Muscle Tendon Vibration Research Articles

Challenges and opportunities in testing sensorimotor processing with tendon vibration and transcranial magnetic stimulation in subacromial impingement syndrome: A case series.

Non-invasive neurostimulation like muscle tendon vibration (VIB) and transcranial magnetic stimulation (TMS) can provide valuable insights on mechanisms underlying sensorimotor dysfunctions. However, their feasibility in the context of painful musculoskeletal disorders like shoulder impingement syndrome (SIS) remain uncertain. The present work used a case series design including 15 participants with SIS, as well as a secondary group-based analysis comparing participants with SIS to 15 healthy counterparts. Proprioceptive processing was tested by VIB-induced kinesthetic illusions of shoulder abduction, and TMS tested corticospinal excitability of the upper trapezius. Detailed individual data were collected, including any technical challenges and feasibility issues encountered. VIB was in general well-tolerated and elicited a perceptible kinesthetic illusion in 13 participants with SIS and 14 controls. TMS presented with several challenges related to discomfort, fear-related behaviors, technical problems and high motor thresholds, especially in participants with SIS. It was only possible to collect all TMS measures in 5 participants with SIS (for both the painful and non/less-painful sides), in 7 controls on their dominant side and 10 controls on the non-dominant side. The only significant group-based analysis was a lower illusion speed/amplitude on the painful versus non-painful side in persons with SIS (p = 0.035). Our study provides preliminary data on challenges encountered with TMS and VIB of trunk/proximal muscle in persons with SIS and healthy counterparts. It might help future studies to better address those challenges beforehand and improve the overall feasibility and impact of neurostimulation tools in musculoskeletal disorders.

Validity and reliability of proprioception tests with electrogoniometer and mobile application in patients with stroke

BACKGROUND: Although proprioceptive impairment is observed in about half of patients with stroke and is a factor affecting functional recovery and length of hospital stay, there is a discrepancy in terms of its measurement methods between physiotherapy research and the clinical field. This study aimed to examine the concurrent validity and reliability of knee proprioception using an electrogoniometer and a mobile app in patients with stroke. METHODS: In this cross-sectional study, we conducted proprioception tests with an electrogoniometer (custom-made device; Unimec, Japan) and an app (Goniometer Pro; 5fuf5, Bloomfield, NJ) in 28 hospitalized patients with stroke, with an average of 11.21 days (range 2–4 days) from the onset of stroke. Threshold to detect passive motion (TDPM), TDPM+muscle tendon vibration (MTV), and joint position sense (JPS) were used for proprioception tests. These tests were performed three times each in a random order, and the intraclass correlation coefficient, correlation, and absolute reliability for the electrogoniometer and the app were analyzed. RESULTS: Both TDPM and TDPM+MTV measured by the electrogoniometer and the app showed high correlation and “good” to “excellent” reliability regarding the variation in measured values, indicating that the two instruments are compatible, while JPS showed “poor” to “moderate” reliability and weak correlation for the electrogoniometer and the app. CONCLUSIONS: In conclusion, in patients with stroke, TDPM and TDPM+MTV measurements using the Goniometer Pro app can replace measurements with an electrogoniometer.

Dual muscle tendon vibration does not impede performance of a goal-directed aiming task

