Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components

Müller-Putz, Gernot; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert

doi:10.1088/1741-2560/2/4/008

Cited by 463 publications

(271 citation statements)

References 19 publications

Supporting

Mentioning

257

Contrasting

Unclassified

Order By: Relevance

“…Figure 5 shows that the same frequencies that other subjects might use for control, 10 or 12 Hz, would not have allowed this subject to control a BCI. While other BCI studies have also reported that subjects may show stronger activity over the first, second, or even third harmonic (Gao et al, 2003;Müller-Putz et al, 2005), it is unclear whether this difference occurs due to natural variation among subjects, display and task parameters, different attentional strategies, or other factors.…”

Section: : Inter-subject Differences and Implications For Bcismentioning

confidence: 95%

“…They can exhibit good information throughput relative to other BCIs (Sutter, 1992;Cheng et al, 2002;Gao et al, 2003;Müller-Putz et al, 2005). They can operate in challenging environments with uncontrolled distraction and electrical noise (Cheng et al, 2002;Wang et al, 2004;Trejo et al, 2006) and hence could work well in homes or hospital settings.…”

Section: : Future Directions With Ssvep Bcismentioning

confidence: 99%

“…Many avenues toward improvement that have been successful with other BCIs, such as improved referencing, filtering, subject and classifier training, task and display optimization, noise rejection, incorporation of additional signal features, spectral analysis parameters, and other parameters have not yet been fully explored (McFarland et al, 1997(McFarland et al, , 1998(McFarland et al, , 2005(McFarland et al, , 2006Wolpaw et al, 2002;Allison, 2003;Birbaumer et al, 2003;Kübler and Neumann, 2005;Neuper et al, 2005;Allison and Pineda, 2006). Initial efforts have suggested that some of these avenues may be useful in SSVEP BCI systems (Wang et al, 2004;Kelly et al, 2005aKelly et al, , 2005bLalor et al, 2005;Müller-Putz et al, 2005;Trejo et al, 2006). Dependence on muscle control is best regarded as a facet of individual BCIs, rather than a whole category of them.…”

Section: : Future Directions With Ssvep Bcismentioning

confidence: 99%

See 2 more Smart Citations

Towards an independent brain–computer interface using steady state visual evoked potentials

Allison

McFarland

Schalk

et al. 2008

Clinical Neurophysiology

285

183

View full text Add to dashboard Cite

Objective-Brain -computer interface (BCI) systems using steady state visual evoked potentials (SSVEPs) have allowed healthy subjects to communicate. However, these systems may not work in severely disabled users because they may depend on gaze shifting. This study evaluates the hypothesis that overlapping stimuli can evoke changes in SSVEP activity sufficient to control a BCI. This would provide evidence that SSVEP BCIs could be used without shifting gaze.Methods-Subjects viewed a display containing two images that each oscillated at a different frequency. Different conditions used overlapping or non-overlapping images to explore dependence on gaze function. Subjects were asked to direct attention to one or the other of these images during each of twelve one-minute runs.Results-Half of the subjects produced differences in SSVEP activity elicited by overlapping stimuli that could support BCI control. In all remaining users, differences did exist at corresponding frequencies but were not strong enough to allow effective control.Conclusions-The data demonstrate that SSVEP differences sufficient for BCI control may be elicited by selective attention to one of two overlapping stimuli. Thus, some SSVEP-based BCI approaches may not depend on gaze control. The nature and extent of any BCI's dependence on muscle activity is a function of many factors, including the display, task, environment, and user.Significance-SSVEP BCIs might function in severely disabled users unable to reliably control gaze. Further research with these users is necessary to explore the optimal parameters of such a system and validate online performance in a home environment.

show abstract

Section: : Inter-subject Differences and Implications For Bcismentioning

confidence: 95%

Section: : Future Directions With Ssvep Bcismentioning

confidence: 99%

Section: : Future Directions With Ssvep Bcismentioning

confidence: 99%

See 1 more Smart Citation

Towards an independent brain–computer interface using steady state visual evoked potentials

Allison

McFarland

Schalk

et al. 2008

Clinical Neurophysiology

285

183

View full text Add to dashboard Cite

show abstract

“…Current BCIs relying on VEPs depend on gaze control [16,17] and thus fall into the category of dependent BCIs [1]. Therefore, these BCIs are not applicable to those whose severe disabilities extend to impaired or nonexistent ocular motor control, such as LIS patients in which (i) eye movements may be inconsistent, very small and easily exhausted in the acute stage and (ii) deteriorated or nonexistent oculomotor control could be observed in the chronic stage.…”

Section: Introductionmentioning

confidence: 99%

An independent SSVEP-based brain–computer interface in locked-in syndrome

et al. 2014

View full text Add to dashboard Cite

Objective. Steady-state visually evoked potential (SSVEP)-based brain-computer interfaces (BCIs) allow healthy subjects to communicate. However, their dependence on gaze control prevents their use with severely disabled patients. Gaze-independent SSVEP-BCIs have been designed but have shown a drop in accuracy and have not been tested in brain-injured patients. In the present paper, we propose a novel independent SSVEP-BCI based on covert attention with an improved classification rate. We study the influence of feature extraction algorithms and the number of harmonics. Finally, we test online communication on healthy volunteers and patients with locked-in syndrome (LIS). Approach. Twenty-four healthy subjects and six LIS patients participated in this study. An independent covert two-class SSVEP paradigm was used with a newly developed portable light emitting diode-based 'interlaced squares' stimulation pattern. Main results. Mean offline and online accuracies on healthy subjects were respectively 85 ± 2% and 74 ± 13%, with eight out of twelve subjects succeeding to communicate efficiently with 80 ± 9% accuracy. Two out of six LIS patients reached an offline accuracy above the chance level, illustrating a response to a command. One out of four LIS patients could communicate online. Significance. We have demonstrated the feasibility of online communication with a covert SSVEP paradigm that is truly independent of all neuromuscular functions. The potential clinical use of the presented BCI system as a diagnostic (i.e., detecting command-following) and communication tool for severely brain-injured patients will need to be further explored.

show abstract

“…Ces avantages rendent la méthode particulièrement appropriée pour détecter la capacité de réponse à une commande au chevet de patients cérébrolésés, ces derniers présentant fré-quemment des mouvements involontaires (à l'origine de nombreux artefacts de mouvement) et pouvant difficilement s'entraîner durant plusieurs jours en raison de leur fatigabilité et des fluctuations de leur vigilance. Toutefois, les SSVEP-BCI dépendent généralement des canaux standard de communication que sont les nerfs périphériques et les muscles : le sujet doit disposer du contrôle de ses yeux afin de fixer directement du regard un des stimulus présentés dans son champ visuel en réponse à l'instruction (attention explicite, de l'anglais overt attention) [23]. Cette exigence ne pose aucun problème pour des sujets sains, mais limite fortement l'application de l'interface chez des patients dont le handicap moteur s'étend au contrôle oculaire (altéré ou inexistant).…”

Section: Vers Un Paradigme Visuel Indépendantunclassified