International audienceDesigning a feedback that helps participants to achieve higher performances is an important concern in brain-computer interface (BCI) research. In a pilot study, we demonstrate how a congruent auditory feedback could improve classification in a electroencephalography (EEG) motor imagery BCI. This is a promising result for creating alternate feedback modality

Aramaki, Mitsuko

Christophe, Emmanuel

Frey, Jérémy

Kronland-Martinet, Richard

Micoulaud-Franchi, Jean-Arthur

Mladenović , Jelena

Mougin, Gaëlle

Vion-Dury, Jean

Ystad, Sølvi

Mladenović, Jelena

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HAL Id: hal-01794900https://hal.inria.fr/hal-01794900v2Submitted on 21 May 2018HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.L’archive ouverte pluridisciplinaire HAL, estdestinée au dépôt et à la diffusion de documentsscientifiques de niveau recherche, publiés ou non,émanant des établissements d’enseignement et derecherche français ou étrangers, des laboratoirespublics ou privés.Evaluation of a congruent auditory feedback for MotorImagery BCIEmmanuel Christophe, Jérémy Frey, Richard Kronland-Martinet, Jean-ArthurMicoulaud-Franchi, Jelena Mladenović, Gaëlle Mougin, Jean Vion-Dury, SølviYstad, Mitsuko AramakiTo cite this version:Emmanuel Christophe, Jérémy Frey, Richard Kronland-Martinet, Jean-Arthur Micoulaud-Franchi,Jelena Mladenović, et al.. Evaluation of a congruent auditory feedback for Motor Imagery BCI.International BCI meeting, May 2018, Asilomar, United States. ￿hal-01794900v2￿Evaluation of a congruent auditory feedback for MotorImagery BCIEmmanuel Christophe1, Jérémy Frey2, Richard Kronland-Martinet1,Jean-Arthur Micoulaud-Franchi3, Jelena Mladenović4,5, Gaelle Mougin6, Jean Vion-Dury1,Solvi Ystad1, Mitsuko Aramaki11PRISM laboratory, CNRS, Univ. Aix Marseille, France; 2Ullo, La Rochelle, France; 3Clinique du Sommeil, CHU deBordeaux, CNRS, Univ. Bordeaux, France; 4Inria, Bordeaux, France; 5CRNL Inserm, CNRS, Lyon, France; 6ENS,Pays germaniques Archives Husserl,CNRS, Paris, FranceCorrespondence: Jelena Mladenović, Inria, Bordeaux, France. E-mail: jelena.mladenovic@inria.frAbstract. Designing a feedback that helps participants to achieve higher performances is an important concern inbrain-computer interface (BCI) research. In a pilot study, we demonstrate how a congruent auditory feedback couldimprove classification in a electroencephalography (EEG) motor imagery BCI. This is a promising result for creatingalternate feedback modality.Keywords: BCI, EEG, motor imagery, auditory feedback, congruent feedback1 IntroductionDesigning a feedback that helps participants to achieve higher performances is an important concern in brain-computerinterface (BCI) research. Various congruent (task-related) visual feedback have been examined and showed promisingresults, e.g. using body ownership illusions in VR [Alimardani et al., 2014]. The use of congruent sound in com-bination with the visual modality demonstrated to increase performances in Motor Imagery (MI) BCI [Tidoni et al.,2014]. However, evaluating solely auditory feedback is often neglected, even though it could be a valuable alternativemodality. We investigate the relevance of congruent versus non-congruent (abstract) auditory feedback in assisting theuser to imagine feet movement in an EEG-based MI BCI.2 Material, Methods and ResultsUsers task was either to imagine moving their feet or to rest. The instructions consisted of 4-taps of sticks for MIof feet, and a relaxing sound for the resting state (Figure 1 A). There were two conditions: "non-congruent", duringwhich the feedback provided was abstract and not related to any task (harmonic sounds with a different pitch) and"congruent", during which the MI feedback reflected the sound of one’s footsteps on gravel, and the rest feedback arelaxing sound of water. The choice of such sound for the congruent MI task was motivated by the fact that rhythmicalsounds relate to motor cortex [Bengtsson et al., 2009]. For the same reason, both tasks in the non-congruent conditionwere as non-rhythmic as possible. Moreover, such congruent sounds were chosen to increase sense of ownership. Theinfluence of the feedback was evaluated within-subjects.Non-congruent and congruent feedback were generated in real-time, the former with Max-MSP and the latter witha dedicated synthesizer of environmental sounds [Verron et al., 2010].Ten participants were recruited (2 women, mean age: 24.8, SD: 4.98, all BCI naives). They were seated in frontof a single speaker. 