Aims Application of muscle-tendon vibration within the frequency range of 70–120Hz has been studied as a tool to stimulate somatosensory afferents with both the goal of studying human sensorimotor control and of improving post-stroke motor performance. Specific to applications for rehabilitation, current evidence is mixed as to whether dual muscle-tendon vibration is detrimental to the performance of goal-directed upper-limb movements. The current study aimed to determine the effects of muscle-tendon vibration over the wrist flexors and extensors (dual vibration) on performance of a computer goal-directed aiming task. Methods Twenty healthy participants were assigned to the vibration or control group. An aiming task that involved acquiring targets by moving an unseen cursor on a screen was performed. Vision of the cursor and hand were unavailable throughout the four blocks of movement execution. Only the vibration group received dual vibration throughout four blocks. Task performance was assessed using measures of endpoint accuracy and timing. Perceived hand location was assessed using a set of questions and a computerised conscious perception task. Results The vibration group had significantly shorter reaction times, without any change in endpoint accuracy, indicating more efficient and effective movement planning. The vibration group did report illusory movement sensation, which was reduced by block 4. Conclusions Dual vibration did not adversely affect aiming accuracy and showed some improvement in reaction time. The present findings support the potential for using dual vibration to stimulate the somatosensory system as participants improved their performance of a novel goal-directed movement. Notably, improvements were maintained when the vibration was removed.

Efeitos da vibração do tendão muscular no equilíbrio após acidente vascular cerebral: revisão sistemática

ABSTRACT After cerebrovascular accident (CVA), people have complex combinations of sensory, motor, cognitive, and emotional deficits, which can affect static and dynamic balance. This study aimed to compile and summarize the main features and findings of protocols used in research that investigated the effects of muscle tendon vibration on static and dynamic balance in adults with stroke. This is a systematic review, registered in PROSPERO (CRD42022303874), in which searches were performed in the databases PubMed, Cochrane, LILACS, SciELO, MEDLINE, Science Direct, and PEDro, during the month of January 2022, using the combination of keywords related to “stroke,” “balance,” “muscle tendon vibration,” “randomized controlled trial.” Methodological quality was assessed using the PEDro scale. A total of 1,560 studies were identified, 11 of which were included, between the years 1994 to 2020, involving 242 post-stroke adults. Only five studies used vibration as an intervention and found an improvement in static and dynamic balance. Six studies analyzed the interference of vibration on postural control, showing that balance was affected during the application of vibration and that individuals needed more time to recover or did not experience significant differences. We found that the effects of muscle tendon vibration may be able to improve balance in people with stroke and influence postural control by proprioceptive mechanisms of vibration. However, more studies of high methodological quality are needed to reach a consensus regarding muscle tendon vibration treatment protocols and their recommendation in clinical practice.

Effects of muscle tendon vibration on balance after stroke: systematic review

RESUMO Após o acidente vascular cerebral (AVC), as pessoas apresentam combinações complexas de déficits sensoriais, motores, cognitivos e emocionais que podem afetar o equilíbrio estático e dinâmico. O objetivo do estudo foi compilar e resumir as principais características e achados de protocolos utilizados em pesquisas que investigaram os efeitos da vibração no tendão muscular no equilíbrio estático e dinâmico em adultos com AVC. Trata-se de uma revisão sistemática, registrada na PROSPERO (CRD42022303874), em que foram realizadas buscas nas bases de dados PubMed, Cochrane, LILACS, SciELO, MEDLINE, Science Direct e PEDro, durante o mês de janeiro de 2022, por meio da combinação de palavras-chave relacionadas a “stroke”, “balance”, “muscle tendon vibration” e “randomized controlled trial”. A qualidade metodológica foi avaliada através da escala PEDro. Foram identificados 1.560 estudos, dos quais 11 foram incluídos, publicados entre 1994 e 2020, envolvendo 242 adultos pós-AVC. Apenas cinco estudos utilizaram a vibração como intervenção e verificaram melhora no equilíbrio estático e dinâmico. Seis estudos analisaram a interferência da vibração no controle postural, observando que o equilíbrio foi afetado durante a aplicação da vibração e que os indivíduos precisaram de mais tempo para se recuperar ou não sofreram diferenças significativas. Verificou-se que os efeitos da vibração do tendão muscular podem melhorar o equilíbrio em pessoas com AVC e influenciar o controle postural através de mecanismos proprioceptivos da vibração. Entretanto, são necessários mais estudos de alta qualidade metodológica para atingir um consenso em relação aos protocolos de tratamento com vibração do tendão muscular e sua recomendação na prática clínica.

