increased from a mean of 3.10-9.50 bits/min. Further, both online and offline accuracies significantly increased with training from 65\% to 86\% and 70\% to 95\%, respectively. We found only a descriptive increase of P300 amplitudes at Fz and Cz with training. Furthermore, we report subjective data from questionnaires, which indicated a relatively high workload and moderate to high satisfaction. Although our participants have not achieved the same high performance as in the Herweg et al. (2016) study, we provide evidence for training effects on performance with a tactile BCI and confirm the feasibility of the paradigm.}, language = {en} } @phdthesis{Kaese2011, author = {K{\"a}se, Mirjam}, title = {Transkranielle Theta Burst Behandlung depressiver Patienten: Untersuchung der Wirkung auf evozierte Potentiale in einem Oddball Paradigma}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69314}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Ziel der vorliegenden Arbeit war es die Wirksamkeit einer Behandlung mit Transkranieller Magnetstimulation bei depressiven Patienten zu untersuchen. Der Behandlungserfolg wurde mit depressionsspezfischen Frageb{\"o}gen, der Testleistung in einer kognitiven Aufgabe und ereigniskorrelierten Potentialen im EEG objektiviert. Es konnte nicht abschließend gekl{\"a}rt werden, ob die Theta-Burst-Stimulation in der Therapie depressiver Patienten geeignet ist. Es fanden sich allerdings Hinweise darauf, dass die pr{\"a}frontal applizierte Behandlung Ver{\"a}nderungen in den frontal generierten ereigniskorrelierten Potentialen bewirkte.}, subject = {Chronische Depression}, language = {de} } @article{KaufmannHerwegKuebler2014, author = {Kaufmann, Tobias and Herweg, Andreas and K{\"u}bler, Andrea}, title = {Toward brain-computer interface based wheelchair control utilizing tactually-evoked event-related potentials}, doi = {10.1186/1743-0003-11-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-110042}, year = {2014}, abstract = {Background People with severe disabilities, e.g. due to neurodegenerative disease, depend on technology that allows for accurate wheelchair control. For those who cannot operate a wheelchair with a joystick, brain-computer interfaces (BCI) may offer a valuable option. Technology depending on visual or auditory input may not be feasible as these modalities are dedicated to processing of environmental stimuli (e.g. recognition of obstacles, ambient noise). Herein we thus validated the feasibility of a BCI based on tactually-evoked event-related potentials (ERP) for wheelchair control. Furthermore, we investigated use of a dynamic stopping method to improve speed of the tactile BCI system. Methods Positions of four tactile stimulators represented navigation directions (left thigh: move left; right thigh: move right; abdomen: move forward; lower neck: move backward) and N = 15 participants delivered navigation commands by focusing their attention on the desired tactile stimulus in an oddball-paradigm. Results Participants navigated a virtual wheelchair through a building and eleven participants successfully completed the task of reaching 4 checkpoints in the building. The virtual wheelchair was equipped with simulated shared-control sensors (collision avoidance), yet these sensors were rarely needed. Conclusion We conclude that most participants achieved tactile ERP-BCI control sufficient to reliably operate a wheelchair and dynamic stopping was of high value for tactile ERP classification. Finally, this paper discusses feasibility of tactile ERPs for BCI based wheelchair control.}, language = {en} } @article{KleihHerwegKaufmannetal.2015, author = {Kleih, Sonja C. and Herweg, Andreas and Kaufmann, Tobias and Staiger-S{\"a}lzer, Pit and Gerstner, Natascha and K{\"u}bler, Andrea}, title = {The WIN-speller: a new intuitive auditory brain-computer interface spelling application}, series = {Frontiers in Neuroscience}, volume = {9}, journal = {Frontiers in Neuroscience}, doi = {10.3389/fnins.2015.00346}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125972}, pages = {346}, year = {2015}, abstract = {The objective of this study was to test the usability of a new auditory Brain-Computer Interface (BCI) application for communication. We introduce a word based, intuitive auditory spelling paradigm the WIN-speller. In the WIN-speller letters are grouped by words, such as the word KLANG representing the letters A, G, K, L, and N. Thereby, the decoding step between perceiving a code and translating it to the stimuli it represents becomes superfluous. We tested 11 healthy volunteers and four end-users with motor impairment in the copy spelling mode. Spelling was successful with an average accuracy of 84\% in the healthy sample. Three of the end-users communicated with average accuracies of 80\% or higher while one user was not able to communicate reliably. Even though further evaluation is required, the WIN-speller represents a potential alternative for BCI based communication in end-users.}, language = {en} } @article{BertiVosselGamer2017, author = {Berti, Stefan and Vossel, Gerhard and Gamer, Matthias}, title = {The orienting response in healthy aging: Novelty P3 indicates no general decline but reduced efficacy for fast stimulation rates}, series = {Frontiers in Psychology}, volume = {8}, journal = {Frontiers in Psychology}, doi = {10.3389/fpsyg.2017.01780}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173651}, year = {2017}, abstract = {Automatic orienting to unexpected changes in the environment is a pre-requisite for adaptive behavior. One prominent mechanism of automatic attentional control is the Orienting Response (OR). Despite the fundamental significance of the OR in everyday life, only little is known about how the OR is affected by healthy aging. We tested this question in two age groups (19-38 and 55-72 years) and measured skin-conductance responses (SCRs) and event-related brain potentials (ERPs) to novels (i.e., short environmental sounds presented only once in the experiment; 10\% of the trials) compared to standard sounds (600 Hz sinusoidal tones with 200 ms duration; 90\% of the trials). Novel and standard stimuli were presented in four conditions