1
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Toktas A, Erkan U, Ustun D, Wang X. Parameter optimization of chaotic system using Pareto-based triple objective artificial bee colony algorithm. Neural Comput Appl 2023. [DOI: 10.1007/s00521-023-08434-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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2
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Asanza V, Peláez E, Loayza F, Lorente-Leyva LL, Peluffo-Ordóñez DH. Identification of Lower-Limb Motor Tasks via Brain-Computer Interfaces: A Topical Overview. SENSORS (BASEL, SWITZERLAND) 2022; 22:2028. [PMID: 35271175 PMCID: PMC8914806 DOI: 10.3390/s22052028] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/11/2022] [Accepted: 02/23/2022] [Indexed: 02/01/2023]
Abstract
Recent engineering and neuroscience applications have led to the development of brain-computer interface (BCI) systems that improve the quality of life of people with motor disabilities. In the same area, a significant number of studies have been conducted in identifying or classifying upper-limb movement intentions. On the contrary, few works have been concerned with movement intention identification for lower limbs. Notwithstanding, lower-limb neurorehabilitation is a major topic in medical settings, as some people suffer from mobility problems in their lower limbs, such as those diagnosed with neurodegenerative disorders, such as multiple sclerosis, and people with hemiplegia or quadriplegia. Particularly, the conventional pattern recognition (PR) systems are one of the most suitable computational tools for electroencephalography (EEG) signal analysis as the explicit knowledge of the features involved in the PR process itself is crucial for both improving signal classification performance and providing more interpretability. In this regard, there is a real need for outline and comparative studies gathering benchmark and state-of-art PR techniques that allow for a deeper understanding thereof and a proper selection of a specific technique. This study conducted a topical overview of specialized papers covering lower-limb motor task identification through PR-based BCI/EEG signal analysis systems. To do so, we first established search terms and inclusion and exclusion criteria to find the most relevant papers on the subject. As a result, we identified the 22 most relevant papers. Next, we reviewed their experimental methodologies for recording EEG signals during the execution of lower limb tasks. In addition, we review the algorithms used in the preprocessing, feature extraction, and classification stages. Finally, we compared all the algorithms and determined which of them are the most suitable in terms of accuracy.
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Affiliation(s)
- Víctor Asanza
- Facultad de Ingeniería en Electricidad y Computación, Escuela Superior Politécnica del Litoral (ESPOL), Campus Gustavo Galindo km 30.5 Vía Perimetral, Guayaquil P.O. Box 09-01-5863, Ecuador;
| | - Enrique Peláez
- Facultad de Ingeniería en Electricidad y Computación, Escuela Superior Politécnica del Litoral (ESPOL), Campus Gustavo Galindo km 30.5 Vía Perimetral, Guayaquil P.O. Box 09-01-5863, Ecuador;
| | - Francis Loayza
- Neuroimaging and Bioengineering Laboratory (LNB), Facultad de Ingeniería en Mecánica y Ciencias de la Producción, Escuela Superior Politécnica del Litoral (ESPOL), Campus Gustavo Galindo km 30.5 Vía Perimetral, Guayaquil P.O. Box 09-01-5863, Ecuador;
| | | | - Diego H. Peluffo-Ordóñez
- Faculty of Engineering, Corporación Universitaria Autónoma de Nariño, Pasto 520001, Colombia;
- Modeling, Simulation and Data Analysis (MSDA) Research Program, Mohammed VI Polytechnic University, Ben Guerir 43150, Morocco
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3
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Flood MW, Grimm B. EntropyHub: An open-source toolkit for entropic time series analysis. PLoS One 2021; 16:e0259448. [PMID: 34735497 PMCID: PMC8568273 DOI: 10.1371/journal.pone.0259448] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/18/2021] [Indexed: 11/24/2022] Open
Abstract
