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van Dieën JH, Kistemaker DA. Increased velocity feedback gains in the presence of sensory noise can explain paradoxical changes in trunk motor control related to back pain. J Biomech 2024; 162:111876. [PMID: 37989619 DOI: 10.1016/j.jbiomech.2023.111876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/23/2023]
Abstract
Literature reports paradoxical findings regarding effects of low-back pain (LBP) on trunk motor control. Compared to healthy individuals, patients with LBP, especially those with high pain-related anxiety, showed stronger trunk extensor reflexes and more resistance against perturbations. On the other hand, LBP patients and especially those with high pain-related anxiety showed decreased precision in unperturbed trunk movement and posture. These paradoxical effects might be explained by arousal potentially increasing average and variance of muscle spindle firing rates. Increased average firing rates could increase resistance against perturbations, but increased variance could decrease precision. We performed a simulation study to test this hypothesis. We modeled the trunk as a 2D inverted pendulum, stabilized by two antagonistic Hill-type muscles, based on their open-loop muscle activation dependent intrinsic stiffness and damping and through 25 ms-delayed, noisy contractile element length and velocity feedback. Reference feedback gains and sensory noise levels were tuned based on previously reported experimental data. We assessed the effect of increasing feedback gains on precision of trunk orientation at different perturbation magnitudes and assessed sensitivity of the effects to open-loop muscle stimulation and noise levels. At low perturbation magnitudes, increasing reflex gains consistently caused an increase in the variance of trunk orientation. At larger perturbation magnitudes, increasing reflex gains consistently caused a decrease in the variance of trunk orientation. Our results support the notion that LBP and related anxiety may increase reflex gains, resulting in an increase in the average and variance of spindle afference, which in turn increase resistance against perturbations and decrease movement precision.
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Affiliation(s)
- Jaap H van Dieën
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands.
| | - Dinant A Kistemaker
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, the Netherlands
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Bzdúšková D, Marko M, Hirjaková Z, Riečanský I, Kimijanová J. Fear of heights shapes postural responses to vibration-induced balance perturbation at virtual height. Front Hum Neurosci 2023; 17:1229484. [PMID: 37771346 PMCID: PMC10523023 DOI: 10.3389/fnhum.2023.1229484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/21/2023] [Indexed: 09/30/2023] Open
Abstract
Introduction Standing upright at height is a challenging situation involving intense threat of balance loss and fall. The ability to maintain balance in such conditions requires properly resolving sensory conflicts and is influenced by fear. To get more insight on the role of fear in balance control at height, we explored the dynamics of postural behavior in the situation of enhanced threat of potential balance loss. Methods In 40 young individuals with varying fear of heights, we combined simulated exposure to height in a virtual reality environment with bilateral vibration of tibialis anterior muscles which evokes posture destabilization (the so-called vibration-induced falling). Results Under such condition of enhanced postural threat, individuals with intense fear of heights showed stronger stiffening of posture compared with individuals with low fear of heights who react more flexibly and adaptively to posture destabilization. This group difference was evident already at ground level but further increased during virtual height exposure. Discussion Our data show that fear of height significantly affects posture adaptation to balance-destabilizing events. Our findings demonstrate that the assessment of postural behavior during threatening situations in the virtual reality environment provides valuable insights into the mechanisms of balance control and may be used to develop novel strategies aimed at prevention of falls.
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Affiliation(s)
- Diana Bzdúšková
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Martin Marko
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia
- Department of Applied Informatics, Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Bratislava, Slovakia
| | - Zuzana Hirjaková
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Igor Riečanský
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia
- Department of Psychiatry, Faculty of Medicine, Slovak Medical University in Bratislava, Bratislava, Slovakia
| | - Jana Kimijanová
- Department of Behavioural Neuroscience, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovakia
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Cleworth TW, Peters RM, Chua R, Inglis JT, Carpenter MG. Effects of postural threat on perceptions of lower leg somatosensory stimuli during standing. Front Neurosci 2023; 17:1191976. [PMID: 37621714 PMCID: PMC10445653 DOI: 10.3389/fnins.2023.1191976] [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: 03/27/2023] [Accepted: 07/04/2023] [Indexed: 08/26/2023] Open
Abstract
Height-induced postural threat affects emotional state and standing balance behaviour during static, voluntary, and dynamic tasks. Facing a threat to balance also affects sensory and cortical processes during balance tasks. As sensory and cognitive functions are crucial in forming perceptions of movement, balance-related changes during threatening conditions might be associated with changes in conscious perceptions. Therefore, the purpose of this study was to examine the changes and potential mechanisms underlying conscious perceptions of balance-relevant information during height-induced postural threat. A combination of three experimental procedures utilized height-induced postural threat to manipulate emotional state, balance behavior, and/or conscious perceptions of balance-related stimuli. Experiment 1 assessed conscious perception of foot position during stance. During continuous antero-posterior pseudorandom support surface rotations, perceived foot movement was larger while actual foot movement did not change in the High (3.2 m, at the edge) compared to Low (1.1 m, away from edge) height conditions. Experiment 2 and 3 assessed somatosensory perceptual thresholds during upright stance. Perceptual thresholds for ankle rotations were elevated while foot sole vibrations thresholds remained unchanged in the High compared to Low condition. This study furthers our understanding of the relationship between emotional state, sensory perception, and balance performance. While threat can influence the perceived amplitude of above threshold ankle rotations, there is a reduction in the sensitivity of an ankle rotation without any change to foot sole sensitivity. These results highlight the effect of postural threat on neurophysiological and cognitive components of balance control and provide insight into balance assessment and intervention.
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Affiliation(s)
- Taylor W. Cleworth
- School of Kinesiology and Health Science, York University, Toronto, ON, Canada
- Centre for Vision Research, York University, Toronto, ON, Canada
| | - Ryan M. Peters
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Romeo Chua
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - J. Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
- International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
| | - Mark G. Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
- International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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Cheng X, Bao B, Cui W, Liu S, Zhong J, Cai L, Yang H. Classification and Analysis of Human Body Movement Characteristics Associated with Acrophobia Induced by Virtual Reality Scenes of Heights. SENSORS (BASEL, SWITZERLAND) 2023; 23:5482. [PMID: 37420652 DOI: 10.3390/s23125482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/26/2023] [Accepted: 06/08/2023] [Indexed: 07/09/2023]
Abstract
Acrophobia (fear of heights), a prevalent psychological disorder, elicits profound fear and evokes a range of adverse physiological responses in individuals when exposed to heights, which will lead to a very dangerous state for people in actual heights. In this paper, we explore the behavioral influences in terms of movements in people confronted with virtual reality scenes of extreme heights and develop an acrophobia classification model based on human movement characteristics. To this end, we used wireless miniaturized inertial navigation sensors (WMINS) network to obtain the information of limb movements in the virtual environment. Based on these data, we constructed a series of data feature processing processes, proposed a system model for the classification of acrophobia and non-acrophobia based on human motion feature analysis, and realized the classification recognition of acrophobia and non-acrophobia through the designed integrated learning model. The final accuracy of acrophobia dichotomous classification based on limb motion information reached 94.64%, which has higher accuracy and efficiency compared with other existing research models. Overall, our study demonstrates a strong correlation between people's mental state during fear of heights and their limb movements at that time.
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Affiliation(s)
- Xiankai Cheng
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Benkun Bao
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Weidong Cui
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Shuai Liu
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Jun Zhong
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Liming Cai
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Hongbo Yang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
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Fischer OM, Missen KJ, Tokuno CD, Carpenter MG, Adkin AL. Postural threat increases sample entropy of postural control. Front Neurol 2023; 14:1179237. [PMID: 37342783 PMCID: PMC10277644 DOI: 10.3389/fneur.2023.1179237] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 05/12/2023] [Indexed: 06/23/2023] Open
Abstract
Introduction Postural threat elicits modifications to standing balance. However, the underlying neural mechanism(s) responsible remain unclear. Shifts in attention focus including directing more attention to balance when threatened may contribute to the balance changes. Sample entropy, a measure of postural sway regularity with lower values reflecting less automatic and more conscious control of balance, may support attention to balance as a mechanism to explain threat-induced balance changes. The main objectives were to investigate the effects of postural threat on sample entropy, and the relationships between threat-induced changes in physiological arousal, perceived anxiety, attention focus, sample entropy, and traditional balance measures. A secondary objective was to explore if biological sex influenced these relationships. Methods Healthy young adults (63 females, 42 males) stood quietly on a force plate without (No Threat) and with (Threat) the expectation of receiving a postural perturbation (i.e., forward/backward support surface translation). Mean electrodermal activity and anterior-posterior centre of pressure (COP) sample entropy, mean position, root mean square, mean power frequency, and power within low (0-0.05 Hz), medium (0.5-1.8 Hz), and high-frequency (1.8-5 Hz) components were calculated for each trial. Perceived anxiety and attention focus to balance, task objectives, threat-related stimuli, self-regulatory strategies, and task-irrelevant information were rated after each trial. Results and Discussion Significant threat effects were observed for all measures, except low-frequency sway. Participants were more physiologically aroused, more anxious, and directed more attention to balance, task objectives, threat-related stimuli, and self-regulatory strategies, and less to task-irrelevant information in the Threat compared to No Threat condition. Participants also increased sample entropy, leaned further forward, and increased the amplitude and frequency of COP displacements, including medium and high-frequency sway, when threatened. Males and females responded in the same way when threatened, except males had significantly larger threat-induced increases in attention to balance and high-frequency sway. A combination of sex and threat-induced changes in physiological arousal, perceived anxiety, and attention focus accounted for threat-induced changes in specific traditional balance measures, but not sample entropy. Increased sample entropy when threatened may reflect a shift to more automatic control. Directing more conscious control to balance when threatened may act to constrain these threat-induced automatic changes to balance.
