Abstract
This study investigated the effectiveness of using a high-density multi-distance source-detector (SD) separations in near-infrared spectroscopy (NIRS), for enhancing the performance of a functional NIRS (fNIRS)-based brain-computer interface (BCI). The NIRS system that was used for the experiment was capable of measuring signals from four SD separations: 15, 21.2, 30, and 33.5 mm, and this allowed the measurement of hemodynamic response alterations at various depths. Fifteen participants were asked to perform mental arithmetic and word chain tasks, to induce task-related hemodynamic response variations, or they were asked to stay relaxed to acquire a baseline signal. To evaluate the degree of BCI performance enhancement by high-density channel configuration, the classification accuracy obtained using a typical low-density lattice SD arrangement, was compared to that obtained using the high-density SD arrangement, while maintaining the SD separation at 30 mm. The analysis results demonstrated that the use of a high-density channel configuration did not result in a noticeable enhancement of classification accuracy. However, the combination of hemodynamic variations, measured by two multi-distance SD separations, resulted in the significant enhancement of overall classification accuracy. The results of this study indicated that the use of high-density multi-distance SD separations can likely provide a new method for enhancing the performance of an fNIRS-BCI.
Highlights
Near-infrared spectroscopy (NIRS) is becoming a highly popular modality for implementing brain-computer interfaces (BCIs), due to its safety, portability, and high reliability[1]
Among the various mental tasks adopted for these functional NIRS (fNIRS)-BCIs, the mental arithmetic (MA) task has been widely used because users find it intuitive, and because it demonstrates high reproducibility in terms of induced prefrontal cortex (PFC) activations[5,6,7,8,9,10,11,12]
We investigated whether the use of near-infrared spectroscopy (NIRS), with high-density multi-distance SD separations for fNIRS-BCI, could result in enhanced BCI performance
Summary
Near-infrared spectroscopy (NIRS) is becoming a highly popular modality for implementing brain-computer interfaces (BCIs), due to its safety, portability, and high reliability[1]. As the intensity of the light incident on the brain is severely influenced by hair covering the motor-related areas, time-consuming preparatory work is required to prevent the attenuation of light intensity To avoid this inconvenience, BCI paradigms using the hemodynamic variations of the prefrontal cortex (PFC), which is not covered with hair, have been actively studied. There has been no study on whether the new type of NIRS device, with high-density multi-distance SD separations, could result in enhanced BCI performance, and in terms of classification accuracy. To the best of our knowledge, this is the first study to investigate the effectiveness of using high-density multi-distance SD separations to record hemodynamic responses in the PFC, for enhancing the performance of an fNIRS-BCI
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