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He X, Sun W, Song R, Xu W. Wavelet Coherence Analysis of Post-Stroke Intermuscular Coupling Modulated by Myoelectric-Controlled Interfaces. Bioengineering (Basel) 2024; 11:802. [PMID: 39199760 PMCID: PMC11351678 DOI: 10.3390/bioengineering11080802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Revised: 08/01/2024] [Accepted: 08/06/2024] [Indexed: 09/01/2024] Open
Abstract
Intermuscular coupling reflects the corticospinal interaction associated with the control of muscles. Nevertheless, the deterioration of intermuscular coupling caused by stroke has not received much attention. The purpose of this study was to investigate the effect of myoelectric-controlled interface (MCI) dimensionality on the intermuscular coupling after stroke. In total, ten age-matched controls and eight stroke patients were recruited and executed elbow tracking tasks within 1D or 2D MCI. Movement performance was quantified using the root mean square error (RMSE). Wavelet coherence was used to analyze the intermuscular coupling in alpha band (8-12 Hz) and beta band (15-35 Hz). The results found that smaller RMSE of antagonist muscles was observed in both groups within 2D MCI compared to 1D MCI. The alpha-band wavelet coherence was significantly lower in the patients compared to the controls during elbow extension. Furthermore, a decreased alpha-band and beta-band wavelet coherence was observed in the controls and stroke patients, as the dimensionality of MCI increased. These results may suggest that stroke-related neural impairments deteriorate the motor performance and intermuscular coordination pattern, and, further, that MCI holds promise as a novel effective tool for rehabilitation through the direct modulation of muscle activation pattern.
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Affiliation(s)
- Xinyi He
- School of Biomedical Engineering, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China; (X.H.); (W.S.)
| | - Wenbo Sun
- School of Biomedical Engineering, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China; (X.H.); (W.S.)
| | - Rong Song
- School of Biomedical Engineering, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, China; (X.H.); (W.S.)
- Shenzhen Research Institute of Sun Yat-sen University, Shenzhen 518107, China
| | - Weiling Xu
- School of Information Science and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou 510408, China
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Heintz Walters B, Huddleston WE, O'Connor K, Wang J, Hoeger Bement M, Keenan KG. Visual feedback and declines in attention are associated with altered visual strategy during a force-steadiness task in older adults. J Neurophysiol 2023; 130:1309-1320. [PMID: 37877175 DOI: 10.1152/jn.00486.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 09/07/2023] [Accepted: 10/16/2023] [Indexed: 10/26/2023] Open
Abstract
Greater heterogeneity exists in older adults relative to young adults when performing highly skilled manual tasks. The purpose of this study was to assess the influence of visual feedback and attentional demand on visual strategy during a submaximal force-steadiness task in young and older adults. Eye movements of 21 young (age 20-38 yr; 11 females, 10 males) and 21 older (age 65-90 yr; 11 females, 10 males) adults were recorded during a pinch force-steadiness task while viewing feedback with higher and lower gain and while performing a visuospatial task. For the visuospatial task, participants imagined a star moving around four boxes and reported the final location after a series of directions. Performance on standardized tests of attention was measured. All participants gazed near the target line and made left-to-right saccadic eye movements during the force-steadiness tasks without the visuospatial task. Older adults made fewer saccades than young adults (21.0 ± 2.9 and 23.6 ± 4.4 saccades, respectively) and with higher versus lower gain (20.9 ± 4.0 and 23.7 ± 3.5 saccades, respectively). Most participants used the same visual strategy when performing the visuospatial task though seven older adults used an altered strategy; gaze did not stay near the target line nor travel exclusively left to right. Performance on standardized measures of attention was impaired in this subset compared with older adults who did not use the altered visual strategy. Results indicate that visual feedback influences visual strategy and reveals unique eye movements in some older adults when allocating attention across tasks.NEW & NOTEWORTHY This study contributes novel findings of age-related changes in visual strategy and associations with attentional deficits during hand motor tasks. Older adults used fewer saccades than young adults and with higher versus lower gain visual feedback during a force-steadiness task. A subset of older adults used an altered visual strategy when allocating attention across multiple tasks. Given that this subset demonstrated attentional deficits, the altered visual strategy could serve to indicate motor and/or cognitive impairments.