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Affiliation(s)
- Olivia M. Fischer
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Kyle J. Missen
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Craig D. Tokuno
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Mark G. Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Allan L. Adkin
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
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Hodgson DD, King JA, Darici O, Dalton BH, Cleworth TW, Cluff T, Peters RM. Visual feedback-dependent modulation of arousal, postural control, and muscle stretch reflexes assessed in real and virtual environments. Front Hum Neurosci 2023; 17:1128548. [PMID: 37082148 PMCID: PMC10110857 DOI: 10.3389/fnhum.2023.1128548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 03/14/2023] [Indexed: 04/07/2023] Open
Abstract
IntroductionThe mechanisms regulating neuromuscular control of standing balance can be influenced by visual sensory feedback and arousal. Virtual reality (VR) is a cutting-edge tool for probing the neural control of balance and its dependence on visual feedback, but whether VR induces neuromodulation akin to that seen in real environments (eyes open vs. closed or ground level vs. height platform) remains unclear.MethodsHere we monitored 20 healthy young adults (mean age 23.3 ± 3.2 years; 10 females) during four conditions of quiet standing. Two real world conditions (eyes open and eyes closed; REO and REC) preceded two eyes-open virtual ‘low’ (ground level; VRL) and ‘high’ (14 m height platform; VRH) conditions. We measured arousal via electrodermal activity and psychosocial questionnaires rating perceived fear and anxiety. We recorded surface electromyography over the right soleus, medial gastrocnemius, and tibialis anterior, and performed force plate posturography. As a proxy for modulations in neural control, we assessed lower limb reflexive muscle responses evoked by tendon vibration and electrical stimulation.ResultsPhysiological and perceptual indicators of fear and anxiety increased in the VRH condition. Background soleus muscle activation was not different across conditions; however, significant increases in muscle activity were observed for medial gastrocnemius and tibialis anterior in VRH relative to REO. The mean power frequency of postural sway also increased in the VRH condition relative to REO. Finally, with a fixed stimulus level across conditions, mechanically evoked reflexes remained constant, while H-reflex amplitudes decreased in strength within virtual reality.DiscussionNotably, H-reflexes were lower in the VRL condition than REO, suggesting that these ostensibly similar visual environments produce different states of reflexive balance control. In summary, we provide novel evidence that VR can be used to modulate upright postural control, but caution that standing balance in analogous real and virtual environments may involve different neural control states.
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Affiliation(s)
| | - Jordan A. King
- Biomedical Engineering, University of Calgary, Calgary, AB, Canada
| | - Osman Darici
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Brian H. Dalton
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | | | - Tyler Cluff
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Ryan M. Peters
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Biomedical Engineering, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- *Correspondence: Ryan M. Peters,
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Promsri A, Bangkomdet K, Jindatham I, Jenchang T. Leg Dominance—Surface Stability Interaction: Effects on Postural Control Assessed by Smartphone-Based Accelerometry. Sports (Basel) 2023; 11:sports11040075. [PMID: 37104149 PMCID: PMC10145104 DOI: 10.3390/sports11040075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 03/19/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
The preferential use of one leg over another in performing lower-limb motor tasks (i.e., leg dominance) is considered to be one of the internal risk factors for sports-related lower-limb injuries. The current study aimed to investigate the effects of leg dominance on postural control during unipedal balancing on three different support surfaces with increasing levels of instability: a firm surface, a foam pad, and a multiaxial balance board. In addition, the interaction effect between leg dominance and surface stability was also tested. To this end, a tri-axial accelerometer-based smartphone sensor was placed over the lumbar spine (L5) of 22 young adults (21.5 ± 0.6 years) to record postural accelerations. Sample entropy (SampEn) was applied to acceleration data as a measure of postural sway regularity (i.e., postural control complexity). The results show that leg dominance (p < 0.001) and interaction (p < 0.001) effects emerge in all acceleration directions. Specifically, balancing on the dominant (kicking) leg shows more irregular postural acceleration fluctuations (high SampEn), reflecting a higher postural control efficiency or automaticity than balancing on the non-dominant leg. However, the interaction effects suggest that unipedal balancing training on unstable surfaces is recommended to reduce interlimb differences in neuromuscular control for injury prevention and rehabilitation.
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Affiliation(s)
- Arunee Promsri
- Department of Physical Therapy, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand
- Unit of Excellence in Neuromechanics, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand
- Correspondence: ; Tel.: +66-54-466-666 (ext. 3817)
| | - Kotchakorn Bangkomdet
- Department of Physical Therapy, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand
| | - Issariya Jindatham
- Department of Physical Therapy, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand
| | - Thananya Jenchang
- Department of Physical Therapy, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand
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Gorrell LM, Conway PJ, Onasch F, Herzog W. Electromyographic Responses of Neck, Back, and Limb Outlet Muscles Associated With High-Velocity, Low-Amplitude Manual Cervical and Upper Thoracic Spinal Manipulation of Individuals With Mild Neck Disability: A Descriptive Observational Investigation. J Manipulative Physiol Ther 2022; 45:33-44. [PMID: 35753874 DOI: 10.1016/j.jmpt.2022.03.018] [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: 08/20/2020] [Revised: 03/18/2022] [Accepted: 03/18/2022] [Indexed: 10/17/2022]
Abstract
OBJECTIVES The purpose of this study was to investigate the extent of electromyographic responses associated with manual high-velocity, low-amplitude (HVLA) spinal manipulation systematically applied to the upper and lower cervical and upper thoracic spines in a cohort with mild neck disability. METHODS The study was a descriptive observational investigation, with all participants receiving the same interventions. Nineteen participants with mild neck disability received 6 manual HVLA manipulations to the cervical and upper thoracic spine. Bipolar surface electromyography electrode pairs were used to measure responses of 16 neck, back, and limb outlet muscles bilaterally. The number of electromyographic responses was then calculated. RESULTS Electromyographic responses associated with cervical and thoracic manipulation occurred in a median of 4 of the 16 (range: 1-14) recorded muscles. Cervical spinal manipulation was associated with the highest rates of electromyographic responses in neck muscles, whereas responses in back muscles were highest after upper thoracic manipulation. CONCLUSION Cervical spinal manipulation was associated with the highest rate of electromyographic responses in muscles of the cervical spine (sternocleidomastoid and splenius cervicis), whereas responses in back muscles (upper and middle trapezius, latissimus dorsi, and longissimus thoracis) were highest after upper thoracic manipulations. This result suggests that electromyographic muscular responses associated with spinal manipulation primarily occur locally (close to the target segment) rather than distally.
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Affiliation(s)
- Lindsay M Gorrell
- Integrative Spinal Research Group, Department of Chiropractic Medicine, Balgrist University Hospital, Zurich, Switzerland; University of Zurich, Zurich, Switzerland.
| | | | - Franziska Onasch
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Castro P, Papoutselou E, Mahmoud S, Hussain S, Bassaletti CF, Kaski D, Bronstein A, Arshad Q. Priming overconfidence in belief systems reveals negative return on postural control mechanisms. Gait Posture 2022; 94:1-8. [PMID: 35189573 DOI: 10.1016/j.gaitpost.2022.02.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/01/2022] [Accepted: 02/13/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Modulation of postural control strategies and heightened perceptual ratings of instability when exposed to postural threats, illustrates the association between anxiety and postural control. RESEARCH QUESTION Here we test whether modulating prior expectations can engender postural-related anxiety which, in turn, may impair postural control and dissociate the well-established relationship between sway and subjective instability. METHODS We modulated expectations of the difficulty posed by an upcoming postural task via priming. In the visual priming condition, participants watched a video of an actor performing the task with either a stable or unstable performance, before themselves proceeding with the postural task. In the verbal priming paradigm, participants were given erroneous verbal information regarding the amplitude of the forthcoming platform movement, or no prior information. RESULTS Following the visual priming, the normal relationship between trunk sway and subjective instability was preserved only in those individuals that viewed the stable but not the unstable actor. In the verbal priming experiment we observed an increase in subjective instability and anxiety during task performance in individuals who were erroneously primed that sled amplitude would increase, when in fact it did not. SIGNIFICANCE Our findings show that people's subjective experiences of instability and anxiety during a balancing task are powerfully modulated by priming. The contextual provision of erroneous cognitive priors dissociates the normally 'hard wired' relationship between objective measures and subjective ratings of sway. Our findings have potential clinical significance for the development of enhanced cognitive retraining in patients with balance disorders, e.g. via modifying expectations.
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Affiliation(s)
- Patricia Castro
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK; Universidad del Desarrollo, Escuela de Fonoaudiología, Facultad de Medicina Clínica Alemana. Santiago, Chile; Departamento de Fonoaudiología, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Efstratia Papoutselou
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK
| | - Sami Mahmoud
- Fakultät für Medizin, Technische Universität München, München, Germany
| | - Shahvaiz Hussain
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK
| | | | - Diego Kaski
- Department of Clinical and Motor Neurosciences, Centre for Vestibular and Behavioural Neurosciences, University College London, London, UK
| | - Adolfo Bronstein
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK.
| | - Qadeer Arshad
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London, UK; inAmind Laboratory, Department of Neuroscience, Psychology and Behaviour, University of Leicester, University Road, Leicester LE1 7RH, UK.
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Nielsen EI, Cleworth TW, Carpenter MG. Exploring emotional-modulation of visually evoked postural responses through virtual reality. Neurosci Lett 2022; 777:136586. [PMID: 35331814 DOI: 10.1016/j.neulet.2022.136586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/08/2022] [Accepted: 03/18/2022] [Indexed: 11/19/2022]
Abstract
Exposure to postural threat has been documented to influence the sensory contributions of proprioceptive and vestibular information in standing balance control. Contributions from the visual system to balance are also crucial, yet the degree to which postural threat may modulate visual control of balance is not well characterized. Therefore, the aims of this study were to assess the feasibility of eliciting visual evoked postural responses (VEPRs) using head-mounted virtual reality (VR) and use this method to examine the potential influence of virtual postural threat on the visual control of balance. 36 healthy young adults were exposed to a pseudorandom, translational visual stimulus of a real-world environment in VR. The visual stimulus was presented in virtual conditions of LOW and HIGH postural threat in which participants stood at ground level, and on a 7m elevated platform, respectively. VEPRs were successfully produced in both postural threat conditions. When exposed to the visual stimulus while at an elevated surface height, participants demonstrated significant changes to their physiological arousal and emotional state. Despite significant coherence across the stimulus' frequency range, stimulus correlated VEPRs were not significantly modulated during exposure to the visual stimulus under virtual postural threat. This study supports the future utility of VR head-mounted displays in examining emotional influences on the visual control of balance.