7 passive gold cup electrodes were placed over Cz, C1, C2, FCz, CPz, CP1 and CP2 in the10-20 system and connected to an OpenBCI Cyton amplifier. Before the experiment participants heard an exampleof each sound to get accustomed to the task. In order not to reveal the outcome of the experiment, the feedback wassimply introduced as “environmental sounds” or “musical sounds”. A run of calibration was followed by two runswith one feedback and then two runs with the other (conditions’ order was counterbalanced across participants). Arun contained 30 trials of 13 seconds, 15 for each class (rest or MI) in random order. A session lasted ≈45m.Using OpenViBE, signals were filtered in the alpha (8-13 Hz) and beta (13-30 Hz) bands, passed to a FilterBank Common Spatial Pattern filter and classified using linear discriminant analysis. We tested for significance usingWilcoxon signed-rank tests. There was no difference in online performance between the two feedback (Figure 1 B).An offline analysis revealed a significant difference (p < 0.05) in classification accuracy when a classifier was trainedseparately on the "congruent" and "non-congruent" runs (respectively 66.1%, SD: 7.45 and 63.9% SD: 7.8, 10-fold7th International BCI Meeting, May 21-15, 2018 1cross-validation, Figure 1 C). There were also changes in EEG spectral power, with more activation in the "congruent"condition within the beta band during rest and within both alpha and beta bands during MI (Figure 1 D and 1 E).CBD EA*n.s.Figure 1: Comparison between congruent and non-congruent audio feedback during a motor imagery BCI (feet imagination vsrest). A: Audio sequence for one trial. B: Peak performance of the online classifier. C: Accuracy of a classifier trained offline oneach conditon. D and E: spectral power analysis per elecrtode, during feet and rest trials respectively (significant differences arehighlighted, p < 0.05).7th International BCI Meeting, May 21-15, 2018 23 DiscussionWhile the online performance remained unchanged with a congruent feedback, an offline classifier could benefit fromincreased differences between rest and MI signals. Additionally, post-hoc interviews revealed that participants feltassisted by a congruent feedback.4 SignificanceIn a pilot study, we demonstrate how a congruent auditory feedback could improve classification in a EEG MI BCI, apromising result for creating alternate feedback modality. This prompts for further investigations on a larger sampleand with more channels to better assess the underlying change in brain activity.ReferencesAlimardani, M., Nishio, S., and Ishiguro, H. (2014). Effect of biased feedback on motor imagery learning in bci-teleoperation system. Frontiers in systems neuroscience, 8:52.Bengtsson, S. L., Ullen, F., Ehrsson, H. H., Hashimoto, T., Kito, T., Naito, E., Forssberg, H., and Sadato, N. (2009).Listening to rhythms activates motor and premotor cortices. cortex, 45(1):62–71.Tidoni, E., Gergondet, P., Kheddar, A., and Aglioti, S. M. (2014). Audio-visual feedback improves the bci performancein the navigational control of a humanoid robot. Frontiers in neurorobotics, 8:20.Verron, C., Aramaki, M., Kronland-Martinet, R., and Pallone, G. (2010). A 3-d immersive synthesizer for environ-mental sounds. IEEE Transactions on Audio, Speech, and Language Processing, 18(6):1550–1561.7th International BCI Meeting, May 21-15, 2018 3

Evaluation of a congruent auditory feedback for Motor Imagery BCI

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Evaluation of a congruent auditory feedback for Motor Imagery BCI

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