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Affiliation(s)
| | - Wendy E Huddleston
- Department of Rehabilitation Sciences & Technology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States
| | - Kristian O'Connor
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States
| | - Jinsung Wang
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States
| | - Marie Hoeger Bement
- Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, United States
| | - Kevin G Keenan
- Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States
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Lin YT, Chen YC, Chang GC, Hwang IS. Failure to improve task performance after visuomotor training with error reduction feedback for young adults. Front Physiol 2023; 14:1066325. [PMID: 36969593 PMCID: PMC10030953 DOI: 10.3389/fphys.2023.1066325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/22/2023] [Indexed: 03/29/2023] Open
Abstract
Visual feedback that reinforces accurate movements may motivate skill acquisition by promoting self-confidence. This study investigated neuromuscular adaptations to visuomotor training with visual feedback with virtual error reduction. Twenty-eight young adults (24.6 ± 1.6 years) were assigned to error reduction (ER) (n = 14) and control (n = 14) groups to train on a bi-rhythmic force task. The ER group received visual feedback and the displayed errors were 50% of the real errors in size. The control group was trained with visual feedback with no reduction in errors. Training-related differences in task accuracy, force behaviors, and motor unit discharge were contrasted between the two groups. The tracking error of the control group progressively declined, whereas the tracking error of the ER group was not evidently reduced in the practice sessions. In the post-test, only the control group exhibited significant task improvements with smaller error size (p = .015) and force enhancement at the target frequencies (p = .001). The motor unit discharge of the control group was training-modulated, as indicated by a reduction of the mean inter-spike interval (p = .018) and smaller low-frequency discharge fluctuations (p = .017) with enhanced firing at the target frequencies of the force task (p = .002). In contrast, the ER group showed no training-related modulation of motor unit behaviors. In conclusion, for young adults, ER feedback does not induce neuromuscular adaptations to the trained visuomotor task, which is conceptually attributable to intrinsic error dead-zones.
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Affiliation(s)
- Yen-Ting Lin
- Department of Ball Sport, National Taiwan University of Sport, Taichung City, Taiwan
| | - Yi-Ching Chen
- Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung City, Taiwan
- Physical Therapy Room, Chung Shan Medical University Hospital, Taichung City, Taiwan
| | - Gwo-Ching Chang
- Department of Information Engineering, I-Shou University, Kaohsiung City, Taiwan
| | - Ing-Shiou Hwang
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan City, Taiwan
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan City, Taiwan
- *Correspondence: Ing-Shiou Hwang,
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Lee H, Park YM, Kang N. Unilateral hand force control impairments in older women. EXCLI JOURNAL 2022; 21:1231-1244. [PMID: 36381646 PMCID: PMC9650698 DOI: 10.17179/excli2022-5362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 09/20/2022] [Indexed: 11/25/2022]
Abstract
Older women may experience deficits in sensorimotor control at their upper limb because of aging progress compromising the motor system. This study aimed to investigate whether younger and older women differ in sensorimotor capabilities assessed by unilateral force control performances at a lower targeted force level. Twenty-one older and 21 younger women performed isometric unilateral force control tasks at 10 % of maximum voluntary contraction for each hand, respectively. Purdue Pegboard Test (PPT) was used to measure unilateral hand dexterity. Five force control variables (i.e., maximal and submaximal force, force error, variability, and regularity) and PPT scores were analyzed in two-way mixed ANOVAs (Group × Hand Condition), respectively. The absolute force power was analyzed in three-way mixed ANOVA (Group × Hand Condition × Frequency Band). The findings revealed that older women produced less maximal and submaximal unilateral forces than in younger women. Greater variability, regularity, and force frequency oscillations below 4 Hz were observed in older women as compared with those in younger women. Force error in the dominant hand was greater in older women than those in younger women. Finally, older women showed lower PPT scores than younger women. These findings suggested that older women may have deficits in unilateral force control capabilities as well as motor dexterity.