Abnormal changes in motor cortical maps in humans with spinal cord injury.

The functional role of motor cortical reorganization following spinal cord injury (SCI) remains largely unknown. Here, we tested motor maps in a hand muscle at rest and during voluntary contraction of the hand with and without voluntary contraction of a proximal arm muscle. Motor map area in participants with SCI decreased during hand voluntary contraction and further decreased during additional contraction of a proximal arm muscle compared with rest. In contrast, motor map area in controls increased during the same motor tasks. Participants with SCI with more severe sensory deficits in the hand showed larger decreases in motor map area. Ten minutes of hand muscle-tendon vibration increased the motor map area during voluntary contraction in SCI participants. These novel findings suggest that abnormal changes in motor cortical maps during voluntary contraction after SCI can be reshaped by sensory input, knowledge that can have implications for rehabilitation. Motor cortical representations reorganize following cervical spinal cord injury (SCI). The functional role of this reorganization remains largely unknown. Using neuronavigated transcranial magnetic stimulation, we examined motor cortical maps during voluntary contraction in humans with chronic cervical SCI and age-matched controls. We constructed motor maps in the first dorsal interosseous (FDI) muscle at rest and during voluntary contraction of the FDI with and without voluntary contraction of the biceps brachi (BB). The role of sensory input into this reorganization was examined by muscle-tendon vibration. We found that, at rest, motor maps were larger in SCI (22.3cm2 ) compared with control (12.6cm2 , P<0.001) participants. Motor map area increased during voluntary contraction of the FDI (120.7%) and further increased during contraction of the BB (143.9%) compared with rest in control subjects; however, motor map area decreased during voluntary contraction of the FDI (69.5%) and further decreased during contraction of the BB (55.5%) in individuals with SCI. SCI participants with larger decreases in map area during voluntary contraction of the FDI were those with larger sensory deficits in the hand and 10min of hand muscle-tendon vibration increased motor map area. These results provide the first evidence of abnormal changes in motor cortical maps in humans with chronic SCI during voluntary contraction, suggesting that sensory input can help to reshape this reorganization.

The acute effects of periodic and noisy tendon vibration on wrist muscle stretch responses

Mechanical muscle tendon vibration activates multiple sensory receptors in the muscle and tendon. In particular, tendon vibration tends to activate the Ia afferents the strongest, but also will activate group II and Ib afferents. This activation can cause three main effects in the central nervous system: proprioceptive illusions, tonic vibration reflexes, and suppression of the stretch response. Noisy tendon vibration has been used to assess the frequency characteristics of proprioceptive reflexes and, interestingly there appeared to be no evidence for proprioceptive illusions or tonic vibration reflexes during standing [9]. However, it remains unknown if noisy vibration induces a suppression of the muscle stretch response. Therefore, the purpose of this study was to investigate the effects of noisy and periodic tendon vibration on the stretch response in the flexor carpi radialis muscle (FCR). We examined FCR stretch responses with and without periodic (20 and 100 Hz) and noisy (∼10–100 Hz) tendon vibration. We additionally had participants perform the task under the instruction set to either not respond to the perturbation or to respond as fast as possible. The key finding from this study was that both periodic and noisy vibration resulted in a reduced stretch response amplitude. Additionally, it was found that a participant’s intent to respond did not modulate the amount of suppression observed. The findings from this study provide a more detailed understanding of the effects of tendon vibration on the muscle stretch response.