An increasing number of studies across many research fields from biomedical engineering to finance are employing measures of entropy to quantify the regularity, variability or randomness of time series and image data. Entropy, as it relates to information theory and dynamical systems theory, can be estimated in many ways, with newly developed methods being continuously introduced in the scientific literature. Despite the growing interest in entropic time series and image analysis, there is a shortage of validated, open-source software tools that enable researchers to apply these methods. To date, packages for performing entropy analysis are often run using graphical user interfaces, lack the necessary supporting documentation, or do not include functions for more advanced entropy methods, such as cross-entropy, multiscale cross-entropy or bidimensional entropy. In light of this, this paper introduces EntropyHub, an open-source toolkit for performing entropic time series analysis in MATLAB, Python and Julia. EntropyHub (version 0.1) provides an extensive range of more than forty functions for estimating cross-, multiscale, multiscale cross-, and bidimensional entropy, each including a number of keyword arguments that allows the user to specify multiple parameters in the entropy calculation. Instructions for installation, descriptions of function syntax, and examples of use are fully detailed in the supporting documentation, available on the EntropyHub website- www.EntropyHub.xyz. Compatible with Windows, Mac and Linux operating systems, EntropyHub is hosted on GitHub, as well as the native package repository for MATLAB, Python and Julia, respectively. The goal of EntropyHub is to integrate the many established entropy methods into one complete resource, providing tools that make advanced entropic time series analysis straightforward and reproducible.
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Affiliation(s)
- Matthew W. Flood
- Human Motion, Orthopaedics, Sports Medicine and Digital Methods (HOSD), Luxembourg Institute of Health (LIH), Eich, Luxembourg
| | - Bernd Grimm
- Human Motion, Orthopaedics, Sports Medicine and Digital Methods (HOSD), Luxembourg Institute of Health (LIH), Eich, Luxembourg
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4
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Orkan Olcay B, Özgören M, Karaçalı B. On the characterization of cognitive tasks using activity-specific short-lived synchronization between electroencephalography channels. Neural Netw 2021; 143:452-474. [PMID: 34273721 DOI: 10.1016/j.neunet.2021.06.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/04/2021] [Accepted: 06/18/2021] [Indexed: 10/21/2022]
Abstract
Accurate characterization of brain activity during a cognitive task is challenging due to the dynamically changing and the complex nature of the brain. The majority of the proposed approaches assume stationarity in brain activity and disregard the systematic timing organization among brain regions during cognitive tasks. In this study, we propose a novel cognitive activity recognition method that captures the activity-specific timing parameters from training data that elicits maximal average short-lived pairwise synchronization between electroencephalography signals. We evaluated the characterization power of the activity-specific timing parameter triplets in a motor imagery activity recognition framework. The activity-specific timing parameter triplets consist of latency of the maximally synchronized signal segments from activity onset Δt, the time lag between maximally synchronized signal segments τ, and the duration of the maximally synchronized signal segments w. We used cosine-based similarity, wavelet bi-coherence, phase-locking value, phase coherence value, linearized mutual information, and cross-correntropy to calculate the channel synchronizations at the specific timing parameters. Recognition performances as well as statistical analyses on both BCI Competition-III dataset IVa and PhysioNet Motor Movement/Imagery dataset, indicate that the inter-channel short-lived synchronization calculated using activity-specific timing parameter triplets elicit significantly distinct synchronization profiles for different motor imagery tasks and can thus reliably be used for cognitive task recognition purposes.
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Affiliation(s)
- B Orkan Olcay
- Department of Electrical and Electronics Engineering, Izmir Institute of Technology, 35430, Urla, Izmir, Turkey.
| | - Murat Özgören
- Department of Biophysics, Faculty of Medicine, Near East University, 99138, Nicosia, Cyprus.
| | - Bilge Karaçalı
- Department of Electrical and Electronics Engineering, Izmir Institute of Technology, 35430, Urla, Izmir, Turkey.