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Affiliation(s)
- Emma I Nielsen
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Taylor W Cleworth
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada.
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11
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EEG based cortical investigation for the limit of stability analysis in transfemoral amputees: A comparison with able-bodied individuals. Biocybern Biomed Eng 2022. [DOI: 10.1016/j.bbe.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Zaback M, Adkin AL, Chua R, Timothy Inglis J, Carpenter MG. Facilitation and habituation of cortical and subcortical control of standing balance following repeated exposure to a height-related postural threat. Neuroscience 2022; 487:8-25. [DOI: 10.1016/j.neuroscience.2022.01.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 12/23/2021] [Accepted: 01/17/2022] [Indexed: 01/21/2023]
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Impairment of Proprioception in Young Adult Nonradicular Patients with Lumbar Derangement Syndrome. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5550257. [PMID: 34660792 PMCID: PMC8516538 DOI: 10.1155/2021/5550257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 08/17/2021] [Accepted: 09/07/2021] [Indexed: 11/17/2022]
Abstract
Maintaining body balance is a complex function based on the information deriving from the vestibular, visual, and proprioceptive systems. The aim of the study was to evaluate quiet single stance stability in young adults with lumbar derangement syndrome (LDS) and in the control group of the healthy subjects. The second aim of this study was to determine whether pain intensity, degree of disability, and the level of physical activity can influence postural control in patients with LDS. It is important to underline that selecting a homogeneous group of LBP patients using, for example, mechanical diagnosis and therapy method and Quebec Task Force Classification, can result in an increased sensitivity of the study. The study included 126 subjects: 70 patients with LDS (37 women, 33 men) and the control group 56 healthy volunteers (36 women, 20 men). In case of multiple group comparisons for variables with normal distribution, ANOVA post hoc test was used or, as the nonparametric equivalent, Kruskal-Wallis test. In all these calculations, the statistical significance level was set to p < 0.05. The stability index eyes open for the study group was 88.34 and for the control group 89.86. There was no significant difference in the level of postural control between the study and control groups (p > 0.05). The level of stability index eyes closed (SI EC) for the study group was 71.44 and for the control group 77.1. SI EC results showed significant differences in proprioceptive control during single leg stance between the study and control groups (p < 0.05). The level of pain intensity, the degree of disability, and physical activity level did not influence postural control in the study group with LDS. In summary, patients with LDS showed significantly worse proprioceptive control.
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14
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Anxiety does not always affect balance: the predominating role of cognitive engagement in a video gaming task. Exp Brain Res 2021; 239:2001-2014. [PMID: 33909113 DOI: 10.1007/s00221-021-06104-w] [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: 01/30/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Scientists have predominantly assessed anxiety's impact on postural control when anxiety is created by the need to maintain balance (e.g., standing at heights). In the present study, we investigate how postural control and its mechanisms (i.e., vestibular function) are impacted when anxiety is induced by an unrelated task (playing a video game). Additionally, we compare watching and playing a game to dissociate postural adaptations caused by increased engagement rather than anxiety. Participants [N = 25, female = 8, M (SD) age = 23.5 (3.9)] held a controller in four standing conditions of varying surface compliance (firm or foam) and with or without peripheral visual occlusion across four blocks: quiet standing (baseline), watching the game with a visual task (watching), playing the game (low anxiety), and playing under anxiety (high anxiety). We measured sway area, sway frequency, root mean square (RMS) sway, anxiety, and mental effort. Limited sway differences emerged between anxiety blocks (only sway area on firm surface). The watching block elicited more sway than baseline (greater sway area and RMS sway; lower sway frequency), and the low anxiety block elicited more sway than the watching block (greater sway area and RMS sway; higher sway frequency). Mental effort was associated with increased sway area and RMS sway. Our findings indicate that anxiety, when generated through competition, has minimal impact on postural control. Postural control primarily adapts according to mental effort and more cognitively engaging task constraints (i.e., playing versus watching). We speculate increased sway reflects the prioritization of attention to game performance over postural control.
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15
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Zaback M, Luu MJ, Adkin AL, Carpenter MG. Selective preservation of changes to standing balance control despite psychological and autonomic habituation to a postural threat. Sci Rep 2021; 11:384. [PMID: 33431937 PMCID: PMC7801693 DOI: 10.1038/s41598-020-79417-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/30/2020] [Indexed: 01/29/2023] Open
Abstract
Humans exhibit changes in postural control when confronted with threats to stability. This study used a prolonged threat exposure protocol to manipulate emotional state within a threatening context to determine if any threat-induced standing behaviours are employed independent of emotional state. Retention of balance adaptations was also explored. Thirty-seven adults completed a series of 90-s standing trials at two surface heights (LOW: 0.8 m above ground, away from edge; HIGH: 3.2 m above ground, at edge) on two visits 2-4 weeks apart. Psychological and autonomic state was assessed using self-report and electrodermal measures. Balance control was assessed using centre of pressure (COP) and lower limb electromyographic recordings. Upon initial threat exposure, individuals leaned backward, reduced low-frequency centre of pressure (COP) power, and increased high-frequency COP power and plantar/dorsiflexor coactivation. Following repeated exposure, the psychological and autonomic response to threat was substantially reduced, yet only high-frequency COP power and plantar/dorsiflexor coactivation habituated. Upon re-exposure after 2-4 weeks, there was partial recovery of the emotional response to threat and few standing balance adaptations were retained. This study suggests that some threat-induced standing behaviours are coupled with the psychological and autonomic state changes induced by threat, while others may reflect context-appropriate adaptations resistant to habituation.
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Affiliation(s)
- Martin Zaback
- grid.17091.3e0000 0001 2288 9830School of Kinesiology, University of British Columbia, 6108 Thunderbird Blvd., Vancouver, BC V6T 1Z4 Canada
| | - Minh John Luu
- grid.17091.3e0000 0001 2288 9830School of Kinesiology, University of British Columbia, 6108 Thunderbird Blvd., Vancouver, BC V6T 1Z4 Canada
| | - Allan L. Adkin
- grid.411793.90000 0004 1936 9318Department of Kinesiology, Brock University, St. Catharines, ON Canada
| | - Mark G. Carpenter
- grid.17091.3e0000 0001 2288 9830School of Kinesiology, University of British Columbia, 6108 Thunderbird Blvd., Vancouver, BC V6T 1Z4 Canada ,grid.17091.3e0000 0001 2288 9830Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC Canada ,grid.17091.3e0000 0001 2288 9830International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC Canada
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16
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Goldstein Ferber S, Shoval G, Zalsman G, Mikulincer M, Weller A. Between Action and Emotional Survival During the COVID-19 era: Sensorimotor Pathways as Control Systems of Transdiagnostic Anxiety-Related Intolerance to Uncertainty. Front Psychiatry 2021; 12:680403. [PMID: 34393847 PMCID: PMC8358206 DOI: 10.3389/fpsyt.2021.680403] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 06/16/2021] [Indexed: 12/29/2022] Open
Abstract
Objectives: The COVID-19 pandemic and aligned social and physical distancing regulations increase the sense of uncertainty, intensifying the risk for psychopathology globally. Anxiety disorders are associated with intolerance to uncertainty. In this review we describe brain circuits and sensorimotor pathways involved in human reactions to uncertainty. We present the healthy mode of coping with uncertainty and discuss deviations from this mode. Methods: Literature search of PubMed and Google Scholar. Results: As manifestation of anxiety disorders includes peripheral reactions and negative cognitions, we suggest an integrative model of threat cognitions modulated by sensorimotor regions: "The Sensorimotor-Cognitive-Integration-Circuit." The model emphasizes autonomic nervous system coupling with the cortex, addressing peripheral anxious reactions to uncertainty, pathways connecting cortical regions and cost-reward evaluation circuits to sensorimotor regions, filtered by the amygdala and basal ganglia. Of special interest are the ascending and descending tracts for sensory-motor crosstalk in healthy and pathological conditions. We include arguments regarding uncertainty in anxiety reactions to the pandemic and derive from our model treatment suggestions which are supported by scientific evidence. Our model is based on systematic control theories and emphasizes the role of goal conflict regulation in health and pathology. We also address anxiety reactions as a spectrum ranging from healthy to pathological coping with uncertainty, and present this spectrum as a transdiagnostic entity in accordance with recent claims and models. Conclusions: The human need for controllability and predictability suggests that anxiety disorders reactive to the pandemic's uncertainties reflect pathological disorganization of top-down bottom-up signaling and neural noise resulting from non-pathological human needs for coherence in life.
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Affiliation(s)
- Sari Goldstein Ferber
- Psychology Department and Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Gal Shoval
- Geha Mental Health Center, Petah Tiqva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Princeton Neuroscience Institute, Princeton University, Princeton, NJ, United States
| | - Gil Zalsman
- Geha Mental Health Center, Petah Tiqva, Israel.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Division of Molecular Imaging and Neuropathology, Department of Psychiatry, Columbia University and New York State Psychiatric Institute, New York, NY, United States
| | - Mario Mikulincer
- Interdisciplinary Center (IDC) Herzliya, Baruch Ivcher School of Psychology, Herzliya, Israel
| | - Aron Weller
- Psychology Department and Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
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17
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The intensity of awake bruxism episodes is increased in individuals with high trait anxiety. Clin Oral Investig 2020; 25:3197-3206. [PMID: 33098032 DOI: 10.1007/s00784-020-03650-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 10/16/2020] [Indexed: 01/31/2023]
Abstract
OBJECTIVES Trait anxiety is associated with an increased occurrence of awake bruxism episodes, a behavior characterized by clenching of the teeth contributing to temporomandibular disorders in some individuals. Here we measured the activity of the masseter and the intensity and duration of spontaneous wake-time tooth clenching episodes in healthy individuals with different levels of trait anxiety (TA). MATERIALS AND METHODS Two hundred fifty-five individuals completed a web survey. Using their TA scores, we allocated them in low (< 20th percentile of the TA score distribution), intermediate (between 20th and 80th ), and high (> 80th) TA groups. We analyzed the electromyographic (EMG) activity of the right masseter during a 15-min silent reading task in forty-three individuals with low (n = 12), intermediate (n = 17), and high TA (n = 14). We tested between-group differences in EMG activity of the masseter, as well as postural activity-the muscular activity that maintains mandibular posture, and amplitude and duration of spontaneous tooth clenching episodes. RESULTS The activity of the masseter (mean ± SEM %maximum voluntary contraction/MVC) was greater in the high TA (10.23 ± 0.16%MVC) than the intermediate (8.49 ± 0.16%MVC) and low (7.97 ± 0.22%MVC) TA groups (all p < 0.001). Postural activity did not differ between groups (all p > 0.05). The EMG amplitude of tooth clenching episodes was greater in the high TA (19.97 ± 0.21 %MVC) than the intermediate (16.40 ± 0.24%MVC) and low (15.48 ± 0.38 %MVC) TA groups (all p < 0.05). The cumulative duration of clenching episodes was not different between groups (p = 0.390). CONCLUSIONS Increased TA is associated with both increased masseter muscle activity and intensity of wake-time tooth clenching episodes. CLINICAL RELEVANCE TA may contribute significantly to masticatory muscle overload.