Interaction Effects Between BDNF Gene rs6265 Polymorphism and Parental Harsh Discipline on Preschoolers’ Working Memory Performance

In the present study, muscle pain was induced experimentally in healthy subjects by administrating hypertonic saline injections into the tibialis anterior (TA) muscle. We first aimed at comparing the analgesic effects of mechanical vibration applied to either cutaneous or muscle receptors of the TA or to both types simultaneously. Secondly, pain alleviation was compared in subjects in whom muscle tendon vibration evoked kinesthetic illusions of the ankle joint. Muscle tendon vibration, which primarily activated muscle receptors, reduced pain intensity by 30% (p<0.01). In addition, tangential skin vibration reduced pain intensity by 33% (p<0.01), primarily by activating cutaneous receptors. Concurrently stimulating both sensory channels induced stronger analgesic effects (−51%, p<0.01), as shown by the lower levels of electrodermal activity. The strongest analgesic effects of the vibration-induced muscle inputs occurred when illusory movements were perceived (−38%, p=0.01). The results suggest that both cutaneous and muscle sensory feedback reduce muscle pain, most likely via segmental and supraspinal processes. Further clinical trials are needed to investigate these new methods of muscle pain relief.

Contributions of exercise-induced fatigue versus intertrial tendon vibration on visual-proprioceptive weighting for goal-directed movement.

It has been argued that exercise-induced muscle fatigue and tendon vibration can alter proprioceptive estimates of limb position. While exercise-induced muscle fatigue may also affect central efferent processes related to limb position sense, tendon vibration specifically targets peripheral afferent signals. It is unclear, however, whether either of these perturbations (i.e., muscle fatigue or tendon vibration) can alter the multisensory weighting processes preceding goal-directed movements. The current study sought to specifically explore visual-proprioceptive weighting before or after eccentric exercise-induced antagonist muscle fatigue (experiment 1) versus with or without intertrial simultaneous agonist-antagonist tendon vibration (experiment 2). To assess sensory weighting, a visual-proprioceptive mismatch between the participant's actual initial starting position and the associated visual cursor position was employed. This method provides an estimate of the participant's reliance on the proprioceptive or visual starting limb position for their aiming movements. Although there was clear evidence of muscle fatigue, there was no systematic alteration of proprioceptive weighting after eccentric exercise and no relationship between sensory weighting and the level of fatigue. On the other hand, participants' reliance on their actual (proprioceptive) limb position was systematically reduced when exposed to agonist-antagonist tendon vibration before each aiming movement. These findings provide seminal evidence that intertrial tendon vibration, but not exercise-induced fatigue, can alter the reliability of proprioceptive estimates and the relative contributions of visual and proprioceptive information for goal-directed movement.NEW & NOTEWORTHY Previous work has used muscle fatigue or tendon vibration to perturb proprioceptive limb position estimates. This study sought to determine whether exercise-induced muscle fatigue versus intertrial tendon vibration can alter multisensory weighting for upper limb-aiming movements. By introducing a discrepancy between participants' actual proprioceptive and visual finger position, this study provides seminal evidence for the reduction of proprioceptive-to-visual weighting using intertrial tendon vibration but no evidence for a systematic reduction following exercise-induced fatigue.

Subthalamic Deep Brain Stimulation Modulates Proprioceptive Integration in Parkinson’s Disease During a Postural Task

Defective proprioceptive integration may play a role in the pathophysiology of motor symptoms in Parkinson’s disease (PD). Dysfunction related to proprioceptively-evoked postural reactions in PD patients is still a controversial issue, with only a limited number of studies to date and mostly discordant results. The aims of the present study were (1) to determine whether or not the proprioceptive defect in PD underlies postural impairment and (2) whether or not deep brain stimulation of the subthalamic nucleus (STN-DBS) affects proprioceptive integration.We examined proprioceptive integration during a postural task in 13 PD patients and 12 age-matched control subjects, using a muscle–tendon vibration paradigm.Analysis of the center of pressure displacement and kinematic data indicates a greater degree of postural destabilization and a reduced ability to maintain a vertical orientation in PD. We found a significant positive effect of STN-DBS on these postural features.Our findings indicate that Parkinson patients, even in the absence of any clinical evidence of instability, falls, or freezing, use proprioceptive information for postural control less efficiently than healthy subjects. Furthermore, STN-DBS was found to improve proprioceptive integration, with positive impacts on postural orientation and balance.