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5
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Jiang X, Li X, Xing H, Huang X, Xu X, Li J. Brain Entropy Study on Obsessive-Compulsive Disorder Using Resting-State fMRI. Front Psychiatry 2021; 12:764328. [PMID: 34867549 PMCID: PMC8632866 DOI: 10.3389/fpsyt.2021.764328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/14/2021] [Indexed: 02/05/2023] Open
Abstract
Object: Brain entropy is a potential index in the diagnosis of mental diseases, but there are some differences in different brain entropy calculation, which may bring confusion and difficulties to the application of brain entropy. Based on the resting-state function magnetic resonance imaging (fMRI) we analyzed the differences of the three main brain entropy in the statistical significance, including approximate entropy (ApEn), sample entropy (SampEn) and fuzzy entropy (FuzzyEn), and studied the physiological reasons behind the difference through comparing their performance on obsessive-compulsive disorder (OCD) and the healthy control (HC). Method: We set patients with OCD as the experimental group and healthy subjects as the control group. The brain entropy of the OCD group and the HC are calculated, respectively, by voxel and AAL region. And then we analyzed the statistical differences of the three brain entropies between the patients and the control group. To compare the sensitivity and robustness of these three kinds of entropy, we also studied their performance by using certain signal mixed with noise. Result: Compare with the control group, almost the whole brain's ApEn and FuzzyEn of OCD are larger significantly. Besides, there are more brain regions with obvious differences when using ApEn comparing to using FuzzyEn. There was no statistical difference between the SampEn of OCD and HC. Conclusion: Brain entropy is a numerical index related to brain function and can be used as a supplementary biological index to evaluate brain state, which may be used as a reference for the diagnosis of mental illness. According to an analysis of certain signal mixed with noise, we conclude that FuzzyEn is more accurate considering sensitivity, stability and robustness of entropy.
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Affiliation(s)
- Xi Jiang
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China.,School of Physics, Sichuan University, Chengdu, China
| | - Xue Li
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China.,School of Physics, Sichuan University, Chengdu, China
| | - Haoyang Xing
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China.,School of Physics, Sichuan University, Chengdu, China
| | - Xiaoqi Huang
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xin Xu
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Jing Li
- Magnetic Resonance Research Center, West China Hospital, Sichuan University, Chengdu, China
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6
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Velasquez-Martinez L, Caicedo-Acosta J, Acosta-Medina C, Alvarez-Meza A, Castellanos-Dominguez G. Regression Networks for Neurophysiological Indicator Evaluation in Practicing Motor Imagery Tasks. Brain Sci 2020; 10:E707. [PMID: 33020435 PMCID: PMC7600302 DOI: 10.3390/brainsci10100707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 09/21/2020] [Accepted: 09/25/2020] [Indexed: 11/21/2022] Open
Abstract
Motor Imagery (MI) promotes motor learning in activities, like developing professional motor skills, sports gestures, and patient rehabilitation. However, up to 30% of users may not develop enough coordination skills after training sessions because of inter and intra-subject variability. Here, we develop a data-driven estimator, termed Deep Regression Network (DRN), which jointly extracts and performs the regression analysis in order to assess the efficiency of the individual brain networks in practicing MI tasks. The proposed double-stage estimator initially learns a pool of deep patterns, extracted from the input data, in order to feed a neural regression model, allowing for infering the distinctiveness between subject assemblies having similar variability. The results, which were obtained on real-world MI data, prove that the DRN estimator fosters pre-training neural desynchronization and initial training synchronization to predict the bi-class accuracy response, thus providing a better understanding of the Brain-Computer Interface inefficiency of subjects.
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Affiliation(s)
- Luisa Velasquez-Martinez
- Signal Processing and Recognition Group, Universidad Nacional de Colombia, Manizales 170004, Colombia; (J.C.-A.); (C.A.-M.); (A.A.-M.); (G.C.-D.)