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18
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Cyma-Wejchenig M, Maciaszek J, Marciniak K, Stemplewski R. The Effects of Cognitive Task and Change of Height on Postural Stability and Cardiovascular Stress in Workers Working at Height. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E6541. [PMID: 32911804 PMCID: PMC7560234 DOI: 10.3390/ijerph17186541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/05/2020] [Accepted: 09/05/2020] [Indexed: 01/07/2023]
Abstract
The purpose of the study was to analyze the effects of cognitive task and change of height on the postural stability and cardiovascular stress of at-height workers. The study included 32 healthy men aged 25-47. Due to the type of work performed, two groups were identified: at‒height workers, HW (n = 16), and office workers (mainly work at desk with a computer) OW (n = 16). The objective measures of postural stability (posturography) and cardiovascular stress (heart rate monitor) were evaluated for both groups at two different platform heights (ground level and 1 m above the ground) with or without cognitive task (backward counting). The increased height and the cognitive task were found to significantly affect measures of postural stability and cardiovascular stress. It was observed that in inexperienced OW employees, higher platform height and performing a cognitive task meant that posture stability significantly decreased, while cardiovascular stress and difficulties in maintaining balance increased. In HW group postural stability is less affected by distress conditions than in OW group.
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Affiliation(s)
- Magdalena Cyma-Wejchenig
- Department of Physical Activity and Health Promotion Science, Poznan University of Physical Education, 61-871 Poznan, Poland; (J.M.); (K.M.); (R.S.)
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19
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Promsri A, Haid T, Federolf P. Complexity, Composition, and Control of Bipedal Balancing Movements as the Postural Control System Adapts to Unstable Support Surfaces or Altered Feet Positions. Neuroscience 2020; 430:113-124. [DOI: 10.1016/j.neuroscience.2020.01.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/14/2020] [Accepted: 01/19/2020] [Indexed: 10/25/2022]
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20
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Promsri A, Haid T, Werner I, Federolf P. Leg Dominance Effects on Postural Control When Performing Challenging Balance Exercises. Brain Sci 2020; 10:E128. [PMID: 32106392 PMCID: PMC7139434 DOI: 10.3390/brainsci10030128] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 01/29/2023] Open
Abstract
Leg dominance reflects the preferential use of one leg over another and is typically attributed to asymmetries in the neural circuitry. Detecting leg dominance effects on motor behavior, particularly during balancing exercises, has proven difficult. The current study applied a principal component analysis (PCA) on kinematic data, to assess bilateral asymmetry on the coordinative structure (hypothesis H1) or on the control characteristics of specific movement components (hypothesis H2). Marker-based motion tracking was performed on 26 healthy adults (aged 25.3 ± 4.1 years), who stood unipedally on a multiaxial unstable board, in a randomized order, on their dominant and non-dominant leg. Leg dominance was defined as the kicking leg. PCA was performed to determine patterns of correlated segment movements ("principal movements" PMks). The control of each PMk was characterized by assessing its acceleration (second-time derivative). Results were inconclusive regarding a leg-dominance effect on the coordinative structure of balancing movements (H1 inconclusive); however, different control (p = 0.005) was observed in PM3, representing a diagonal plane movement component (H2 was supported). These findings supported that leg dominance effects should be considered when assessing or training lower-limb neuromuscular control and suggest that specific attention should be given to diagonal plane movements.
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Affiliation(s)
- Arunee Promsri
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria; (A.P.); (T.H.); (I.W.)
- Department of Physical Therapy, University of Phayao, Phayao 56000, Thailand
| | - Thomas Haid
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria; (A.P.); (T.H.); (I.W.)
| | - Inge Werner
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria; (A.P.); (T.H.); (I.W.)
| | - Peter Federolf
- Department of Sport Science, University of Innsbruck, Innsbruck 6020, Austria; (A.P.); (T.H.); (I.W.)
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21
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Zaback M, Adkin AL, Carpenter MG. Adaptation of emotional state and standing balance parameters following repeated exposure to height-induced postural threat. Sci Rep 2019; 9:12449. [PMID: 31462652 PMCID: PMC6713771 DOI: 10.1038/s41598-019-48722-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/07/2019] [Indexed: 11/12/2022] Open
Abstract
Height-induced postural threat influences standing balance control. However, it is unknown if minimizing individuals’ emotional response to threat moderates this relationship. This study repeatedly exposed individuals to height-induced postural threat to determine if reducing the emotional response to threat influences standing balance control. Sixty-eight young adults completed a series of standing trials at LOW (0.8 m above ground, away from edge) and HIGH (3.2 m above ground, at edge) postural threat conditions. Emotional state was assessed using self-report and electrodermal measures. Standing balance was assessed through analysis of centre of pressure (COP) movement and lower leg electromyographic activity. Individuals’ emotional response to threat was attenuated following repeated threat exposure. However, threat-induced changes in standing balance were largely preserved. When initially threatened, individuals leaned backward and demonstrated smaller amplitude and higher frequency of COP adjustments; these balance outcomes did not change following repeated threat exposure. Only high frequency COP oscillations (>1.8 Hz) and ankle muscle co-contraction showed any adaptation; regression analyses showed that these behavioural adaptations were accounted for by a combination of emotional and cognitive state changes. This suggests that some threat-induced standing balance changes are more closely linked with the emotional response to threat than others, and are therefore amendable to intervention.
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Affiliation(s)
- Martin Zaback
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Allan L Adkin
- Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada. .,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada. .,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada.
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22
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Roussiez V, Van Cant J. Predisposing factors to hamstring neuromuscular deficits—implications for prevention and rehabilitation of hamstring strain injuries: a narrative review. PHYSICAL THERAPY REVIEWS 2019. [DOI: 10.1080/10833196.2019.1616375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Vincent Roussiez
- Department of Physical Therapy, Institut Parnasse-ISEI, Brussels, Belgium
| | - Joachim Van Cant
- Department of Physical Therapy, Institut Parnasse-ISEI, Brussels, Belgium
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23
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Müller UWD, Witteman CLM, Spijker J, Alpers GW. All's Bad That Ends Bad: There Is a Peak-End Memory Bias in Anxiety. Front Psychol 2019; 10:1272. [PMID: 31249540 PMCID: PMC6582762 DOI: 10.3389/fpsyg.2019.01272] [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: 01/21/2019] [Accepted: 05/14/2019] [Indexed: 11/29/2022] Open
Abstract
The peak-end memory bias has been well documented for the retrospective evaluation of pain. It describes that the retrospective evaluation of pain is largely based on the discomfort experienced at the most intense point (peak) and at the end of the episode. This is notable because it means that longer episodes with a better ending can be remembered as less aversive than shorter ones; this is even if the former had the same peak in painfulness and an overall longer duration of pain. Until now, this bias has not been studied in the domain of anxiety despite the high relevance of variable levels of anxiety in the treatment of anxiety disorders. Therefore, we set out to replicate the original studies but with an induction of variable levels of anxiety. Of 64 women, half watched a clip from a horror movie which ended at the most frightening moment. The other half watched an extended version of this clip with a moderately frightening ending. Afterward, all participants were asked to rate the global anxiety which was elicited by the video. When the film ended at the most frightening moment, participants retrospectively reported more anxiety than participants who watched the extended version. This is the first study to document that the peak-end bias can be found in the domain of anxiety. These findings require replication and extension to a treatment context to evaluate its implications for exposure therapy.
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Affiliation(s)
- Ulrich W D Müller
- Department of Psychology, School of Social Sciences, University of Mannheim, Mannheim, Germany.,Behavioural Science Institute, Radboud University, Nijmegen, Netherlands
| | - Cilia L M Witteman
- Behavioural Science Institute, Radboud University, Nijmegen, Netherlands
| | - Jan Spijker
- Behavioural Science Institute, Radboud University, Nijmegen, Netherlands
| | - Georg W Alpers
- Department of Psychology, School of Social Sciences, University of Mannheim, Mannheim, Germany
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24
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Liu X, Rosendo A, Ikemoto S, Shimizu M, Hosoda K. Robotic investigation on effect of stretch reflex and crossed inhibitory response on bipedal hopping. J R Soc Interface 2019; 15:rsif.2018.0024. [PMID: 29593088 PMCID: PMC5908536 DOI: 10.1098/rsif.2018.0024] [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: 01/10/2018] [Accepted: 03/02/2018] [Indexed: 12/15/2022] Open
Abstract
To maintain balance during dynamic locomotion, the effects of proprioceptive sensory feedback control (e.g. reflexive control) should not be ignored because of its simple sensation and fast reaction time. Scientists have identified the pathways of reflexes; however, it is difficult to investigate their effects during locomotion because locomotion is controlled by a complex neural system and current technology does not allow us to change the control pathways in living humans. To understand these effects, we construct a musculoskeletal bipedal robot, which has similar body structure and dynamics to those of a human. By conducting experiments on this robot, we investigate the effects of reflexes (stretch reflex and crossed inhibitory response) on posture during hopping, a simple and representative bouncing gait with complex dynamics. Through over 300 hopping trials, we confirm that both the stretch reflex and crossed response can contribute to reducing the lateral inclination during hopping. These reflexive pathways do not use any prior knowledge of the dynamic information of the body such as its inclination. Beyond improving the understanding of the human neural system, this study provides roboticists with biomimetic ideas for robot locomotion control.