Effect of Mechanical Stimulation Applied to the Lower-Limb Musculature on Stability and Function of Stair Climbing

Mechanical muscle-tendon vibration affects musculature and the nervous system. As the vibrations used in previous studies were varied, consistently determining the effect of mechanical vibration was challenging. Additionally, only a few studies have applied vibrations to dynamic motion. This study investigated whether the vibration based on the sensorimotor response could affect the stability and function of stair climbing. Electroencephalogram (EEG) signals were recorded from the sensorimotor area, and mu rhythms, dependent on the vibration frequencies, were analyzed. Based on the analysis, the vibratory stimulus conditions were set and applied to the Achilles tendon of the lower limb during stair climbing. Simultaneously, electromyogram (EMG) signals from the gastrocnemius lateralis (GL), gastrocnemius medialis (GM), soleus (SOL), and tibialis anterior (TA) were recorded. Activations and co-activations of the shank muscles were analyzed according to the phases of stair climbing. When vibration was applied, the TA activation decreased in the pull-up (PU) phase, and calf muscle activations increased during the forward continuous (FCN) phase. These changes and their degrees differ significantly between stimulus conditions (p &lt; 0.05). Co-activation changes, which differed significantly with conditions (p &lt; 0.05), appeared mostly in the PU. These results imply that the vibration affects stability and function of stair climbing, suggesting that the vibration characteristics should be considered when they are applied to dynamic movement.

A new method to elicit and measure movement illusions in stroke by means of muscle tendon vibration: the Standardized Kinesthetic Illusion Procedure (SKIP)

Purpose: Muscle tendon vibration (MTV) strongly activates muscle spindles and can evoke kinaesthetic illusions. Although potentially relevant for sensorimotor rehabilitation in stroke, MTV is scarcely used in clinical practice, likely because of the absence of standardised procedures to elicit and characterise movement illusions. This work developed and validated a Standardised Kinaesthetic Illusion Procedure (SKIP) to favour the use of MTV-induced illusions in clinical settings.Materials and methods: SKIP scores were obtained in 15 individuals with chronic stroke and 18 age- and gender-matched healthy counterparts. A further 13 healthy subjects were tested to provide more data with the general population. MTV was applied over the Achilles tendon and SKIP scoring system characterised the clearness and direction of the illusions of ankle dorsiflexion movements.Results: All healthy and stroke participants perceived movement illusions. SKIP scores on the paretic side were significantly lower compared to the non paretic and healthy. Illusions were less clear and sometimes in unexpected directions with the impaired ankle, but still possible to elicit in the presence of sensorimotor deficits.Conclusions: SKIP represents an ancillary and potentially useful clinical method to elicit and characterise illusions of movements induced by MTV. SKIP could be relevant to further assess the processing of proprioceptive afferents in stroke and their potential impact on motor control and recovery. It may be used to guide therapy and improve sensorimotor recovery. Future work is needed to investigate the metrological properties of our method (reliability, responsiveness, etc.), and also the neurophysiological underpinnings of MTV-induced illusions.

Kinaesthetic illusion shapes the cortical plasticity evoked by action observation.

