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Improving BCI decoding performance through analysis of cortical traveling waves

Kevin Vanbecelaere1*, Nikolay Chumerin2, Cees Van Leeuwen1 and David M. Alexander1
  • 1 KU Leuven, Belgium
  • 2 KU Leuven, Belgium

An assumption in nearly all cognitive neuroscience research is that of space-time separability. It assumes that the mechanisms constituting the cortical signal are functions of space and time, and that these dimensions of signal can be treated separately. This implies that part of the signal -that which is space-time inseparable- is noise. A growing literature focuses on the spatiotemporal dynamics of cortical activity in the form of traveling waves. Traveling waves have been shown to be functionally significant at the single-trial level (Alexander et al., 2006; Alexander et al., 2009) and at multiple spatial scales of cortex (Klimesch et al., 2007; Nauhaus et al., 2009; Takahashi et al., 2011). The steady-state visual evoked potential (SSVEP) data presented in this paper come from a brain-computer interface (BCI) setup. The aim of a BCI system is to decode brain activity in order to enable subjects to interact with the world through computers, bypassing the need of muscular activity. Participants were shown three aligned LED stimuli flickering at different frequencies and at different phase shifts. When flickering in the alpha band, the stimulus induces an EEG response that possesses a spectral component narrowly centered around the frequency of presentation. The BCI apparatus uses this response to decide what stimulus the subject is looking at. Therefore, maximizing the phase accuracy of the stimulus-induced SSVEP signal is crucial for efficient decoding. Typically, phase-locking to the mean phase of the stimulus is relatively poor (i.e. circular variance relatively large). In this paper, we hypothesize that the BCI signal is not space-time separable and much of phase jitter can be explained by taking traveling wave components into account, hence improving the BCI performance.

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References

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Klimesch, W., Hanslmayr, S., Sauseng, P., Gruber, W. R., & Doppelmayr, M. (2007). P1 and traveling alpha waves: evidence for evoked oscillations. Journal of Neurophysiology, 97(2), 1311–1318. doi:10.1152/jn.00876.2006

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Keywords: traveling waves, BCI, SSVEP, Space-time separability, EEG

Conference: Second Belgian Neuroinformatics Congress, Leuven, Belgium, 4 Dec - 4 Dec, 2015.

Presentation Type: Poster Presentation

Topic: Methods and Modeling

Citation: Vanbecelaere K, Chumerin N, Van Leeuwen C and Alexander DM (2015). Improving BCI decoding performance through analysis of cortical traveling waves. Front. Neuroinform. Conference Abstract: Second Belgian Neuroinformatics Congress. doi: 10.3389/conf.fninf.2015.19.00038

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Received: 16 Oct 2015; Published Online: 17 Nov 2015.

* Correspondence: Mr. Kevin Vanbecelaere, KU Leuven, B- 3000, Vlaams-Brabant, Leuven, Belgium, kevin.vanbecelaere@ppw.kuleuven.be