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Affiliation(s)
- Xiangxiao Liu
- Graduate School of Engineering Science, Osaka University, Japan
| | - Andre Rosendo
- Graduate School of Engineering Science, Osaka University, Japan
| | - Shuhei Ikemoto
- Graduate School of Engineering Science, Osaka University, Japan
| | | | - Koh Hosoda
- Graduate School of Engineering Science, Osaka University, Japan
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25
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Postural Threat Modulates Perceptions of Balance-Related Movement During Support Surface Rotations. Neuroscience 2019; 404:413-422. [DOI: 10.1016/j.neuroscience.2019.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/02/2019] [Accepted: 02/09/2019] [Indexed: 11/20/2022]
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26
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Miroshnichenko GG, Meigal AY, Saenko IV, Gerasimova-Meigal LI, Chernikova LA, Subbotina NS, Rissanen SM, Karjalainen PA. Parameters of Surface Electromyogram Suggest That Dry Immersion Relieves Motor Symptoms in Patients With Parkinsonism. Front Neurosci 2018; 12:667. [PMID: 30319343 PMCID: PMC6168649 DOI: 10.3389/fnins.2018.00667] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 09/05/2018] [Indexed: 11/13/2022] Open
Abstract
Dry immersion (DI) is acknowledged as a reliable space flight analog condition. At DI, subject is immersed in water being wrapped in a waterproof film to imitate microgravity (μG). Microgravity is known to decrease muscle tone due to deprivation of the sensory stimuli that activate the reflexes that keep up the muscle tone. In contrary, parkinsonian patients are characterized by elevated muscle tone, or rigidity, along with rest tremor and akinesia. We hypothesized that DI can diminish the elevated muscle tone and/or the tremor in parkinsonian patients. Fourteen patients with Parkinson's disease (PD, 10 males, 4 females, 47-73 years) and 5 patients with vascular parkinsonism (VP, 1 male, 4 females, 65-72 years) participated in the study. To evaluate the effect of DI on muscles' functioning, we compared parameters of surface electromyogram (sEMG) measured before and after a single 45-min long immersion session. The sEMG recordings were made from the biceps brachii muscle, bilaterally. Each recording was repeated with the following loading conditions: with arms hanging freely down, and with 0, 1, and 2 kg loading on each hand with elbows flexed to 90°. The sEMG parameters comprised of amplitude, median frequency, time of decay of mutual information, sample entropy, correlation dimension, recurrence rate, and determinism of sEMG. These parameters have earlier been proved to be sensitive to PD severity. We used the Wilcoxon test to decide which parameters were statistically significantly different before and after the dry immersion. Accepting the p < 0.05 significance level, amplitude, time of decay of mutual information, recurrence rate, and determinism tended to decrease, while median frequency and sample entropy of sEMG tended to increase after the DI. The most statistically significant change was for the determinism of sEMG from the left biceps with 1 kg loading, which decreased for 84% of the patients. The results suggest that DI can promptly relieve motor symptoms of parkinsonism. We conclude that DI has strong potential as a rehabilitation method for parkinsonian patients.
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Affiliation(s)
- German G Miroshnichenko
- Biosignal Analysis and Medical Imaging Group, Department of Applied Physics, Faculty of Science and Forestry, University of Eastern Finland, Kuopio, Finland
| | - Alexander Yu Meigal
- Laboratory for Novel Methods in Physiology, Institute of High-Tech Biomedical Solutions, Petrozavodsk State University, Petrozavodsk, Russia
| | - Irina V Saenko
- Laboratory of Gravitational Physiology of Sensorimotor System, Department of Sensorimotor Physiology and Countermeasure, Institute of BioMedical Problems, Russian Academy of Sciences, Moscow, Russia
| | - Liudmila I Gerasimova-Meigal
- Department of Human and Animal Physiology, Physiopathology, Histology, Petrozavodsk State University, Petrozavodsk, Russia
| | - Liudmila A Chernikova
- Department of Neurorehabilitation and Physiotherapy, Research Center of Neurology, Russian Academy of Medical Sciences, Moscow, Russia
| | - Natalia S Subbotina
- Department of Neurology, Psychiatry, and Microbiology, Petrozavodsk State University, Petrozavodsk, Russia
| | - Saara M Rissanen
- Biosignal Analysis and Medical Imaging Group, Department of Applied Physics, Faculty of Science and Forestry, University of Eastern Finland, Kuopio, Finland
| | - Pasi A Karjalainen
- Biosignal Analysis and Medical Imaging Group, Department of Applied Physics, Faculty of Science and Forestry, University of Eastern Finland, Kuopio, Finland
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27
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Horslen BC, Zaback M, Inglis JT, Blouin JS, Carpenter MG. Increased human stretch reflex dynamic sensitivity with height-induced postural threat. J Physiol 2018; 596:5251-5265. [PMID: 30176053 DOI: 10.1113/jp276459] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/31/2018] [Indexed: 01/16/2023] Open
Abstract
KEY POINTS Threats to standing balance (postural threat) are known to facilitate soleus tendon-tap reflexes, yet the mechanisms driving reflex changes are unknown. Scaling of ramp-and-hold dorsiflexion stretch reflexes to stretch velocity and amplitude were examined as indirect measures of changes to muscle spindle dynamic and static function with height-induced postural threat. Overall, stretch reflexes were larger with threat. Furthermore, the slope (gain) of the stretch-velocity vs. short-latency reflex amplitude relationship was increased with threat. These findings are interpreted as indirect evidence for increased muscle spindle dynamic sensitivity, independent of changes in background muscle activity levels, with a threat to standing balance. We argue that context-dependent scaling of stretch reflexes forms part of a multisensory tuning process where acquisition and/or processing of balance-relevant sensory information is continuously primed to facilitate feedback control of standing balance in challenging balance scenarios. ABSTRACT Postural threat increases soleus tendon-tap (t-) reflexes. However, it is not known whether t-reflex changes are a result of central modulation, altered muscle spindle dynamic sensitivity or combined spindle static and dynamic sensitization. Ramp-and-hold dorsiflexion stretches of varying velocities and amplitudes were used to examine velocity- and amplitude-dependent scaling of short- (SLR) and medium-latency (MLR) stretch reflexes as an indirect indicator of spindle sensitivity. t-reflexes were also performed to replicate previous work. In the present study, we examined the effects of postural threat on SLR, MLR and t-reflex amplitude, as well as SLR-stretch velocity scaling. Forty young-healthy adults stood with one foot on a servo-controlled tilting platform and the other on a stable surface. The platform was positioned on a hydraulic lift. Threat was manipulated by having participants stand in low (height 1.1 m; away from edge) then high (height 3.5 m; at the edge) threat conditions. Soleus stretch reflexes were recorded with surface electromyography and SLRs and MLRs were probed with fixed-amplitude variable-velocity stretches. t-reflexes were evoked with Achilles tendon taps using a linear motor. SLR, MLR and t-reflexes were 11%, 9.5% and 16.9% larger, respectively, in the high compared to low threat condition. In 22 out of 40 participants, SLR amplitude was correlated to stretch velocity at both threat levels. In these participants, the gain of the SLR-velocity relationship was increased by 36.1% with high postural threat. These findings provide new supportive evidence for increased muscle spindle dynamic sensitivity with postural threat and provide further support for the context-dependent modulation of human somatosensory pathways.
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Affiliation(s)
- Brian C Horslen
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Present address: Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA, USA
| | - Martin Zaback
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.,The Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, BC, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
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Adkin AL, Carpenter MG. New Insights on Emotional Contributions to Human Postural Control. Front Neurol 2018; 9:789. [PMID: 30298048 PMCID: PMC6160553 DOI: 10.3389/fneur.2018.00789] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/31/2018] [Indexed: 12/15/2022] Open
Abstract
It has been just over 20 years since the effects of height-induced threat on human postural control were first investigated. Raising the height of the support surface on which individuals stood increased the perceived consequences of instability and generated postural control changes. Since this initial work, converging evidence has accumulated supporting the efficacy of using height-induced threat to study the effects of emotions on postural control and confirming a direct influence of threat-related changes in arousal, anxiety, and fear of falling on all aspects of postural control, including standing, anticipatory, and reactive balance. In general, threat-related postural changes promote a greater physical safety margin while maintaining upright stance. We use the static balance literature to critically examine the current state of knowledge regarding: (1) the extent to which threat-related changes in postural control are sensitive to threat-related changes in emotions; (2) the underlying neurophysiological and cognitive mechanisms that may contribute to explaining the relationship between emotions and postural control; and (3) the generalizability of threat-related changes across different populations and types of threat. These findings have important implications for understanding the neuromechanisms that control healthy balance, and highlight the need to recognize the potential contributions of psychological and physiological factors to balance deficits associated with age or pathology. We conclude with a discussion of the practical significance of this research, its impact on improving diagnosis and treatment of postural control deficits, and potential directions for future research.
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Affiliation(s)
- Allan L Adkin
- Department of Kinesiology, Brock University, St. Catharines, ON, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
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Roitblat Y, Cleminson R, Kavin A, Schonberger E, Shterenshis M. Assessment of anxiety in adolescents involved in a study abroad program: a prospective study. Int J Adolesc Med Health 2017; 32:/j/ijamh.ahead-of-print/ijamh-2017-0101/ijamh-2017-0101.xml. [PMID: 29168962 DOI: 10.1515/ijamh-2017-0101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/20/2017] [Indexed: 11/15/2022]
Abstract
Objective The aim of the study was to measure the effects on levels of anxiety in healthy teenagers caused by a temporary change of country and school during a study abroad program. Methods In a prospective study we gathered the data from six anxiety level related tests on high school participants in a study abroad program (age 15-17, n = 364, M 172, F 192). These volunteer participants were divided into two separate groups: with self-reported elevated levels of anxiety (n = 111; YES-group) and with self-reported normal levels of anxiety (n = 253; NO-group). Two control groups of schoolchildren drawn from two local schools were used for comparison (n = 100 each). Three tests were subjective, i.e. self-fill-out tests. The next three tests were objective psychological or neurophysiological tests designed to estimate reflex control, concentration and a feeling for the passage of time. Results The initial mean anxiety level score among the 364 participants was 41.5 ± 16.7 (min 16, max 80) on 5-110 scale. For the YES-group the score was 56.5 ± 15.9, and for the NO-group the score was 34.7 ± 17.4 (p = 0.05). The retesting after they had been in the same place for 7 weeks revealed that the mean anxiety level score of the participants decreased to 37.4 ± 16.9 (min 15, max 72). For the YES-group the score significantly decreased to 39.3 ± 15.5, and for the NO-group the score slightly elevated to 36.7 ± 16.4 producing similar results for both groups (p = 0.81). Conclusion A temporary change of country and school at first results in a rise in anxiety levels in about one third of participants. However, after an extended stay it falls to normal levels.