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7
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Zhang X, D’Arcy R, Chen L, Xu M, Ming D, Menon C. The Feasibility of Longitudinal Upper Extremity Motor Function Assessment Using EEG. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5487. [PMID: 32992698 PMCID: PMC7582505 DOI: 10.3390/s20195487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/19/2020] [Accepted: 09/21/2020] [Indexed: 11/16/2022]
Abstract
Motor function assessment is crucial in quantifying motor recovery following stroke. In the rehabilitation field, motor function is usually assessed using questionnaire-based assessments, which are not completely objective and require prior training for the examiners. Some research groups have reported that electroencephalography (EEG) data have the potential to be a good indicator of motor function. However, those motor function scores based on EEG data were not evaluated in a longitudinal paradigm. The ability of the motor function scores from EEG data to track the motor function changes in long-term clinical applications is still unclear. In order to investigate the feasibility of using EEG to score motor function in a longitudinal paradigm, a convolutional neural network (CNN) EEG model and a residual neural network (ResNet) EEG model were previously generated to translate EEG data into motor function scores. To validate applications in monitoring rehabilitation following stroke, the pre-established models were evaluated using an initial small sample of individuals in an active 14-week rehabilitation program. Longitudinal performances of CNN and ResNet were evaluated through comparison with standard Fugl-Meyer Assessment (FMA) scores of upper extremity collected in the assessment sessions. The results showed good accuracy and robustness with both proposed networks (average difference: 1.22 points for CNN, 1.03 points for ResNet), providing preliminary evidence for the proposed method in objective evaluation of motor function of upper extremity in long-term clinical applications.
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Affiliation(s)
- Xin Zhang
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (X.Z.); (M.X.)
- Menrva Research Group, Schools of Mechatronic Systems Engineering and Engineering Science, Simon Fraser University, Metro Vancouver, BC V5A 1S6, Canada;
| | - Ryan D’Arcy
- Schools of Engineering Science and Computer Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Long Chen
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China;
| | - Minpeng Xu
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (X.Z.); (M.X.)
| | - Dong Ming
- Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China; (X.Z.); (M.X.)
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin 300072, China;
- Tianjin International Joint Research Center for Neural Engineering, Tianjin 300072, China
| | - Carlo Menon
- Menrva Research Group, Schools of Mechatronic Systems Engineering and Engineering Science, Simon Fraser University, Metro Vancouver, BC V5A 1S6, Canada;
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8
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Frolov NS, Pitsik EN, Maksimenko VA, Grubov VV, Kiselev AR, Wang Z, Hramov AE. Age-related slowing down in the motor initiation in elderly adults. PLoS One 2020; 15:e0233942. [PMID: 32937652 PMCID: PMC7494367 DOI: 10.1371/journal.pone.0233942] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/01/2020] [Indexed: 11/19/2022] Open
Abstract
Age-related changes in the human brain functioning crucially affect the motor system, causing increased reaction time, low ability to control and execute movements, difficulties in learning new motor skills. The lifestyle and lowered daily activity of elderly adults, along with the deficit of motor and cognitive brain functions, might lead to the developed ambidexterity, i.e., the loss of dominant limb advances. Despite the broad knowledge about the changes in cortical activity directly related to the motor execution, less is known about age-related differences in the motor initiation phase. We hypothesize that the latter strongly influences the behavioral characteristics, such as reaction time, the accuracy of motor performance, etc. Here, we compare the neuronal processes underlying the motor initiation phase preceding fine motor task execution between elderly and young subjects. Based on the results of the whole-scalp sensor-level electroencephalography (EEG) analysis, we demonstrate that the age-related slowing down in the motor initiation before the dominant hand movements is accompanied by the increased theta activation within sensorimotor area and reconfiguration of the theta-band functional connectivity in elderly adults.
