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Reichert C, Tellez Ceja IF, Sweeney-Reed CM, Heinze HJ, Hinrichs H, Dürschmid S. Impact of Stimulus Features on the Performance of a Gaze-Independent Brain-Computer Interface Based on Covert Spatial Attention Shifts. Front Neurosci 2020; 14:591777. [PMID: 33335470 PMCID: PMC7736242 DOI: 10.3389/fnins.2020.591777] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/10/2020] [Indexed: 11/18/2022] Open
Abstract
Regaining communication abilities in patients who are unable to speak or move is one of the main goals in decoding brain waves for brain-computer interface (BCI) control. Many BCI approaches designed for communication rely on attention to visual stimuli, commonly applying an oddball paradigm, and require both eye movements and adequate visual acuity. These abilities may, however, be absent in patients who depend on BCI communication. We have therefore developed a response-based communication BCI, which is independent of gaze shifts but utilizes covert shifts of attention to the left or right visual field. We recorded the electroencephalogram (EEG) from 29 channels and coregistered the vertical and horizontal electrooculogram. Data-driven decoding of small attention-based differences between the hemispheres, also known as N2pc, was performed using 14 posterior channels, which are expected to reflect correlates of visual spatial attention. Eighteen healthy participants responded to 120 statements by covertly directing attention to one of two colored symbols (green and red crosses for "yes" and "no," respectively), presented in the user's left and right visual field, respectively, while maintaining central gaze fixation. On average across participants, 88.5% (std: 7.8%) of responses were correctly decoded online. In order to investigate the potential influence of stimulus features on accuracy, we presented the symbols with different visual angles, by altering symbol size and eccentricity. The offline analysis revealed that stimulus features have a minimal impact on the controllability of the BCI. Hence, we show with our novel approach that spatial attention to a colored symbol is a robust method with which to control a BCI, which has the potential to support severely paralyzed people with impaired eye movements and low visual acuity in communicating with their environment.
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Affiliation(s)
- Christoph Reichert
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
- Research Campus STIMULATE, Magdeburg, Germany
| | | | - Catherine M. Sweeney-Reed
- Center for Behavioral Brain Sciences, Magdeburg, Germany
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
| | - Hans-Jochen Heinze
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
| | - Hermann Hinrichs
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
- Research Campus STIMULATE, Magdeburg, Germany
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
| | - Stefan Dürschmid
- Department of Behavioral Neurology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany
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Flechsenhar A, Larson O, End A, Gamer M. Investigating overt and covert shifts of attention within social naturalistic scenes. J Vis 2018; 18:11. [PMID: 30458516 DOI: 10.1167/18.12.11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Eye-tracking studies on social attention have consistently shown that humans prefer to attend to other human beings. Much less is known about whether a similar preference is also evident in covert attentional processes. To enable a direct comparison, this study examined covert and overt attentional guidance within two different experimental setups using complex naturalistic scenes instead of isolated single features. In the first experiment, a modified version of the dot-probe paradigm served as a measure of covert reflexive attention toward briefly presented scenes containing a social feature in one half of the visual field compared to nonsocial elements in the other while controlling for low-level visual saliency. Participants showed a stable congruency effect with faster reaction times and fewer errors for probes presented on the social side of the scene. In a second experiment, we tracked eye movements for the same set of stimuli while manipulating the presentation time to allow for differentiating reflexive and more sustained aspects of overt attention. Supportive of the first results, analyses revealed a robust preference for social features concerning initial saccade direction as well as fixation allocation. Collectively, these experiments imply preferential processing of social features over visually salient aspects for automatic allocation of covert as well as overt attention.