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Affiliation(s)
- Yulia Roitblat
- Department of Sciences, Yohana Jabotinsky Youth Town for Sciences and Arts Six Year Comprehensive School, Beer Yakov, Israel
| | - Ryan Cleminson
- Department of Psychology, Mount Moriah College, Sydney, Australia
| | - Aaron Kavin
- Department of Psychology, Mount Moriah College, Sydney, Australia
| | - Edan Schonberger
- Department of Psychology, Mount Moriah College, Sydney, Australia
| | - Michael Shterenshis
- Department of Sciences, Alexander Muss High School in Israel (AMHSI) affiliated to Alexander Muss Institute for Israel Education (AMIIE), Hod HaSharon, Israel.,AMHSI, 8/6 Shivat Zion Street, Rishon LeZion 7534141, Israel, Phone: 97254-337-9865
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30
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Cognitively and socially induced stress affects postural control. Exp Brain Res 2017; 236:305-314. [PMID: 29138872 DOI: 10.1007/s00221-017-5128-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/08/2017] [Indexed: 10/18/2022]
Abstract
Postural control is an adaptive process that can be affected by many aspects of human behavior, including emotional contexts. The main emotional contexts that affect postural control are postural threat and passive viewing of aversive or threatening images, both of which produce a reduction in postural sway. The aim of the present study was to assess whether similar stress-related changes in postural sway can be observed using stress induced by social evaluative threat (SET) while performing arithmetic tasks. Twelve young adults performed an arithmetic and a postural control task separately, concurrently, and concurrently with added time pressure in the arithmetic task. In the final condition, participants were given negative feedback about their performance in the arithmetic task and performed it again while being observed (SET condition). Results showed that stress increased linearly with task demand. Postural sway and reaction times were not affected by the first two conditions; however, when time pressure was introduced, reaction times became faster and sway amplitude increased. Finally, introduction of SET caused the predicted reduction in postural sway and an increase in reaction times relative to the time pressure condition. Our results suggest that stress induced using a combination of arithmetic tasks and social evaluative threat leads to systematic changes in postural control. The paradigm developed in the present study would be very useful in assessing interactions between cognition, stress, and postural control in the context of postural instability and falls in older adults.
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Prochazka A. Neurophysiology and neural engineering: a review. J Neurophysiol 2017; 118:1292-1309. [PMID: 28566462 PMCID: PMC5558026 DOI: 10.1152/jn.00149.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 12/19/2022] Open
Abstract
Neurophysiology is the branch of physiology concerned with understanding the function of neural systems. Neural engineering (also known as neuroengineering) is a discipline within biomedical engineering that uses engineering techniques to understand, repair, replace, enhance, or otherwise exploit the properties and functions of neural systems. In most cases neural engineering involves the development of an interface between electronic devices and living neural tissue. This review describes the origins of neural engineering, the explosive development of methods and devices commencing in the late 1950s, and the present-day devices that have resulted. The barriers to interfacing electronic devices with living neural tissues are many and varied, and consequently there have been numerous stops and starts along the way. Representative examples are discussed. None of this could have happened without a basic understanding of the relevant neurophysiology. I also consider examples of how neural engineering is repaying the debt to basic neurophysiology with new knowledge and insight.
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Affiliation(s)
- Arthur Prochazka
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
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32
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Doumas M. Mechanisms of postural threat: the Achilles heel of postural control? J Physiol 2017; 595:4129. [PMID: 28459135 DOI: 10.1113/jp274367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Michail Doumas
- School of Psychology, Faculty of Engineering and Physical Sciences, Queen's University Belfast, Belfast, UK
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Horslen BC, Inglis JT, Blouin JS, Carpenter MG. Both standing and postural threat decrease Achilles' tendon reflex inhibition from tendon electrical stimulation. J Physiol 2017; 595:4493-4506. [PMID: 28326567 DOI: 10.1113/jp273935] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/15/2017] [Indexed: 02/03/2023] Open
Abstract
KEY POINTS Golgi tendon organs (GTOs) and associated Ib reflexes contribute to standing balance, but the potential impacts of threats to standing balance on Ib reflexes are unknown. Tendon electrical stimulation to the Achilles' tendon was used to probe changes in Ib inhibition in medial gastrocnemius with postural orientation (lying prone vs. upright standing; experiment 1) and height-induced postural threat (standing at low and high surface heights; experiment 2). Ib inhibition was reduced while participants stood upright, compared to lying prone (42.2%); and further reduced when standing in the high, compared to low, threat condition (32.4%). These experiments will impact future research because they demonstrate that tendon electrical stimulation can be used to probe Ib reflexes in muscles engaged in standing balance. These results provide novel evidence that human short-latency GTO-Ib reflexes are dependent upon both task, as evidenced by changes with postural orientation, and context, such as height-induced postural threat during standing. ABSTRACT Golgi tendon organ Ib reflexes are thought to contribute to standing balance control, but it is unknown if they are modulated when people are exposed to a postural threat. We used a novel application of tendon electrical stimulation (TStim) to elicit Ib inhibitory reflexes in the medial gastrocnemius, while actively engaged in upright standing balance, to examine (a) how Ib reflexes to TStim are influenced by upright stance, and (b) the effects of height-induced postural threat on Ib reflexes during standing. TStim evoked short-latency (<47 ms) inhibition apparent in trigger-averaged rectified EMG, which was quantified in terms of area, duration and mean amplitude of inhibition. In order to validate the use of TStim in a standing model, TStim-Ib inhibition was compared from conditions where participants were lying prone vs. standing upright. TStim evoked Ib inhibition in both conditions; however, significant reductions in Ib inhibition area (42.2%) and duration (32.9%) were observed during stance. Postural threat, manipulated by having participants stand at LOW (0.8 m high, 0.6 m from edge) and HIGH (3.2 m, at edge) elevated surfaces, significantly reduced Ib inhibition area (32.4%), duration (16.4%) and amplitude (24.8%) in the HIGH, compared to LOW, threat condition. These results demonstrate TStim is a viable technique for investigating Ib reflexes in standing, and confirm Ib reflexes are modulated with postural orientation. The novel observation of reduced Ib inhibition with elevated postural threat reveals that human Ib reflexes are context dependent, and the human Ib reflex pathways are modulated by threat or emotional processing centres of the CNS.
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Affiliation(s)
- Brian C Horslen
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada.,The Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, Canada
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34
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Spinal and corticospinal pathways are differently modulated when standing at the bottom and the top of a three-step staircase in young and older adults. Eur J Appl Physiol 2017; 117:1165-1174. [PMID: 28409395 DOI: 10.1007/s00421-017-3603-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 03/29/2017] [Indexed: 12/29/2022]
Abstract
PURPOSE This study investigated the modulation of spinal (group Ia afferents) and corticospinal pathways when young (22.7 ± 1.3 years) and older adults (72.2 ± 7.9 years) stood at the bottom and at the top of a three-step staircase equipped with force platforms. METHOD Changes in submaximal H-reflex amplitude (H 50) and slope of the H-reflex input-output relation (spinal pathway), and in amplitude of motor-evoked potentials (MEP) triggered by transcranial magnetic stimulation (corticospinal pathway) at two intensities (1.1× and 1.2× motor threshold) were recorded in soleus when subjects stood as steady as possible downstairs and upstairs. The centre of pressure (CoP) excursion was analyzed in the time and frequency domains in both conditions. RESULTS Regardless of age, the mean CoP velocity was greater when standing upstairs (11.1 ± 3.5 mm s-1) than downstairs (9.0 ± 2.3 mm s-1; p = 0.002). The CoP power spectral density (PSD) in the 0-0.5 Hz band was greater upstairs than downstairs (+18.4%; p = 0.03) whereas PSD in the 2-20Hz frequency band was lesser (-41%) upstairs than downstairs (p < 0.001), regardless of age. In both groups, the H 50 amplitude (-30.6%; p < 0.001) and slope of H-reflex input-output relation (-10.2%; p = 0.002) were lesser when standing upstairs than downstairs, whereas no significant difference was observed in MEP amplitude and silent period between balance conditions (p > 0.05). CONCLUSION These results indicate a lower dependence on spinal pathway to control soleus motor neurones when standing upstairs than downstairs accompanied by a change in postural control. This suggests that healthy older adults preserved their ability to adjust postural control to environmental demands.
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Dubreucq L, Mereu A, Blanc G, Filiatrault J, Duclos C. Introducing a psychological postural threat alters gait and balance parameters among young participants but not among most older participants. Exp Brain Res 2017; 235:1429-1438. [PMID: 28236090 DOI: 10.1007/s00221-017-4902-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 02/02/2017] [Indexed: 11/24/2022]
Abstract
The fear of falling can be manipulated by introducing a postural threat (e.g., an elevated support surface) during stance and gait. Under these conditions, balance parameters are altered in both young and elderly individuals. This study aimed to dissociate the physical and psychological aspects of the threat and show the impact of a verbal warning cue of imminent perturbation during gait among young and elderly healthy participants. Ten young subjects (29.4 ± 3.9 years) and ten subjects aged over 65 years (72.9 ± 3.5) participated in the study. Spatiotemporal and balance parameters were quantified during eight consecutive gait cycles using a motion analysis system and an instrumented treadmill. These parameters were compared twice in the control trial and before/after a verbal warning cue of imminent perturbation during gait ("postural threat") in perturbation trials and between groups using repeated measure ANOVAs. RESULTS The verbal cue yielded reduced step length (p = 0.008), increased step width (p = 0.049), advanced relative position of the center of mass (p = 0.016), increased stabilizing force (p = 0.003), and decreased destabilizing force (p = 0.002). This warning effect was not observed in the older participant group analyses but was found for three participants based on individual data analyses. The warning effect in younger participants was not specific to impending perturbation conditions. Most gait and balance parameters were altered in the older group (p < 0.05) versus the younger group in each condition, regardless of the warning cue. A psychological threat affects gait and balance similarly to a physical threat among young participants but not among most older participants.