differing in the inter-stimulus interval (ISI) with a mean ISI of either 10, 3, 1, or 0.5 s (blocked presentation). In both age groups, pronounced SCRs were elicited by novels in the 10 s ISI condition, suggesting the elicitation of stable ORs. These effects were accompanied by pronounced N1 and frontal P3 amplitudes in the ERP, suggesting that automatic novelty processing and orientation of attention are effective in both age groups. Furthermore, the SCR and ERP effects declined with decreasing ISI length. In addition, differences between the two groups were observable with the fastest presentation rates (i.e., 1 and 0.5 s ISI length). The most prominent difference was a shift of the peak of the frontal positivity from around 300 to 200 ms in the 19-38 years group while in the 55-72 years group the amplitude of the frontal P3 decreased linearly with decreasing ISI length. Taken together, this pattern of results does not suggest a general decline in processing efficacy with healthy aging. At least with very rare changes (here, the novels in the 10 s ISI condition) the OR is as effective in healthy older adults as in younger adults. With faster presentation rates, however, the efficacy of the OR decreases. This seems to result in a switch from novelty to deviant processing in younger adults, but less so in the group of older adults.}, 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{StrikDierksFranzeketal.1994, author = {Strik, Werner K. and Dierks, Thomas and Franzek, Ernst and St{\"o}ber, Gerald and Maurer, Konrad}, title = {P300 in Schizophrenia: Interactions between Amplitudes and Topography}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-63351}, year = {1994}, abstract = {Low P300 amplitudes and topographical asymmetries have been reponed in schizophrenic patients, but reference-independent amplitude assessment failed to replicate reduced amplitudes. P300 amplitude is conventially assessed at midline electrodes (PZ), anti asymmetric topography as reported in schizophrenics, may conj'ound this measurement. We lnvestigated the possible Interaction between P300 ropography and assessments of amplitudes. ln 41 clinically stable schizophrenics and 31 normal controls, the generalfinding ofreduced amplitudes at the P'l electrode and topographical asymmetrles in the patient group were replicated. ln both groups, a.symmetries of the P300 field (lateralized peaks) reduced the standard amplitude assessment at the midline parletal electrode, but did not Qjfoct the reference-independent, global amplitude assessment. This shows thal asymmetry per se does not imply reduced field strength. in addition, in schizophreraics. but not in controls, there was a significcmt effect oftlae direction of asymmetry on both amplltude measures, amplitudes belng lower with increasing shift ofthe P300 peak to the right side. Considering also the slightly left-lateralized peaks in the normal controls. this suggests rhat only right lateralized P300 peaks upressfunctional deficits in schizophrenics, whereas left lateralized pealcs fall wlthin the physiological variability of the P3OO field. Tht refonnce-independent amplitude assessment is proposed for unambiguous amplitude assessment in order to better define the clinical, psychological and physiopathological mtaning of the P3OO alterations in schizophrenics.}, subject = {Schizophrenie}, language = {en} } @misc{FazelRezaiAllisonGugeretal.2012, author = {Fazel-Rezai, Reza and Allison, Brendan Z. and Guger, Christoph and Sellers, Eric W. and Kleih, Sonja C. and K{\"u}bler, Andrea}, title = {P300 brain computer interface: current challenges and emerging trends}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75941}, year = {2012}, abstract = {A brain-computer interface (BCI) enables communication without movement based on brain signals measured with electroencephalography (EEG). BCIs usually rely on one of three types of signals: the P300 and other components of the event-related potential (ERP), steady state visual evoked potential (SSVEP), or event related desynchronization (ERD). Although P300 BCIs were introduced over twenty years ago, the past few years have seen a strong increase in P300 BCI research. This closed-loop BCI approach relies on the P300 and other components of the ERP, based on an oddball paradigm presented to the subject. In this paper, we overview the current status of P300 BCI technology, and then discuss new directions: paradigms for eliciting P300s; signal processing methods; applications; and hybrid BCIs. We conclude that P300 BCIs are quite promising, as several emerging directions have not yet been fully explored and could lead to improvements in bit rate, reliability, usability, and flexibility.}, subject = {Psychologie}, language = {en} } @phdthesis{Waetzig2011, author = {W{\"a}tzig, Andrea}, title = {Neurophysiologische Evidenz f{\"u}r eine St{\"o}rung des impliziten Ged{\"a}chtnis bei Alkoholabh{\"a}ngigkeit}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56769}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Im Rahmen der vorliegenden Arbeit wurden 21 reine Alkoholpatienten, 6 polytoxikomane Alkoholpatienten und 18 gesunde Kontrollen neurophysiologisch untersucht. Basierend auf einem Paradigma zu Negativem Priming wurden Unterschiede zwischen den genannten Kollektiven bez{\"u}glich der Amplitude und Latenz der P300 im EEG untersucht. Kontrollpersonen zeigten in dieser Studie generell eine signifikant k{\"u}rzere Latenz der P3a als beide Patientenkollektive, was als Hinweis auf eine kognitive Ineffizienz bei Alkoholpatienten gesehen werden kann. Dar{\"u}ber hinaus konnte gezeigt werden, dass reine Alkoholpatienten und polytoxikomane Alkoholpatienten bez{\"u}glich der Ver{\"a}nderungen der P300 getrennt betrachtet werden m{\"u}ssen, da sich signifikante Unterschiede bez{\"u}glich Latenz und Amplitude zwischen den beiden Patientenkollektiven zeigten. Ebenso gibt es Hinweise darauf, dass bei Studien zur P300 Geschlechterunterschiede ber{\"u}cksichtigt werden m{\"u}ssen. Mit vorliegender Studie konnte zudem die Theorie einer prominenten frontocentralen Verteilung der P3a unterst{\"u}tzt werden.}, subject = {Alkoholismus}, language = {de} }