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Affiliation(s)
- Aleya Flechsenhar
- Department of Psychology, Julius Maximilians University of Würzburg, Würzburg, Germany
| | - Olivia Larson
- Department of Psychology, McGill University, Montreal, Canada
| | - Albert End
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Matthias Gamer
- Department of Psychology, Julius Maximilians University of Würzburg, Germany.,Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Dreyer AM, Herrmann CS, Rieger JW. Tradeoff between User Experience and BCI Classification Accuracy with Frequency Modulated Steady-State Visual Evoked Potentials. Front Hum Neurosci 2017; 11:391. [PMID: 28798676 PMCID: PMC5526890 DOI: 10.3389/fnhum.2017.00391] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/13/2017] [Indexed: 11/16/2022] Open
Abstract
Steady-state visual evoked potentials (SSVEPs) have been widely employed for the control of brain-computer interfaces (BCIs) because they are very robust, lead to high performance, and allow for a high number of commands. However, such flickering stimuli often also cause user discomfort and fatigue, especially when several light sources are used simultaneously. Different variations of SSVEP driving signals have been proposed to increase user comfort. Here, we investigate the suitability of frequency modulation of a high frequency carrier for SSVEP-BCIs. We compared BCI performance and user experience between frequency modulated (FM) and traditional sinusoidal (SIN) SSVEPs in an offline classification paradigm with four independently flickering light-emitting diodes which were overtly attended (fixated). While classification performance was slightly reduced with the FM stimuli, the user comfort was significantly increased. Comparing the SSVEPs for covert attention to the stimuli (without fixation) was not possible, as no reliable SSVEPs were evoked. Our results reveal that several, simultaneously flickering, light emitting diodes can be used to generate FM-SSVEPs with different frequencies and the resulting occipital electroencephalography (EEG) signals can be classified with high accuracy. While the performance we report could be further improved with adjusted stimuli and algorithms, we argue that the increased comfort is an important result and suggest the use of FM stimuli for future SSVEP-BCI applications.
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Affiliation(s)
- Alexander M Dreyer
- Applied Neurocognitive Psychology Laboratory, Department of Psychology, Center for Excellence "Hearing4all", European Medical School, Carl von Ossietzky UniversityOldenburg, Germany
| | - Christoph S Herrmann
- Experimental Psychology Laboratory, Department of Psychology, Center for Excellence "Hearing4all", European Medical School, Carl von Ossietzky UniversityOldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky UniversityOldenburg, Germany
| | - Jochem W Rieger
- Applied Neurocognitive Psychology Laboratory, Department of Psychology, Center for Excellence "Hearing4all", European Medical School, Carl von Ossietzky UniversityOldenburg, Germany.,Research Center Neurosensory Science, Carl von Ossietzky UniversityOldenburg, Germany
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4
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Immersive BCI with SSVEP in VR head-mounted display. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:1103-6. [PMID: 26736458 DOI: 10.1109/embc.2015.7318558] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this paper we present an immersive brain computer interface (BCI) where we use a virtual reality head-mounted display (VRHMD) to invoke SSVEP responses. Compared to visual stimuli in monitor display, we demonstrate that visual stimuli in VRHMD indeed improve the user engagement for BCI. To this end, we validate our method with experiments on a VR maze game, the goal of which is to guide a ball into the destination in a 2D grid map in a 3D space, successively choosing one of four neighboring cells using SSVEP evoked by visual stimuli on neighboring cells. Experiments indicate that the averaged information transfer rate is improved by 10% for VRHMD, compared to the case in monitor display and the users feel easier to play the game with the proposed system.
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Smith DJ, Varghese LA, Stepp CE, Guenther FH. Comparison of steady-state visual and somatosensory evoked potentials for brain-computer interface control. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:1234-7. [PMID: 25570188 DOI: 10.1109/embc.2014.6943820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Many proposed EEG-based brain-computer interfaces (BCIs) make use of visual stimuli to elicit steady-state visual evoked potentials (SSVEP), the frequency of which can be mapped to a computer input. However, such a control scheme can be ineffective if a user has no motor control over their eyes and cannot direct their gaze towards a flashing stimulus to generate such a signal. Tactile-based methods, such as somatosensory steady-state evoked potentials (SSSEP), are a potentially attractive alternative in these scenarios. Here, we compare the neural signals elicited by SSSEP to those elicited by SSVEP in naïve BCI users towards evaluating the feasibility of SSSEP-based control of an EEG BCI.