The combination of action observation (AO) and a peripheral nerve stimulation has been shown to induce plasticity in the primary motor cortex (M1). However, using peripheral nerve stimulation little is known about the specificity of the sensory inputs. The current study, using muscle tendon vibration to stimulate muscle spindles and transcranial magnetic stimulation to assess M1 excitability, investigated whether a proprioceptive stimulation leading to a kinaesthetic illusion of movement (KI) was able to evoke M1 plasticity when combined with AO. M1 excitability increased immediately and up to 60min after AO-KI stimulation as a function of the vividness of the perceived illusion, and only when the movement directions of AO and KI were congruent. Tactile stimulation coupled with AO and KI alone were not sufficient to induce M1 plasticity. This methodology might be proposed to subjects during a period of immobilization to promote M1 activity without requiring any voluntary movement. Physical practice is crucial to evoke cortical plasticity, but motor cognition techniques, such as action observation (AO), have shown their potentiality in promoting it when associated with peripheral afferent inputs, without the need of performing a movement. Here we investigated whether the combination of AO and a proprioceptive stimulation, able to evoke a kinaesthetic illusion of movement (KI), induced plasticity in the primary motor cortex (M1). In the main experiment, the role of congruency between the observed action and the illusory movement was explored together with the importance of the specificity of the sensory input modality (proprioceptive vs. tactile stimulation) to induce plasticity in M1. Further, a control experiment was carried out to assess the role of the mere kinaesthetic illusion on M1 excitability. Results showed that the combination of AO and KI evoked plasticity in M1, with an increase of the excitability immediately and up to 60min after the conditioning protocol (P always <0.05). Notably, a significant increase in M1 excitability occurred only when the directions of the observed and illusory movements were congruent. Further, a significant positive linear relationship was found between the amount of M1 excitability increase and the vividness of the perceived illusion (P=0.03). Finally, the tactile stimulation coupled with AO was not sufficient to induce changes in M1 excitability as well as the KI alone. All these findings indicate the importance of combining different sensory input signals to induce plasticity in M1, and that proprioception is the most suitable sensory modality to allow it.

On the reflex mechanisms of cervical transcutaneous spinal cord stimulation in human subjects.

Transcutaneous and epidural electrical spinal cord stimulation techniques are becoming more valuable as electrophysiological and clinical tools. Recently, remarkable recovery of the upper limb sensorimotor function during cervical spinal stimulation was demonstrated. In the present study, we sought to elucidate the neural mechanisms underlying the effects of transcutaneous spinal cord stimulation (tSCS) of the cervical spine. We hypothesized that cervical tSCS can be used to selectively activate the sensory route entering the spinal cord and transsynaptically converge on upper limb motor pools. To test this hypothesis, we applied cervical tSCS using paired stimuli (homosynaptic depression) and during passive muscle stretching of the wrist flexor (presynaptic inhibition via Ia afferents), voluntary hand muscle contraction (descending facilitation of motoneuron pool), and muscle-tendon vibration of the wrist (presynaptic inhibition via afferent occlusion). Our results demonstrate significant inhibition of the second evoked response during paired stimulus delivery, inhibition of responses during passive muscle stretching and muscle-tendon vibration, and facilitation during voluntary muscle contraction, which share similarities with responses evoked during lumbosacral tSCS. These results indicate that the route of the stimulation current transmission passes via afferents in the dorsal roots through the spinal cord to activate the motor pools and potentially interneuronal networks projecting to upper limb muscles. Using a novel stimulation paradigm, our study is the first to present evidence of the sensory neuronal pathway of the cervical tSCS propagation. Overall, our work demonstrates the utility and sensitivity of cervical tSCS to engage the sensory pathway projecting to the upper limbs. NEW & NOTEWORTHY Despite therapeutic effects that have been demonstrated previously using noninvasive cervical spinal stimulation, it has been unclear whether, and to what degree, the stimulation can activate the sensory afferent system. Our study presents evidence that cervical transcutaneous spinal cord stimulation can engage the sensory pathways and transsynaptically converge on motor pools projecting to upper limb muscles, demonstrating the utility and sensitivity of cervical spinal stimulation for electrophysiological assessments and neurorehabilitation.

Intermediate Muscle Length and Tendon Vibration Optimize Corticospinal Excitability During Knee Extensors Local Vibration.