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Affiliation(s)
- Hanall Lee
- Department of Human Movement Science, Incheon National University, Incheon, South Korea,Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, Incheon, South Korea
| | - Young-Min Park
- Division of Health and Kinesiology, Incheon National University, Incheon, South Korea,Sport Science Institute & Health Promotion Center, Incheon National University, Incheon, South Korea
| | - Nyeonju Kang
- Department of Human Movement Science, Incheon National University, Incheon, South Korea,Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, Incheon, South Korea,Sport Science Institute & Health Promotion Center, Incheon National University, Incheon, South Korea,Division of Sport Science & Sport Science Institute, Incheon National University, Incheon, South Korea,*To whom correspondence should be addressed: Nyeonju Kang, Neuromechanical Rehabilitation Research Laboratory, Division of Sport Science, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, South Korea; Phone: +82 32 835 8573, Fax: +82 32 835 0788, E-mail:
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Cortical reorganization to improve dynamic balance control with error amplification feedback. J Neuroeng Rehabil 2022; 19:3. [PMID: 35034661 PMCID: PMC8762892 DOI: 10.1186/s12984-022-00980-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 12/29/2021] [Indexed: 11/21/2022] Open
Abstract
Background Error amplification (EA), virtually magnify task errors in visual feedback, is a potential neurocognitive approach to facilitate motor performance. With regional activities and inter-regional connectivity of electroencephalography (EEG), this study investigated underlying cortical mechanisms associated with improvement of postural balance using EA. Methods Eighteen healthy young participants maintained postural stability on a stabilometer, guided by two visual feedbacks (error amplification (EA) vs. real error (RE)), while stabilometer plate movement and scalp EEG were recorded. Plate dynamics, including root mean square (RMS), sample entropy (SampEn), and mean frequency (MF) were used to characterize behavioral strategies. Regional cortical activity and inter-regional connectivity of EEG sub-bands were characterized to infer neural control with relative power and phase-lag index (PLI), respectively. Results In contrast to RE, EA magnified the errors in the visual feedback to twice its size during stabilometer stance. The results showed that EA led to smaller RMS of postural fluctuations with greater SampEn and MF than RE did. Compared with RE, EA altered cortical organizations with greater regional powers in the mid-frontal cluster (theta, 4–7 Hz), occipital cluster (alpha, 8–12 Hz), and left temporal cluster (beta, 13–35 Hz). In terms of the phase-lag index of EEG between electrode pairs, EA significantly reduced long-range prefrontal-parietal and prefrontal-occipital connectivity of the alpha/beta bands, and the right tempo-parietal connectivity of the theta/alpha bands. Alternatively, EA augmented the fronto-centro-parietal connectivity of the theta/alpha bands, along with the right temporo-frontal and temporo-parietal connectivity of the beta band. Conclusion EA alters postural strategies to improve stance stability on a stabilometer with visual feedback, attributable to enhanced error processing and attentional release for target localization. This study provides supporting neural correlates for the use of virtual reality with EA during balance training.
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Hwang IS, Hu CL, Huang WM, Tsai YY, Chen YC. Potential Motor Benefits of Visual Feedback of Error Reduction for Older Adults. J Aging Phys Act 2020; 28:934-942. [PMID: 32702665 DOI: 10.1123/japa.2019-0405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 04/13/2020] [Accepted: 04/20/2020] [Indexed: 11/18/2022]
Abstract
This study investigated how visual feedback of virtual error reduction (ER) modified the visuomotor performance of older adults with limited attentional capacity. Error structures of young and older adults during birhythmic force tracking were contrasted when the visualized error size was exact or half of the actual size. As compared with full-size error feedback, ER feedback improved the force tracking symmetry of older adults, but undermined that of young adults. Extended Poincaré analysis revealed that young adults presented greater short-term error variability (mean value of κ-lagged SD1 of the error signal) with ER feedback, which led to a smaller mean value of κ-lagged SD1 of the error signal for older adults. The ER-related task improvement of the older adults was negatively correlated with the size of the tracking errors with real error feedback and positively correlated with ER-related increases in force spectral symmetry and decreases in the mean value of κ-lagged SD1 of the error signal. ER feedback could advance visuomotor tasks for older adults who perform worse with full-size visual feedback by the enhancement of self-efficacy and stabilization of negative internal feedback.