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Effects of overt and covert attention on the steady-state visual evoked potential. Neurosci Lett 2012; 519:37-41. [DOI: 10.1016/j.neulet.2012.05.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 04/30/2012] [Accepted: 05/02/2012] [Indexed: 11/30/2022]
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Zhu D, Bieger J, Garcia Molina G, Aarts RM. A survey of stimulation methods used in SSVEP-based BCIs. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2010; 2010:702357. [PMID: 20224799 PMCID: PMC2833411 DOI: 10.1155/2010/702357] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 01/04/2010] [Indexed: 11/24/2022]
Abstract
Brain-computer interface (BCI) systems based on the steady-state visual evoked potential (SSVEP) provide higher information throughput and require shorter training than BCI systems using other brain signals. To elicit an SSVEP, a repetitive visual stimulus (RVS) has to be presented to the user. The RVS can be rendered on a computer screen by alternating graphical patterns, or with external light sources able to emit modulated light. The properties of an RVS (e.g., frequency, color) depend on the rendering device and influence the SSVEP characteristics. This affects the BCI information throughput and the levels of user safety and comfort. Literature on SSVEP-based BCIs does not generally provide reasons for the selection of the used rendering devices or RVS properties. In this paper, we review the literature on SSVEP-based BCIs and comprehensively report on the different RVS choices in terms of rendering devices, properties, and their potential influence on BCI performance, user safety and comfort.
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Affiliation(s)
- Danhua Zhu
- 1Department of Signal Processing Systems, Technical University Eindhoven, 5600 MB Eindhoven, The Netherlands
- 2Department of Brain, Body & Behavior, Philips Research Eindhoven, 5656 AE Eindhoven, The Netherlands
- 3College of Biomedical Engineering and Instrument Science, Zhejiang University, 310027, China
- *Danhua Zhu:
| | - Jordi Bieger
- 2Department of Brain, Body & Behavior, Philips Research Eindhoven, 5656 AE Eindhoven, The Netherlands
- 4Department of Artificial Intelligence, Radboud University Nijmegen, 6500 HE Nijmegen, The Netherlands
| | - Gary Garcia Molina
- 2Department of Brain, Body & Behavior, Philips Research Eindhoven, 5656 AE Eindhoven, The Netherlands
| | - Ronald M. Aarts
- 1Department of Signal Processing Systems, Technical University Eindhoven, 5600 MB Eindhoven, The Netherlands
- 2Department of Brain, Body & Behavior, Philips Research Eindhoven, 5656 AE Eindhoven, The Netherlands
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Mason SG, Bashashati A, Fatourechi M, Navarro KF, Birch GE. A Comprehensive Survey of Brain Interface Technology Designs. Ann Biomed Eng 2006; 35:137-69. [PMID: 17115262 DOI: 10.1007/s10439-006-9170-0] [Citation(s) in RCA: 208] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Accepted: 07/28/2006] [Indexed: 11/24/2022]
Abstract
In this work we present the first comprehensive survey of Brain Interface (BI) technology designs published prior to January 2006. Detailed results from this survey, which was based on the Brain Interface Design Framework proposed by Mason and Birch, are presented and discussed to address the following research questions: (1) which BI technologies are directly comparable, (2) what technology designs exist, (3) which application areas (users, activities and environments) have been targeted in these designs, (4) which design approaches have received little or no research and are possible opportunities for new technology, and (5) how well are designs reported. The results of this work demonstrate that meta-analysis of high-level BI design attributes is possible and informative. The survey also produced a valuable, historical cross-reference where BI technology designers can identify what types of technology have been proposed and by whom.
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Affiliation(s)
- S G Mason
- Neil Squire Society, Brain Interface Laboratory, 220-2250 Boundary Road, Burnaby, Canada V5M 3Z3.
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