A Between-Subject fNIRS-BCI Study on Detecting Self-Regulated Intention During Walking

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 28; no. 2; pp. 531 - 540
• Main Authors: Li, Chunguang, Su, Min, Xu, Jiacheng, Jin, Hedian, Sun, Lining
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.02.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptability; Algorithms; Area Under Curve; Brain; Brain-computer interface; Brain-Computer Interfaces; Computational modeling; Computer applications; Decision Trees; Decoding; Dynamics; ensemble learning; Entropy; False Positive Reactions; Female; functional near infrared spectroscopy; Gait; Genetic algorithms; Healthy Volunteers; Hemoglobin; Human-computer interface; Humans; Implants; Infrared spectroscopy; Intention; Latency; Legged locomotion; Male; Mathematical morphology; Model accuracy; Motion perception; Near infrared radiation; Recognition; Reduction; Reproducibility of Results; self-regulated intention; Spectroscopy; Spectroscopy, Near-Infrared - methods; Support Vector Machine; Support vector machines; Task analysis; Technology; Test procedures; Walking; Walking - psychology; Young Adult
• ISSN: 1534-4320; 1558-0210; 1558-0210
• DOI: 10.1109/TNSRE.2020.2965628

Objective: Most BCI (brain-computer interface) studies have focused on detecting motion intention from a resting state. However, the dynamic regulation of two motion states, which usually happens in real life, is rarely studied. Besides, popular within-subject methods also require an extensive and time-consuming learning stage when testing on a new subject. This paper proposed a method to discriminate dynamic gait- adjustment intention with strong adaptability for different subjects. Methods: Cerebral hemoglobin signals obtained from 30 subjects were studied to decode gait-adjustment intention. Cerebral hemoglobin information was recorded by using fNIRS (functional near infrared spectroscopy) technology. Mathematical morphology filtering was applied to remove zero drift and EWM (Entropy Weight Method) was used to calculate the average hemoglobin values over Regions of Interest (ROIs). The gradient boosting decision tree (GBDT) was utilized to detect the onset of self-regulated intention. A 2-layer-GA-SVM (Genetic Algorithm-Support Vector Machine) model based on stacking algorithm was further proposed to identify the four types of self-regulated intention (speed increase, speed reduction, step increase, and step reduction). Results: It was found that GBDT had a good performance to detect the onset intention with an average AUC (Area Under Curve) of 0.894. The 2-layer-GA-SVM model boosted the average ACC (accuracy) of four types of intention from 70.6% to 84.4% ({p} =0.005 ) from the single GA-SVM model. Furthermore, the proposed method passed pseudo-online test with the average results as following: AUC = 0.883, TPR (True Positive Rate) = 97.5%, FPR (False Positive Rate) = 0.11%, and LAY (Detection Latency) = -0.52 ± 2.57 seconds for the recognition of gait-adjustment intention; ACC = 80% for the recognition of adjusted gait. Conclusion: The results indicate that it is feasible to decode dynamic gait-adjustment intentions from a motion state for different subjects based on fNIRS technology. It has a potential to realize the practical application of fNIRS-based brain-computer interface technology in controlling walking-assistive devices.