title: A Sliced Inverse Regression (SIR) Decoding the Forelimb Movement from Neuronal Spikes in the Rat Motor Cortex.
abstract: Several neural decoding algorithms have successfully converted brain signals into commands to control a computer cursor and prosthetic devices. A majority of decoding methods, such as population vector algorithms (PVA), optimal linear estimators (OLE), and neural networks (NN), are effective in predicting movement kinematics, including movement direction, speed and trajectory but usually require a large number of neurons to achieve desirable performance. This study proposed a novel decoding algorithm even with signals obtained from a smaller numbers of neurons. We adopted sliced inverse regression (SIR) to predict forelimb movement from single-unit activities recorded in the rat primary motor (M1) cortex in a water-reward lever-pressing task. SIR performed weighted principal component analysis (PCA) to achieve effective dimension reduction for nonlinear regression. To demonstrate the decoding performance, SIR was compared to PVA, OLE, and NN. Furthermore, PCA and sequential feature selection (SFS) which are popular feature selection techniques were implemented for comparison of feature selection effectiveness. Among SIR, PVA, OLE, PCA, SFS, and NN decoding methods, the trajectories predicted by SIR (with a root mean square error, RMSE, of 8.47 ± 1.32 mm) was closer to the actual trajectories compared with those predicted by PVA (30.41 ± 11.73 mm), OLE (20.17 ± 6.43 mm), PCA (19.13 ± 0.75 mm), SFS (22.75 ± 2.01 mm), and NN (16.75 ± 2.02 mm). The superiority of SIR was most obvious when the sample size of neurons was small. We concluded that SIR sorted the input data to obtain the effective transform matrices for movement prediction, making it a robust decoding method for conditions with sparse neuronal information.
authors.affiliation: Department of Mechanical and Computer Aided Engineering, Feng Chia University Taichung, Taiwan.
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan.
authors.forename: You-Yin
authors.initials: YY
authors.lastname: Chen
authors.affiliation: Institute of Biomedical Engineering, College of Medicine, National Taiwan UniversityTaipei, Taiwan; Department of Neurology, Tzu Chi General HospitalTzu Chi University, Hualien, Taiwan.
authors.forename: Sheng-Huang
authors.initials: SH
authors.lastname: Lin
authors.affiliation: Institute of Biomedical Engineering and Nanomedicine, National Health Research InstitutesZhunan Township, Taiwan; Singapore Institute for Neurotechnology, National University of SingaporeSingapore, Singapore.
authors.forename: Lun-De
authors.initials: LD
authors.lastname: Liao
authors.affiliation: Institute of Statistics, National Chiao Tung University Hsinchu, Taiwan.
authors.forename: Henry Horng-Shing
authors.initials: HH
authors.lastname: Lu
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan.
authors.forename: Ching-Fu
authors.initials: CF
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, National Yang Ming University Taipei, Taiwan.
authors.forename: Po-Chuan
authors.initials: PC
authors.lastname: Chen
authors.affiliation: The Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University Taipei, Taiwan.
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lo
authors.affiliation: Department of Mechanical and Computer Aided Engineering, Feng Chia University Taichung, Taiwan.
authors.forename: Thanh Dat
authors.initials: TD
authors.lastname: Phan
authors.affiliation: Department of Electrical Engineering, National Taiwan University Taipei, Taiwan.
authors.forename: Hsiang-Ya
authors.initials: HY
authors.lastname: Chao
authors.affiliation: Department and Institute of Physiology, School of Medicine, National Yang Ming University Taipei, Taiwan.
authors.forename: Hui-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies, Zhejiang University Hangzhou, China.
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Lai
authors.affiliation: Department of Materials Science and Engineering, Carnegie Mellon University Pittsburgh, PA, USA.
authors.forename: Wei-Chen
authors.initials: WC
authors.lastname: Huang
keywords: forelimb movement prediction; neural decoding; neural networks (NN); principle component analysis (PCA); sliced inverse regression (SIR)