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Affiliation(s)
- Nikita S. Frolov
- Neuroscience and Cognitive Technology Laboratory, Innopolis University, Innopolis, The Republic of Tatarstan, Russia
- * E-mail:
| | - Elena N. Pitsik
- Neuroscience and Cognitive Technology Laboratory, Innopolis University, Innopolis, The Republic of Tatarstan, Russia
| | - Vladimir A. Maksimenko
- Neuroscience and Cognitive Technology Laboratory, Innopolis University, Innopolis, The Republic of Tatarstan, Russia
| | - Vadim V. Grubov
- Neuroscience and Cognitive Technology Laboratory, Innopolis University, Innopolis, The Republic of Tatarstan, Russia
- Saratov State Medical University, Saratov, Russia
| | | | - Zhen Wang
- Northwestern Polytechnical University, Xi’an, Shaanxi, China
| | - Alexander E. Hramov
- Neuroscience and Cognitive Technology Laboratory, Innopolis University, Innopolis, The Republic of Tatarstan, Russia
- Saratov State Medical University, Saratov, Russia
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9
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Velasquez-Martinez L, Caicedo-Acosta J, Castellanos-Dominguez G. Entropy-Based Estimation of Event-Related De/Synchronization in Motor Imagery Using Vector-Quantized Patterns. ENTROPY 2020; 22:e22060703. [PMID: 33286475 PMCID: PMC7517241 DOI: 10.3390/e22060703] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/23/2020] [Accepted: 05/26/2020] [Indexed: 02/07/2023]
Abstract
Assessment of brain dynamics elicited by motor imagery (MI) tasks contributes to clinical and learning applications. In this regard, Event-Related Desynchronization/Synchronization (ERD/S) is computed from Electroencephalographic signals, which show considerable variations in complexity. We present an Entropy-based method, termed VQEnt, for estimation of ERD/S using quantized stochastic patterns as a symbolic space, aiming to improve their discriminability and physiological interpretability. The proposed method builds the probabilistic priors by assessing the Gaussian similarity between the input measured data and their reduced vector-quantized representation. The validating results of a bi-class imagine task database (left and right hand) prove that VQEnt holds symbols that encode several neighboring samples, providing similar or even better accuracy than the other baseline sample-based algorithms of Entropy estimation. Besides, the performed ERD/S time-series are close enough to the trajectories extracted by the variational percentage of EEG signal power and fulfill the physiological MI paradigm. In BCI literate individuals, the VQEnt estimator presents the most accurate outcomes at a lower amount of electrodes placed in the sensorimotor cortex so that reduced channel set directly involved with the MI paradigm is enough to discriminate between tasks, providing an accuracy similar to the performed by the whole electrode set.
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10
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Shafer RL, Solomon EM, Newell KM, Lewis MH, Bodfish JW. Visual feedback during motor performance is associated with increased complexity and adaptability of motor and neural output. Behav Brain Res 2019; 376:112214. [PMID: 31494179 DOI: 10.1016/j.bbr.2019.112214] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/30/2019] [Accepted: 09/04/2019] [Indexed: 11/19/2022]
Abstract
Complex motor behavior is believed to be dependent on sensorimotor integration - the neural process of using sensory input to plan, guide, and correct movements. Previous studies have shown that the complexity of motor output is low when sensory feedback is withheld during precision motor tasks. However, much of this research has focused on motor behavior rather than neural processing, and therefore, has not specifically assessed the role of sensorimotor neural functioning in the execution of complex motor behavior. The present study uses a stimulus-tracking task with simultaneous electroencephalography (EEG) recording to assess the effect of visual feedback on motor performance, motor complexity, and sensorimotor neural processing in healthy adults. The complexity of the EEG signal was analyzed to capture the information content in frequency bands (alpha and beta) and scalp regions (central, parietal, and occipital) that are associated with sensorimotor processing. Consistent with previous literature, motor performance and its complexity were higher when visual feedback was provided relative to when it was withheld. The complexity of the neural signal was also higher when visual feedback was provided. This was most robust at frequency bands (alpha and beta) and scalp regions (parietal and occipital) associated with sensorimotor processing. The findings show that visual feedback increases the information available to the brain when generating complex, adaptive motor output.