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Affiliation(s)
- Lucie Dubreucq
- School of Rehabilitation, Université de Montréal, Montreal, Canada
| | - Aurélie Mereu
- School of Rehabilitation, Université de Montréal, Montreal, Canada
| | - Gabrielle Blanc
- School of Rehabilitation, Université de Montréal, Montreal, Canada
| | | | - Cyril Duclos
- School of Rehabilitation, Université de Montréal, Montreal, Canada.
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36
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Mildren RL, Peters RM, Hill AJ, Blouin JS, Carpenter MG, Inglis JT. Frequency characteristics of human muscle and cortical responses evoked by noisy Achilles tendon vibration. J Appl Physiol (1985) 2017; 122:1134-1144. [PMID: 28209741 DOI: 10.1152/japplphysiol.00908.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/17/2017] [Accepted: 02/11/2017] [Indexed: 11/22/2022] Open
Abstract
Noisy stimuli, along with linear systems analysis, have proven to be effective for mapping functional neural connections. We explored the use of noisy (10-115 Hz) Achilles tendon vibration to examine somatosensory reflexes in the triceps surae muscles in standing healthy young adults (n = 8). We also examined the association between noisy vibration and electrical activity recorded over the sensorimotor cortex using electroencephalography. We applied 2 min of vibration and recorded ongoing muscle activity of the soleus and gastrocnemii using surface electromyography (EMG). Vibration amplitude was varied to characterize reflex scaling and to examine how different stimulus levels affected postural sway. Muscle activity from the soleus and gastrocnemii was significantly correlated with the tendon vibration across a broad frequency range (~10-80 Hz), with a peak located at ~40 Hz. Vibration-EMG coherence positively scaled with stimulus amplitude in all three muscles, with soleus displaying the strongest coupling and steepest scaling. EMG responses lagged the vibration by ~38 ms, a delay that paralleled observed response latencies to tendon taps. Vibration-evoked cortical oscillations were observed at frequencies ~40-70 Hz (peak ~54 Hz) in most subjects, a finding in line with previous reports of sensory-evoked γ-band oscillations. Further examination of the method revealed 1) accurate reflex estimates could be obtained with <60 s of low-level (root mean square = 10 m/s2) vibration; 2) responses did not habituate over 2 min of exposure; and importantly, 3) noisy vibration had a minimal influence on standing balance. Our findings suggest noisy tendon vibration is an effective novel approach to characterize somatosensory reflexes during standing.NEW & NOTEWORTHY We applied noisy (10-115 Hz) vibration to the Achilles tendon to examine the frequency characteristics of lower limb somatosensory reflexes during standing. Ongoing muscle activity was coherent with the noisy vibration (peak coherence ~40 Hz), and coherence positively scaled with increases in stimulus amplitude. Our findings suggest that noisy tendon vibration, along with linear systems analysis, is an effective novel approach to study somatosensory reflex actions in active muscles.
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Affiliation(s)
- Robyn L Mildren
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada;
| | - Ryan M Peters
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Aimee J Hill
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.,Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.,International Collaboration on Repair Discoveries, Vancouver, British Columbia, Canada; and
| | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.,Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada.,International Collaboration on Repair Discoveries, Vancouver, British Columbia, Canada; and
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Cleworth TW, Carpenter MG. Postural threat influences conscious perception of postural sway. Neurosci Lett 2016; 620:127-31. [PMID: 27016388 DOI: 10.1016/j.neulet.2016.03.032] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 03/19/2016] [Accepted: 03/21/2016] [Indexed: 11/29/2022]
Abstract
This study examined how changes in threat influenced conscious perceptions of postural sway. Young healthy adults stood on a forceplate mounted to a hydraulic lift placed at two heights (0.8m and 3.2m). At each height, subjects stood quietly with eyes open and eyes closed for 60s. Subjects were instructed to either stand normal, or stand normal and track their perceived sway in the antero-posterior plane by rotating a hand-held potentiometer. Participants reported an increased level of fear, anxiety, arousal and a decreased level of balance confidence when standing at height. In addition, postural sway amplitude decreased and frequency increased at height. However, there were no effects of height on perceived sway. When standing under conditions of increased postural threat, sway amplitude is reduced, while sway perception appears to remain unchanged. Therefore, when threat is increased, sensory gain may be increased to compensate for postural strategies that reduce sway (i.e. stiffening strategy), thereby ensuring sufficient afferent information is available to maintain, or even increase the conscious perception of postural sway.
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Affiliation(s)
- Taylor W Cleworth
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, BC, Canada; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada.
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38
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Threat-induced changes in attention during tests of static and anticipatory postural control. Gait Posture 2016; 45:19-24. [PMID: 26979877 DOI: 10.1016/j.gaitpost.2015.12.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 12/14/2015] [Accepted: 12/16/2015] [Indexed: 02/02/2023]
Abstract
Postural threat, manipulated through changes in surface height, influences postural control. Evidence suggests changes in attention may contribute to this relationship. However, limited research has explored where and how attention is reallocated when threatened. The primary aim of this study was to describe changes in attention when presented with a postural threat, while a secondary aim was to explore associations between changes in attention and postural control. Eighty-two healthy young adults completed tests of static (quiet standing) and anticipatory (rise to toes) postural control under threatening and non-threatening conditions. Participants completed an open-ended questionnaire after each postural task which asked them to list what they thought about or directed their attention toward. Each item listed was assigned a percentage value reflecting how much attention it occupied. Exit interviews were completed to help confirm where attention was directed. Five attention categories were identified: movement processes, threat-relevant stimuli, self-regulatory strategies, task objectives, and task-irrelevant information. For both postural tasks, the percentage values and number of items listed for movement processes, threat-relevant stimuli, and self-regulatory strategies increased under threatening compared to non-threatening conditions, while the percentage values and number of items listed for task objectives and task-irrelevant information decreased. Changes in attention related to movement processes and self-regulatory strategies were associated with changes in static postural control, while changes in attention related to threat-relevant stimuli were associated with changes in anticipatory postural control. These results suggest that threat-induced changes in attention are multidimensional and contribute to changes in postural control.
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Mildren RL, Zaback M, Adkin AL, Frank JS, Bent LR. Reliability of the Achilles tendon tap reflex evoked during stance using a pendulum hammer. Gait Posture 2016; 43:182-6. [PMID: 26454702 DOI: 10.1016/j.gaitpost.2015.09.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/15/2015] [Accepted: 09/15/2015] [Indexed: 02/02/2023]
Abstract
The tendon tap reflex (T-reflex) is often evoked in relaxed muscles to assess spinal reflex circuitry. Factors contributing to reflex excitability are modulated to accommodate specific postural demands. Thus, there is a need to be able to assess this reflex in a state where spinal reflex circuitry is engaged in maintaining posture. The aim of this study was to determine whether a pendulum hammer could provide controlled stimuli to the Achilles tendon and evoke reliable muscle responses during normal stance. A second aim was to establish appropriate stimulus parameters for experimental use. Fifteen healthy young adults stood on a forceplate while taps were applied to the Achilles tendon under conditions in which postural sway was constrained (by providing centre of pressure feedback) or unconstrained (no feedback) from an invariant release angle (50°). Twelve participants repeated this testing approximately six months later. Within one experimental session, tap force and T-reflex amplitude were found to be reliable regardless of whether postural sway was constrained (tap force ICC=0.982; T-reflex ICC=0.979) or unconstrained (tap force ICC=0.968; T-reflex ICC=0.964). T-reflex amplitude was also reliable between experimental sessions (constrained ICC=0.894; unconstrained ICC=0.890). When a T-reflex recruitment curve was constructed, optimal mid-range responses were observed using a 50° release angle. These results demonstrate that reliable Achilles T-reflexes can be evoked in standing participants without the need to constrain posture. The pendulum hammer provides a simple method to allow researchers and clinicians to gather information about reflex circuitry in a state where it is involved in postural control.
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Affiliation(s)
- Robyn L Mildren
- Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
| | - Martin Zaback
- Department of Kinesiology, Brock University, Saint Catharines, ON, Canada.
| | - Allan L Adkin
- Department of Kinesiology, Brock University, Saint Catharines, ON, Canada.
| | - James S Frank
- Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada.
| | - Leah R Bent
- Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
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40
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Sensory modulation of movement, posture and locomotion. Neurophysiol Clin 2015; 45:255-67. [DOI: 10.1016/j.neucli.2015.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 11/20/2022] Open
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41
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van Dieën JH, van Leeuwen M, Faber GS. Learning to balance on one leg: motor strategy and sensory weighting. J Neurophysiol 2015; 114:2967-82. [PMID: 26400255 DOI: 10.1152/jn.00434.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022] Open
Abstract
We investigated motor and sensory changes underlying learning of a balance task. Fourteen participants practiced balancing on one leg on a board that could freely rotate in the frontal plane. They performed six, 16-s trials standing on one leg on a stable surface (2 trials without manipulation, 2 with vestibular, and 2 with visual stimulation) and six trials on the balance board before and after a 30-min training. Center of mass (COM) movement, segment, and total angular momenta and board angles were determined. Trials on stable surface were compared with trials after training to assess effects of surface conditions. Trials pretraining and posttraining were compared to assess rapid (between trials pretraining) and slower (before and after training) learning, and sensory manipulation trials were compared with unperturbed trials to assess sensory weighting. COM excursions were larger on the unstable surface but decreased with practice, with the largest improvement over the pretraining trials. Changes in angular momentum contributed more to COM acceleration on the balance board, but with practice this decreased. Visual stimulation increased sway similarly in both surface conditions, while vestibular stimulation increased sway less on the balance board. With practice, the effects of visual and vestibular stimulation increased rapidly. Initially, oscillations of the balance board occurred at 3.5 Hz, which decreased with practice. The initial decrease in sway with practice was associated with upweighting of visual information, while later changes were associated with suppression of oscillations that we suggest are due to too high proprioceptive feedback gains.