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Watanabe T, Nojima I, Mima T, Sugiura H, Kirimoto H. Magnification of visual feedback modulates corticomuscular and intermuscular coherences differently in young and elderly adults. Neuroimage 2020; 220:117089. [DOI: 10.1016/j.neuroimage.2020.117089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/05/2020] [Accepted: 06/21/2020] [Indexed: 10/24/2022] Open
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Hwang IS, Lin YT, Huang CC, Chen YC. Fatigue-related modulation of low-frequency common drive to motor units. Eur J Appl Physiol 2020; 120:1305-1317. [PMID: 32297005 DOI: 10.1007/s00421-020-04363-z] [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: 09/23/2019] [Accepted: 04/01/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE This study investigated fatigue-related modulation of common neural inputs to motor units (MUs) under 5 Hz, which determines force precision control. METHODS Twenty-seven adults performed a sequence of fatiguing contractions. The participants were assessed with a static isometric index abduction at 20% maximal voluntary contraction in the pre-test and post-test. Discharge characteristics of MUs of the first dorsal interosseous muscle were analyzed with decomposed EMG signals. RESULTS Along with increases in the mean (58.40 ± 11.76 ms → 62.55 ± 10.83 ms, P = 0.029) and coefficient of variation (0.204 ± .014 → 0.215 ± 0.017, P = 0.002) in inter-spike intervals, the fatiguing contraction caused reductions in the mean frequency (16.84 ± 3.31 Hz → 15.59 ± 3.21 Hz, P = 0.027) and spectral dispersions (67.54 ± 4.49 → 62.64 ± 6.76 Hz, P = 0.007) of common neural drive, as estimated with smoothed cumulative motor unit spike trains (SCMUSTs). Stabilogram diffusion analysis of SCMUSTs revealed significant fatigue-related reductions in the long-term effective diffusion coefficient (1.91 ± 0.77 Hz2/s → 1.61 ± 0.61 Hz2/s, P = 0.020) and long-term scaling exponent (0.480 ± 0.013 Hz2/s → 0.471 ± 0.017 Hz2/s, P = 0.014). After fatiguing contraction, mutual information of force fluctuations and SCMUSTs was augmented roughly by 12.95% (P = 0.041). CONCLUSIONS Muscular fatigue could compress and shift the low-frequency common drive to MUs toward lower spectral bands, thereby enhancing transmission of twitch forces through the muscle-tendon complex with a low-pass filter property. The fatigue-induced changes involve increased closed-loop control of the common modulation of MU discharge rates.
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Affiliation(s)
- Ing-Shiou Hwang
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan.,Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Yen-Ting Lin
- Physical Education Office, Asian University, Taichung, 41354, Taiwan
| | - Chien-Chun Huang
- Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ching Chen
- Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung, 40201, Taiwan. .,Physical Therapy Room, Chung Shan Medical University Hospital, Taichung, 40201, Taiwan.
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Contrasting Age Effects on Complexity of Tracking Force and Force Fluctuations During Monorhythmic Contraction. J Aging Phys Act 2020; 28:114-121. [PMID: 31629359 DOI: 10.1123/japa.2019-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 05/20/2019] [Accepted: 05/30/2019] [Indexed: 11/18/2022]
Abstract
This study contrasted the stochastic force component between young and older adults, who performed pursuit tracking/compensatory tracking by exerting in-phase/antiphase forces to match a sinusoidal target. Tracking force was decomposed into the force component containing the target frequency and the nontarget force fluctuations (stochastic component). Older adults with inferior task performance had higher complexity (entropy across time; p = .005) in total force. For older adults, task errors were negatively correlated with force fluctuation complexity (pursuit tracking: r = -.527 to -.551; compensatory tracking: r = -.626 to -.750). Notwithstanding an age-related increase in total force complexity (p = .004), older adults exhibited lower complexity of the stochastic force component than young adults did (low frequency: p = .017; high frequency: p = .035). Those older adults with a higher complexity of stochastic force had better task performance due to the underlying use of a richer gradation strategy to compensate for impaired oscillatory control.
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Kang N, Roberts LM, Aziz C, Cauraugh JH. Age-related deficits in bilateral motor synergies and force coordination. BMC Geriatr 2019; 19:287. [PMID: 31651243 PMCID: PMC6814115 DOI: 10.1186/s12877-019-1285-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 09/20/2019] [Indexed: 11/21/2022] Open
Abstract
Background Ageing may cause impairments in executing bilateral movement control. This study investigated age-related changes in interlimb force coordination across multiple trials by quantifying bilateral motor synergies based on the uncontrolled manifold hypothesis. Participants completed the trials with and without visual feedback. Methods Twenty healthy individuals (10 older adults and 10 young adults) performed 12 isometric force control trials for the two vision conditions at 5% of maximal voluntary contraction. All dependent variables were analyzed in two-way mixed model (Group × Vision Condition; 2 × 2) ANOVAs with repeated measures on the last factor. Results The analyses revealed that older adults had greater mean force produced by two hands in both vision conditions (i.e., yes and no visual feedback). Across both vision conditions, the older adult group showed greater asymmetrical force variability (i.e., standard deviation of non-dominant hand > standard deviation of dominant hand) and revealed more positive correlation coefficients between forces produced by two hands as compared with the young adult group. Finally, an index of bilateral motor synergies was significantly greater in young adults than older adults when visual feedback was available. Conclusion The current findings indicate that deficits in interlimb force coordination across multiple trials appeared in older adults.
