As a noninvasive and safe optical measure of hemodynamic brain activity, near-infrared spectroscopy (NIRS) has emerged as a potential brain-computer interface (BCI) access modality. Currently, to the best of our knowledge, all NIRS BCIs use mental tasks to elicit changes in regional hemodynamic activity. One of the limitations of using mental tasks is that they can be cognitively demanding, and unintuitive. The goal of this work was to explore the development of a neurofeedback-based NIRS BCI that weans users off mental tasks, to instead use voluntary self-regulation. Ten able-bodied participants were recruited for this study. After ten sessions of using two personalized mental tasks to increase and decrease the participant's hemodynamic activity, the users were asked, for the remaining sessions, to stop performing their tasks and instead use only a desire to modulate their hemodynamic activity. By the final online session, participants were able to exclusively use voluntary self-regulation with an average accuracy of 79 ±13%. Additionally, the majority of participants indicated that BCI control via self-regulation was less taxing and more intuitive than BCI operation using mental tasks.

Abstract. Brain-computer interfaces (BCIs) allow individuals to use only cognitive activities to interact with their environment. The widespread use of BCIs is limited, due in part to their lack of user-friendliness. The main goal of this work was to develop a more user-centered BCI and determine if: (1) individuals can acquire control of an online near-infrared spectroscopy BCI via usability and performance-informed selection of mental tasks without compromising classification accuracy and (2) the combination of usability and performance-informed selection of mental tasks yields subjective ease-of-use ratings that exceed those attainable with prescribed mental tasks. Twenty able-bodied participants were recruited. Half of the participants served as a control group, using the state-of-the-art prescribed mental strategies. The other half of the participants comprised the study group, choosing their own personalized mental strategies out of eleven possible tasks. It was concluded that users were, in fact, able to acquire control of the more user-centered BCI without a significant change in accuracy compared to the prescribed task BCI. Furthermore, the personalized BCI yielded higher subjective ease-of-use ratings than the prescribed BCI. Average online accuracies of 77 AE 12.9% and 73 AE 12.9% were achieved by the personalized and prescribed mental task groups, respectively.

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