Abstract
For BCI systems, it is important to have an accurate and less complex architecture to control a device with enhanced accuracy. In this paper, a novel methodology for more accurate detection of the hemodynamic response has been developed using a multimodal brain-computer interface (BCI). An integrated classifier has been developed for achieving better classification accuracy using two modalities. An integrated EEG-fNIRS-based vector-phase analysis (VPA) has been conducted. An open-source dataset collected at the Technische Universität Berlin, including simultaneous electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) signals of 26 healthy participants during n-back tests, has been used for this research. Instrumental and physiological noise removal has been done using preprocessing techniques followed by individually detecting activity in both modalities. With resting state threshold circle, VPA has been used to detect a hemodynamic response in fNIRS signals, whereas phase plots for EEG signals have been constructed using Hilbert Transform to detect the activity in each trial. Multiple threshold circles are drawn in the vector plane, where each circle is drawn after task completion in each trial of EEG signal. Finally, both processes are integrated into one vector-phase plot to get combined detection of hemodynamic response for activity. Results of this study illustrate that the combined EEG-fNIRS VPA yields considerably higher average classification accuracy, that is 91.35%, as compared to other classifiers such as support vector machine (SVM), convolutional neural networks (CNN), deep neural networks (DNN) and VPA (with dual-threshold circles) with classification accuracies 82%, 89%, 87% and 86% respectively. Outcomes of this research demonstrate that improved classification performance can be feasibly achieved using multimodal VPA for EEG-fNIRS hybrid data.
Highlights
A brain-computer interface (BCI) is a pathway for communication between brain thoughts and computer to achieve hardware control, without any dependence on channels like nerves and muscles. [1,2]
We propose a novel modified multimodal vector-phase analysis (VPA) methodology to detect activity in hemodynamic response
Phase plot for the average activity signal was constructed and compared with the phase plot of the rest signal. It can be seen from the simultaneous phase plot of activity and rest, in Fig. 9, that the activity is contained in the right side of the plane, indicating the x-coordinate of its centre value as greater than 0
Summary
A brain-computer interface (BCI) is a pathway for communication between brain thoughts and computer to achieve hardware control, without any dependence on channels like nerves and muscles. [1,2]. A brain-computer interface (BCI) is a pathway for communication between brain thoughts and computer to achieve hardware control, without any dependence on channels like nerves and muscles. The main purpose of a BCI is to equip physically impaired people, especially with motor disabilities, with the facility to communicate with the help of their brain signals [3,4]. A BCI is used to detect and interpret brain signals to control the devices [5]. A BCI helps users develop an interface between their brain and peripheral devices without any kind of physical movement [6,7,8,9]. Various assistive rehabilitative devices have been controlled using different types of BCI systems [11], such as electroencephalography (EEG) [12,13] and functional near-infrared spectroscopy (fNIRS) [14,15] etc
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