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Affiliation(s)
- Robin L Shafer
- Vanderbilt Brain Institute, Vanderbilt University, 6133 Medical Research Building III, 465 21st Avenue South, Nashville, TN, 37232, USA.
| | - Eli M Solomon
- Neuroscience and Behavior Program, Wesleyan University Rm 257 Hall-Atwater, Wesleyan University, Middletown, CT, 06459, USA.
| | - Karl M Newell
- Department of Kinesiology, University of Georgia, G3 Aderhold Hall, 110 Carlton Street, Athens, GA, 30602, USA.
| | - Mark H Lewis
- Department of Psychiatry, University of Florida College of Medicine, PO Box 100256, L4-100 McKnight Brain Institute, 1149 Newell Drive, Gainesville, FL, 32611, USA.
| | - James W Bodfish
- Vanderbilt Brain Institute, Vanderbilt University, 6133 Medical Research Building III, 465 21st Avenue South, Nashville, TN, 37232, USA; Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, 8310 Medical Center East, 1215 21st Avenue South, Nashville, TN, 37232, USA.
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11
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Pu J, Xu H, Wang Y, Cui H, Hu Y. Combined nonlinear metrics to evaluate spontaneous EEG recordings from chronic spinal cord injury in a rat model: a pilot study. Cogn Neurodyn 2016; 10:367-73. [PMID: 27668016 PMCID: PMC5018015 DOI: 10.1007/s11571-016-9394-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 06/09/2016] [Accepted: 06/23/2016] [Indexed: 11/26/2022] Open
Abstract
Spinal cord injury (SCI) is a high-cost disability and may cause permanent loss of movement and sensation below the injury location. The chance of cure in human after SCI is extremely limited. Instead, neural regeneration could have been seen in animals after SCI, and such regeneration could be retarded by blocking neural plasticity pathways, showing the importance of neural plasticity in functional recovery. As an indicator of nonlinear dynamics in the brain, sample entropy was used here in combination with detrended fluctuation analysis (DFA) and Kolmogorov complexity to quantify functional plasticity changes in spontaneous EEG recordings of rats before and after SCI. The results showed that the sample entropy values were decreased at the first day following injury then gradually increased during recovery. DFA and Kolmogorov complexity results were in consistent with sample entropy, showing the complexity of the EEG time series was lost after injury and partially regained in 1 week. The tendency to regain complexity is in line with the observation of behavioral rehabilitation. A critical time point was found during the recovery process after SCI. Our preliminary results suggested that the combined use of these nonlinear dynamical metrics could provide a quantitative and predictive way to assess the change of neural plasticity in a spinal cord injury rat model.
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Affiliation(s)
- Jiangbo Pu
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
| | - Hanhui Xu
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
| | - Yazhou Wang
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
- Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Hongyan Cui
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
| | - Yong Hu
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People’s Republic of China
- Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, People’s Republic of China
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12
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Gao L, Cheng W, Zhang J, Wang J. EEG classification for motor imagery and resting state in BCI applications using multi-class Adaboost extreme learning machine. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:085110. [PMID: 27587163 DOI: 10.1063/1.4959983] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Brain-computer interface (BCI) systems provide an alternative communication and control approach for people with limited motor function. Therefore, the feature extraction and classification approach should differentiate the relative unusual state of motion intention from a common resting state. In this paper, we sought a novel approach for multi-class classification in BCI applications. We collected electroencephalographic (EEG) signals registered by electrodes placed over the scalp during left hand motor imagery, right hand motor imagery, and resting state for ten healthy human subjects. We proposed using the Kolmogorov complexity (Kc) for feature extraction and a multi-class Adaboost classifier with extreme learning machine as base classifier for classification, in order to classify the three-class EEG samples. An average classification accuracy of 79.5% was obtained for ten subjects, which greatly outperformed commonly used approaches. Thus, it is concluded that the proposed method could improve the performance for classification of motor imagery tasks for multi-class samples. It could be applied in further studies to generate the control commands to initiate the movement of a robotic exoskeleton or orthosis, which finally facilitates the rehabilitation of disabled people.
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Affiliation(s)
- Lin Gao
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Biomedical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, People's Republic of China
| | - Wei Cheng
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, People's Republic of China
| | - Jinhua Zhang
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, People's Republic of China
| | - Jue Wang
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Biomedical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, People's Republic of China
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