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Affiliation(s)
- Jaap H van Dieën
- MOVE Research Institute Amsterdam, Department of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Marloes van Leeuwen
- MOVE Research Institute Amsterdam, Department of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands
| | - Gert S Faber
- MOVE Research Institute Amsterdam, Department of Human Movement Sciences, VU University Amsterdam, Amsterdam, The Netherlands
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42
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Personality traits modulate subcortical and cortical vestibular and anxiety responses to sound-evoked otolithic receptor stimulation. J Psychosom Res 2014; 77:391-400. [PMID: 25262497 DOI: 10.1016/j.jpsychores.2014.09.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/31/2014] [Accepted: 09/05/2014] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Strong links between anxiety, space-motion perception, and vestibular symptoms have been recognized for decades. These connections may extend to anxiety-related personality traits. Psychophysical studies showed that high trait anxiety affected postural control and visual scanning strategies under stress. Neuroticism and introversion were identified as risk factors for chronic subjective dizziness (CSD), a common psychosomatic syndrome. This study examined possible relationships between personality traits and activity in brain vestibular networks for the first time using functional magnetic resonance imaging (fMRI). METHODS Twenty-six right-handed healthy individuals underwent fMRI during sound-evoked vestibular stimulation. Regional brain activity and functional connectivity measures were correlated with personality traits of the Five Factor Model (neuroticism, extraversion-introversion, openness, agreeableness, consciousness). RESULTS Neuroticism correlated positively with activity in the pons, vestibulo-cerebellum, and para-striate cortex, and negatively with activity in the supra-marginal gyrus. Neuroticism also correlated positively with connectivity between pons and amygdala, vestibulo-cerebellum and amygdala, inferior frontal gyrus and supra-marginal gyrus, and inferior frontal gyrus and para-striate cortex. Introversion correlated positively with amygdala activity and negatively with connectivity between amygdala and inferior frontal gyrus. CONCLUSIONS Neuroticism and introversion correlated with activity and connectivity in cortical and subcortical vestibular, visual, and anxiety systems during vestibular stimulation. These personality-related changes in brain activity may represent neural correlates of threat sensitivity in posture and gaze control mechanisms in normal individuals. They also may reflect risk factors for anxiety-related morbidity in patients with vestibular disorders, including previously observed associations of neuroticism and introversion with CSD.
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43
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Horslen BC, Dakin CJ, Inglis JT, Blouin JS, Carpenter MG. Modulation of human vestibular reflexes with increased postural threat. J Physiol 2014; 592:3671-85. [PMID: 24973412 DOI: 10.1113/jphysiol.2014.270744] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Anxiety and arousal have been shown to facilitate human vestibulo-ocular reflexes, presumably through direct neural connections between the vestibular nuclei and emotional processing areas of the brain. However, the effects of anxiety, fear and arousal on balance-relevant vestibular reflexes are currently unknown. The purpose of this study was to manipulate standing height to determine whether anxiety and fear can modulate the direct relationship between vestibular signals and balance reflexes during stance. Stochastic vestibular stimulation (SVS; 2-25 Hz) was used to evoke ground reaction forces (GRF) while subjects stood in both LOW and HIGH surface height conditions. Two separate experiments were conducted to investigate the SVS-GRF relationship, in terms of coupling (coherence and cumulant density) and gain, in the medio-lateral (ML) and antero-posterior (AP) directions. The short- and medium-latency cumulant density peaks were both significantly increased in the ML and AP directions when standing in HIGH, compared to LOW, conditions. Likewise, coherence was statistically greater between 4.3 Hz and 6.7 Hz in the ML, and between 5.5 and 17.7 Hz in the AP direction. When standing in the HIGH condition, the gain of the SVS-GRF relationship was increased 81% in the ML direction, and 231% in the AP direction. The significant increases in coupling and gain observed in both experiments demonstrate that vestibular-evoked balance responses are augmented in states of height-induced postural threat. These data support the possibility that fear or anxiety-mediated changes to balance control are affected by altered central processing of vestibular information.
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Affiliation(s)
- Brian C Horslen
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | | | - J Timothy Inglis
- School of Kinesiology, University of British Columbia, Vancouver, Canada International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada Brain Research Centre, University of British Columbia, Vancouver, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, Canada Brain Research Centre, University of British Columbia, Vancouver, Canada The Institute for Computing, Information and Cognitive Systems, University of British Columbia, Vancouver, Canada
| | - Mark G Carpenter
- School of Kinesiology, University of British Columbia, Vancouver, Canada International Collaboration for Repair Discoveries, University of British Columbia, Vancouver, Canada Brain Research Centre, University of British Columbia, Vancouver, Canada
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44
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Needle AR, Baumeister J, Kaminski TW, Higginson JS, Farquhar WB, Swanik CB. Neuromechanical coupling in the regulation of muscle tone and joint stiffness. Scand J Med Sci Sports 2014; 24:737-48. [DOI: 10.1111/sms.12181] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- A. R. Needle
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
| | - J. Baumeister
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
| | - T. W. Kaminski
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
| | - J. S. Higginson
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
| | - W. B. Farquhar
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
| | - C. B. Swanik
- Department of Health and Exercise Science; Appalachian State University; Boone North Carolina USA
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46
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Campbell AD, Squair JW, Chua R, Inglis JT, Carpenter MG. First trial and StartReact effects induced by balance perturbations to upright stance. J Neurophysiol 2013; 110:2236-45. [PMID: 23945786 DOI: 10.1152/jn.00766.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Postural responses (PR) to a balance perturbation differ between the first and subsequent perturbations. One explanation for this first trial effect is that perturbations act as startling stimuli that initiate a generalized startle response (GSR) as well as the PR. Startling stimuli, such as startling acoustic stimuli (SAS), are known to elicit GSRs, as well as a StartReact effect, in which prepared movements are initiated earlier by a startling stimulus. In this study, a StartReact effect paradigm was used to determine if balance perturbations can also act as startle stimuli. Subjects completed two blocks of simple reaction time trials involving wrist extension to a visual imperative stimulus (IS). Each block included 15 CONTROL trials that involved a warning cue and subsequent IS, followed by 10 repeated TEST trials, where either a SAS (TESTSAS) or a toes-up support-surface rotation (TESTPERT) was presented coincident with the IS. StartReact effects were observed during the first trial in both TESTSAS and TESTPERT conditions as evidenced by significantly earlier wrist movement and muscle onsets compared with CONTROL. Likewise, StartReact effects were observed in all repeated TESTSAS and TESTPERT trials. In contrast, GSRs in sternocleidomastoid and PRs were large in the first trial, but significantly attenuated over repeated presentation of the TESTPERT trials. Results suggest that balance perturbations can act as startling stimuli. Thus first trial effects are likely PRs which are superimposed with a GSR that is initially large, but habituates over time with repeated exposure to the startling influence of the balance perturbation.
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Affiliation(s)
- A D Campbell
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and
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Horslen BC, Murnaghan CD, Inglis JT, Chua R, Carpenter MG. Effects of postural threat on spinal stretch reflexes: evidence for increased muscle spindle sensitivity? J Neurophysiol 2013; 110:899-906. [PMID: 23719208 DOI: 10.1152/jn.00065.2013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Standing balance is often threatened in everyday life. These threats typically involve scenarios in which either the likelihood or the consequence of falling is higher than normal. When cats are placed in these scenarios they respond by increasing the sensitivity of muscle spindles imbedded in the leg muscles, presumably to increase balance-relevant afferent information available to the nervous system. At present, it is unknown whether humans also respond to such postural threats by altering muscle spindle sensitivity. Here we present two studies that probed the effects of postural threat on spinal stretch reflexes. In study 1 we manipulated the threat associated with an increased consequence of a fall by having subjects stand at the edge of an elevated surface (3.2 m). In study 2 we manipulated the threat by increasing the likelihood of a fall by occasionally tilting the support surface on which subjects stood. In both scenarios we used Hoffmann (H) and tendon stretch (T) reflexes to probe the spinal stretch reflex circuit of the soleus muscle. We observed increased T-reflex amplitudes and unchanged H-reflex amplitudes in both threat scenarios. These results suggest that the synaptic state of the spinal stretch reflex is unaffected by postural threat and that therefore the muscle spindles activated in the T-reflexes must be more sensitive in the threatening conditions. We propose that this increase in sensitivity may function to satisfy the conflicting needs to restrict movement with threat, while maintaining a certain amount of sensory information related to postural control.
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Affiliation(s)
- Brian C Horslen
- School of Kinesiology, The University of British Columbia, Vancouver, British Columbia, Canada
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Mazaheri M, Coenen P, Parnianpour M, Kiers H, van Dieën JH. Low back pain and postural sway during quiet standing with and without sensory manipulation: a systematic review. Gait Posture 2013; 37:12-22. [PMID: 22796243 DOI: 10.1016/j.gaitpost.2012.06.013] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Revised: 05/08/2012] [Accepted: 06/17/2012] [Indexed: 02/02/2023]
Abstract
A previous review concluded that postural sway is increased in patients with low back pain (LBP). However, more detailed analysis of the literature shows that postural deficit may be dependent on experimental conditions in which patients with LBP have been assessed. The research question to be answered in this review was: "Is there any difference in postural sway between subjects with and without LBP across several sensory manipulation conditions?". A literature search in Pubmed, Scopus, Embase and PsychInfo was performed followed by hand search and contact with authors. Studies investigating postural sway during bipedal stance without applying external forces in patients with specific and non-specific LBP compared to healthy controls were included. Twenty three articles fulfilled the eligibility criteria. Most studies reported an increased postural sway in LBP, or no effect of LBP on postural sway. In a minority of studies, a decreased sway was found in LBP patients. There were no systematic differences between studies finding an effect and those reporting no effect of LBP. The proportion of studies finding between-group differences did not increase with increased complexity of sensory manipulations. Potential factors that may have caused inconsistencies in the literature are discussed in this systematic review.
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Affiliation(s)
- Masood Mazaheri
- Musculoskeletal Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
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