Long Multi-Stage Training for a Motor-Impaired User in a BCI Competition

Abstract

In a Mental Imagery Brain-Computer Interface the user has to perform a specific mental task that generates electroencephalography (EEG) components, which can be translated in commands to control a BCI system. The development of a high-performance MI-BCI requires a long training, lasting several weeks or months, in order to improve the ability of the user to manage his/her mental tasks. This works aims to present the design of a MI-BCI combining mental imaginary and cognitive tasks for a severely motor impaired user, involved in the BCI race of the Cybathlon event, a competition of people with severe motor disability. In the BCI-race, the user becomes a pilot in a virtual race game against up to three other pilots, in which each pilot has to control his/her virtual car by his/her mental tasks. We present all the procedures followed to realize an effective MI-BCI, from the user's first contact with a BCI technology to actually controlling a video-game through her EEG. We defined a multi-stage user-centered training protocol in order to successfully control a BCI, even in a stressful situation, such as that of a competition. We put a specific focus on the human aspects that influenced the long training phase of the system and the participation to the competition.

Competing at the Cybathlon Championship for Athletes With Disabilities: Long-Term Motor Imagery Brain-Computer Interface Training of a Tetraplegic Cybathlete

“…Our results show that decoding accuracy increased during the online sessions following the calibration period. This observation is in line with similar studies that have demonstrated improvements in the Cybathlon pilot's BCI control ability due to long-term practice periods -although this has not always translated into high performance on the day of the event, as was the case with the current study and for both [14] and [15]. Possible reasons for this drop in race-day performance, and suggested strategies to address the issue are discussed.…”

“…Performance accuracy improved by 30% over a three-month training period (20 sessions) -although the user's competition day performance did not re ect this improvement. A similar drop in performance during the Cybathlon competition game, compared to performance during training, has been reported by Turi et al in [15]. They suggested that the drop was due to the indirect impact of stress on performance -expressly the user's psychological state in uenced their ability to concentrate, which affected their performance negatively.…”

“…The best three ranked teams completed the track in the nal challenge of the Cybathlon BCI series (2019) in the following order. Rank 1st : WHI team (500m within 183s), Rank 2nd : Mirage 91 team (500m within 229s), Rank 3rd : NeuroCONCISE team (386m within the 240s limit) [30], [15]. The best three ranked teams in the Cybathlon Global Edition (2020) completed the track in the following order.…”

“…However, their pilot could not nish the track within the 4 minutes limit. For the NITRO 2 team, Turi et al reported in the nal competition of the Cybathlon BCI series (2019) their pilot completed a 390.5m disrtance in the 500m long vitual track within the 240s limit [15] but did not note details of the game completion time achieved by their pilot during the training period. For the Mirage 91 team, Hehenberger et al reported that their pilot's performance showed a constant improvement over 14 months of training including 26 game-based sessions for the Cybathlon BCI series (2019) and Cybathlon Global Edition (2020) [28].…”

“…However, they also report that they were not able to translate this to event day performances, which is consistent with our ndings. Additionally, Turi et al reported a similar outcome for competition day results, citing multivariate factors that in uence and potentially disrupt pilot performance, including training time, change in routine, differences in the training method with the nal game, and differences in training and event environment [15]. A longitudinal study involving another Cybathlon tetraplegic pilot [29] nal race [28].…”