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Affiliation(s)
- Nyeonju Kang
- Division of Sport Science and Sport Science Institute, Incheon, South Korea.,Neuromechanical Rehabilitation Research Laboratory, Incheon National University, Incheon, South Korea.,Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA
| | - Lisa M Roberts
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA.,Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Clara Aziz
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA
| | - James H Cauraugh
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, 32611-8206, USA.
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Hwang IS, Hu CL, Yang ZR, Lin YT, Chen YC. Improving Precision Force Control With Low-Frequency Error Amplification Feedback: Behavioral and Neurophysiological Mechanisms. Front Physiol 2019; 10:131. [PMID: 30842742 PMCID: PMC6391708 DOI: 10.3389/fphys.2019.00131] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 02/01/2019] [Indexed: 11/13/2022] Open
Abstract
Although error amplification (EA) feedback has been shown to improve performance on visuomotor tasks, the challenge of EA is that it concurrently magnifies task-irrelevant information that may impair visuomotor control. The purpose of this study was to improve the force control in a static task by preclusion of high-oscillatory components in EA feedback that cannot be timely used for error correction by the visuomotor system. Along with motor unit behaviors and corticomuscular coherence, force fluctuations (Fc) were modeled with non-linear SDA to contrast the reliance of the feedback process and underlying neurophysiological mechanisms by using real feedback, EA, and low-frequency error amplification (LF-EA). During the static force task in the experiment, the EA feedback virtually potentiated the size of visual error, whereas the LF-EA did not channel high-frequency errors above 0.8 Hz into the amplification process. The results showed that task accuracy was greater with the LF-EA than with the real and EA feedback modes, and that LF-EA led to smaller and more complex Fc. LF-EA generally led to smaller SDA variables of Fc (critical time points, critical point of Fc, the short-term effective diffusion coefficient, and short-term exponent scaling) than did real feedback and EA. The use of LF-EA feedback increased the irregularity of the ISIs of MUs but decreased the RMS of the mean discharge rate, estimated with pooled MU spike trains. Beta-range EEG–EMG coherence spectra (13–35 Hz) in the LF-EA condition were the greatest among the three feedback conditions. In summary, amplification of low-frequency errors improves force control by shifting the relative significances of the feedforward and feedback processes. The functional benefit arises from the increase in the common descending drive to promote a stable state of MU discharges.
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Affiliation(s)
- Ing-Shiou Hwang
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Ling Hu
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Zong-Ru Yang
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yen-Ting Lin
- Physical Education Office, Asian University, Taichung, Taiwan
| | - Yi-Ching Chen
- Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung, Taiwan.,Physical Therapy Room, Chung Shan Medical University Hospital, Taichung, Taiwan
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Chen YC, Lin LL, Hwang IS. Novel Behavioral and Neural Evidences for Age-Related changes in Force complexity. J Gerontol A Biol Sci Med Sci 2018; 73:997-1002. [PMID: 29471388 DOI: 10.1093/gerona/gly025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 02/16/2018] [Indexed: 12/22/2022] Open
Abstract
This study investigated age-related changes in behavioral and neural complexity for a polyrhythmic movement, which appeared to be an exception to the loss of complexity hypothesis. Young (n = 15; age = 24.2 years) and older (15; 68.1 years) adults performed low-level force-tracking with isometric index abduction to couple a compound sinusoidal target. Multiscale entropy (MSE) of tracking force and inter-spike interval (ISI) of motor unit (MU) in the first dorsal interosseus muscle were assessed. The MSE area of tracking force at shorter time scales of older adults was greater (more complex) than that of young adults, whereas an opposite trend (less complex for the elders) was noted at longer time scales. The MSE area of force fluctuations (the stochastic component of the tracking force) were generally smaller (less complex) for older adults. Along with greater mean and coefficient of ISI, the MSE area of the cumulative discharge rate of elders tended to be lower (less complex) than that of young adults. In conclusion, age-related complexity changes in polyrhythmic force-tracking depended on the time scale. The adaptive behavioral consequences could be multifactorial origins of the age-related impairment in rate coding, increased discharge noises, and lower discharge complexity of pooled MUs.
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Affiliation(s)
- Yi-Ching Chen
- Department of Physical Therapy, College of Medical Science and Technology, Chung Shan Medical University, Taichung City, Taiwan.,Physical Therapy Room, Chung Shan Medical University Hospital, Taichung City, Taiwan
| | - Linda L Lin
- Institute of Physical Education, Health and Leisure Studies, National Cheng Kung University, Tainan City, Taiwan
| | - Ing-Shiou Hwang
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan City, Taiwan.,Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan City, Taiwan
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