While local vibration (LV) has been recently proposed as a potential modality for neuromuscular conditioning, no practical recommendations to optimize its effects have been published. Because changes in corticospinal excitability may reflect at which degree the neuromuscular function is modulated during LV exposure, this study investigated the effects of muscle length and vibration site on LV-induced on motor evoked potentials (MEPs) changes. Twenty-one subjects participated in a single session in which MEPs were evoked on the relaxed knee extensors (KE) during three conditions, i.e., no vibration (CON), muscle (VIBMU), and tendon vibration (VIBTD). Three muscle lengths were tested for each condition, i.e., short/intermediate/long KE muscle length. Both VIBMU and VIBTD significantly increase MEPs compared to CON. Higher increases (P < 0.001) were found for VIBTD compared to VIBMU for vastus lateralis (mean increases of the three angles: +241% vs.+ 148%), vastus medialis (+273% vs. + 180%) and rectus femoris muscles (+191% vs. +141%). The increase in MEPs amplitude was higher (p < 0.001) at an intermediate (mean pooled increase for VIBTD and VIBMU: +265%, +290%, and +212% for VL, VM, and RF, respectively) compared to short (+136%, + 144%, and + 127%) or long (+ 184%, + 246% and + 160%) muscle lengths. These results suggest that LV should be applied to the tendon at an intermediate muscle length to optimize the acute effects of LV on the KE neuromuscular function.

Effects of wrist tendon vibration and eye movements on manual aiming.

In the present study, we investigated whether visual information mediates a proprioceptive illusion effect induced by muscle tendon vibration in manual aiming. Visual information was gradually degraded from a situation in which the targets were present and participants (n = 20; 22.3 ± 2.7years) were permitted to make saccadic eye movements to designated target positions, to a condition in which the targets were not visible and participants were required to perform cyclical aiming while fixating a point between the two target positions. Local tendon vibration applied to the right wrist extensor muscles induced an illusory reduction of 15% in hand movement amplitude. This effect was greater in the fixation than in the saccade condition. Both anticipatory control and proprioceptive feedback are proposed to contribute to the observed effects. The primary saccade amplitude was also reduced by almost 4% when muscle tendon vibration was locally applied to the wrist. These results confirm a tight link between eye movements and manual perception and action. Moreover, the impact of the proprioceptive illusion on the ocular system indicates that the interaction between systems is bidirectional.

Illusory limb movements activate different brain networks than imposed limb movements: an ALE meta-analysis

Proprioceptive information allows us to perform smooth coordinated movements by constantly updating us with knowledge of the position of our limbs in space. How this information is combined and processed to form conscious perceptions of limb position is still relatively unknown. Several functional neuroimaging studies have attempted to tease out the brain areas responsible for proprioceptive processing in the human brain. Yet there still exists some disagreement in the specific brain regions involved. In order to consolidate the current knowledge in the field, we performed a systematic review of the literature and an activation likelihood estimation (ALE) meta-analysis of functional neuroimaging studies of proprioception. We identified 12 studies that used a proprioceptive stimulus of the upper extremity for ALE analysis (n=141 participants). Two types of stimuli (illusion of movement induced through muscle tendon vibration and passive/imposed movements) were found to be most commonly used to probe proprioceptive networks in the brain. ALE analysis of these two stimulus types revealed that both were associated with activation in the left precentral, postcentral, and anterior cingulate gyri. Interestingly, different patterns of activation were also observed between illusions of movement and imposed movement. In the left hemisphere, imposed movements resulted in activations that were more inferior in the post-central gyrus. In the right hemisphere, imposed movements resulted in two clusters of activation in the inferior aspect of the precentral gyrus and the hand area of the post-central gyrus, while illusions of movement resulted in a single cluster of activation in the inferior parietal lobule. These results suggest that illusions of movement without limb displacement may activate different brain areas compared with actual limb displacement. Careful consideration should be made in future studies when selecting a proprioceptive stimulus to probe these brain networks.

