Towards a system-paced near-infrared spectroscopy brain–computer interface: differentiating prefrontal activity due to mental arithmetic and mental singing from the no-control state

Abstract

Near-infrared spectroscopy (NIRS) has recently been investigated as a non-invasive brain-computer interface (BCI) for individuals with severe motor impairments. For the most part, previous research has investigated the development of NIRS-BCIs operating under synchronous control paradigms, which require the user to exert conscious control over their mental activity whenever the system is vigilant. Though functional, this is mentally demanding and an unnatural way to communicate. An attractive alternative to the synchronous control paradigm is system-paced control, in which users are required to consciously modify their brain activity only when they wish to affect the BCI output, and can remain in a more natural, 'no-control' state at all other times. In this study, we investigated the feasibility of a system-paced NIRS-BCI with one intentional control (IC) state corresponding to the performance of either mental arithmetic or mental singing. In particular, this involved determining if these tasks could be distinguished, individually, from the unconstrained 'no-control' state. Deploying a dual-wavelength frequency domain near-infrared spectrometer, we interrogated nine sites around the frontopolar locations (International 10-20 System) while eight able-bodied adults performed mental arithmetic and mental singing to answer multiple-choice questions within a system-paced paradigm. With a linear classifier trained on a six-dimensional feature set, an overall classification accuracy of 71.2% across participants was achieved for the mental arithmetic versus no-control classification problem. While the mental singing versus no-control classification was less successful across participants (62.7% on average), four participants did attain accuracies well in excess of chance, three of which were above 70%. Analyses were performed offline. Collectively, these results are encouraging, and demonstrate the potential of a system-paced NIRS-BCI with one IC state corresponding to either mental arithmetic or mental singing.

Mental stress assessment using simultaneous measurement of EEG and fNIRS

“…In contrast, features from fNIRS were classified with 84.15 ± 6.8, 82.4% ± 6.3 and 86% ± 7.2 accuracy, sensitivity and specificity respectively. These fNIRS results outperformed previous studies [47,[88][89][90][91][92][93][94][95][96][97][98]. It however needs to be cautious as the data sets were different.…”

Evaluating a four-class motor-imagery-based optical brain-computer interface

“…Functional near infrared spectroscopy (fNIRS) is a noninvasive optical brain imaging technique that has shown promise for future BCI applications [2]- [6], including the detection of motor movements [7]- [9]. It has also been used alongside bio-signals [10] and to augment existing EEG BCIs [11].…”

Usability and performance-informed selection of personalized mental tasks for an online near-infrared spectroscopy brain-computer interface

“…14,54,55 Several other NIRS-BCI studies have also used a source-detector separation distance of 3 cm over the PFC. 9,14,[23][24][25]27 The source-detector configuration allowed for the interrogation of nine discrete locations. A schematic diagram of the configuration and points of interrogation is shown in Fig.…”

“…By discriminating between the changes in the NIRS signal resulting from the user performing each task, one is able to control the binary BCI. Several different mental tasks have been used in past NIRS-BCI studies, including mental math, 2,9,14,[22][23][24][25][26][27][28][29] mental singing, 9,23,24 word generation, 22,26,28 memory, 6,26,28 mental counting, 30 mental rotation, 22 concentration, 31 motor imagery, 3,8,10,32,33 and rest.…”

“…This task has been used in several previous NIRS-BCI studies. 2,9,14,[22][23][24][25][26][27][28][29]56,57 Mental singing (Music) Participants were asked to sing a song in their head. They were informed they could choose to sing any song they wanted, but they were asked to pick a song that they liked.…”