After-effects of peripheral neurostimulation on brain plasticity and ankle function in chronic stroke: The role of afferents recruited

This study tested the after-effects of neuromuscular electrical stimulation (NMES), repetitive peripheral magnetic stimulation (rPMS) and muscle tendon vibration (VIB) on brain plasticity and sensorimotor impairments in chronic stroke to investigate whether different results could depend on the nature of afferents recruited by each technique. Fifteen people with chronic stroke participated in five sessions (one per week). Baseline measures were collected in session one, then, each participant received 4 randomly ordered interventions (NMES, rPMS, VIB and a 'control' intervention of exercises). Interventions were applied to the paretic ankle muscles and parameters of application were matched as closely as possible. Standardized clinical measures of the ankle function on the paretic side and transcranial magnetic stimulation (TMS) outcomes of both primary motor cortices (M1) were collected at pre- and post-application of each intervention. The ankle muscle strength was significantly improved by rPMS and VIB (P≤0.02). rPMS influenced M1 excitability (increase in the contralesional hemisphere, P=0.03) and inhibition (decrease in both hemispheres, P≤0.04). The group mean of a few clinical outcomes improved across sessions, i.e. independently of the order of interventions. Some TMS outcomes at baseline could predict the responsiveness to rPMS and VIB. This original study suggests that rPMS and VIB were efficient to drive M1 plasticity and sensorimotor improvements, likely via massive inflows of 'pure' proprioceptive information generated. Usefulness of some TMS outcomes to predict which intervention a patient could be more responsive to should be further tested in future studies.

Changes in proprioceptive weighting during quiet standing in women with early and established knee osteoarthritis compared to healthy controls

ObjectivesKnee osteoarthritis (OA) is highly prevalent in people above the age of 60, and is typically associated with pain, stiffness, muscle weakness and proprioceptive deficits. Muscle-tendon vibration has been used to assess the spatial reweighting of proprioceptive input during standing. The current study aimed to investigate whether weighting of proprioceptive input is altered in patients with early and established knee OA compared to asymptomatic controls. MethodsThe upright posture of 27 participants with early OA, 26 with established OA, and 27 asymptomatic controls was perturbed by vibrating (frequency: 70Hz and amplitude: approximately 0.5mm) ankle muscles (i.e. tibialis anterior and triceps surae) and knee muscles (vastus medialis). Center of pressure displacements of the participants were recorded using a force plate. ResultsBoth patients with early and established OA were more sensitive to triceps surae vibration compared to their healthy peers (P<0.01 for both). No such difference was found for the vibration of tibialis anterior or vastus medialis muscles between patients with knee OA and healthy controls. ConclusionsThese results suggest that the early stages of knee OA may already lead to reweighting of proprioceptive information, suggesting more reliance on ankle proprioceptive input for postural control.

Can explicit visual feedback of postural sway efface the effects of sensory manipulations on mediolateral balance performance?

Explicit visual feedback on postural sway is often used in balance assessment and training. However, up-weighting of visual information may mask impairments of other sensory systems. We therefore aimed to determine whether the effects of somatosensory, vestibular, and proprioceptive manipulations on mediolateral balance are reduced by explicit visual feedback on mediolateral sway of the body center of mass and by the presence of visual information. We manipulated sensory inputs of the somatosensory system by transcutaneous electric nerve stimulation on the feet soles (TENS) of the vestibular system by galvanic vestibular stimulation (GVS) and of the proprioceptive system by muscle-tendon vibration (VMS) of hip abductors. The effects of these manipulations on mediolateral sway were compared with a control condition without manipulation under three visual conditions: explicit feedback of sway of the body center of mass (FB), eyes open (EO), and eyes closed (EC). Mediolateral sway was quantified as the sum of energies in the power spectrum and as the energy at the dominant frequencies in each of the manipulation signals. Repeated-measures ANOVAs were used to test effects of each of the sensory manipulations, of visual conditions and their interaction. Overall, sensory manipulations increased body sway compared with the control conditions. Absence of normal visual information had no effect on sway, while explicit feedback reduced sway. Furthermore, interactions of visual information and sensory manipulation were found at specific dominant frequencies for GVS and VMS, with explicit feedback reducing the effects of the manipulations but not effacing these.