Effects of 24-week Tai Chi exercise on the knee and ankle proprioception of older women

This study examined the effects of regular Tai Chi (TC) exercise on the kinaesthesia of the knee and ankle joints of older women. A total of 43 women aged 55–68 years participated in this study. In a 24-week study period, the TC group (n = 22) underwent an organized TC exercise, whereas the control group (n = 21) maintained a sedentary lifestyle. Customized instruments were used to measure the threshold for the detection of the passive motion of the knee and ankle joints. After 24 weeks, the TC group showed a significantly smaller threshold for the detection of passive motion of knee extension (31.4%, p = 0.009), knee flexion (27.0%, p = 0.044), and ankle dorsal flexion (28.9%, p = 0.014) than the control group. Other comparisons showed no significant differences. The 24-week TC exercise benefited the lower-limb kinaesthesia of the knee joint flexion and extension and ankle dorsal flexion.     

移动式平板训练对脑卒中偏瘫患者的运动功能及日常生活活动能力的影响

目的：观察移动式平板训练对脑卒中偏瘫患者本体感觉障碍的运动能力及日常生活活动能力的影响。方法：脑卒中偏瘫患者30例随机分为观察组和对照组各15例,2组患者均给予常规药物治疗及康复训练,观察组加用移动式平板训练进行本体感觉训练,对照组加用神经肌肉本体感觉促进疗法（PNF）进行治疗。治疗前后采用Tecnobody本体感觉评估系统（ATE及Time值）、Fugl-Meyer下肢运动功能评定量表（FMA）、Berg平衡量表（BBS）、改良Barthel指数评定表（MBI）评估2组患者的本体感觉、下肢运动功能、平衡能力及日常生活活动能力。 结果：治疗8周后,2组ATE值及Time值均较治疗前明显降低（P<0.05）,且观察组更低于对照组（P<0.05）;2组FMA、BBS、MBI评分均较治疗前明显提高（P<0.05）,且观察组FMA评分较对照组明显提高（P<0.05）,但BBS、MBI评分2组间比较差异无统计学意义。结论：移动式平板训练对脑卒中偏瘫患者本体感觉及下肢运动功能的疗效优于PNF疗法;对于平衡能力及日常生活活动能力的改善,两者未见明显区别。     

Long-term plasticity in adult somatosensory cortex: functional reorganization after surgical removal of an arteriovenous malformation

The temporal scale of neuroplasticity following acute alterations in brain structure due to neurosurgical intervention is still under debate. We conducted a longitudinal study with the objective of investigating the postoperative changes in a patient who underwent cerebrovascular surgery and who subsequently lost proprioception in the fingers of her right hand. The results show increased activation in contralesional somatosensory areas, additional recruitment of premotor and posterior parietal areas, and changes in functional connectivity with left postcentral gyrus. These findings demonstrate long-term modifications of cortical organization and as such have important implications for treatment strategies for patients with brain injury.     

Task‐dependent responses to muscle vibration during reaching

Feedback corrections in reaching have been shown to be task‐dependent for proprioceptive, visual and vestibular perturbations, in line with predictions from optimal feedback control theory. Mechanical perturbations have been used to elicit proprioceptive errors, but have the drawback to actively alter the limb's trajectory, making it nontrivial to dissociate the subject's compensatory response from the perturbation itself. In contrast, muscle vibration provides an alternative tool to perturb the muscle afferents without changing the hands trajectory, inducing only changes in the estimated, but not the actual, limb position and velocity. Here, we investigate whether upper‐arm muscle vibration is sufficient to evoke task‐dependent feedback corrections during goal‐directed reaching to a narrow versus a wide target. Our main result is that for vibration of biceps and triceps, compensatory responses were down‐regulated for the wide compared to the narrow target. The earliest detectable difference between these target‐specific corrections is at about 100 ms, likely reflecting a task‐dependent feedback control policy rather than a voluntary response.     

Neural correlates of lower limbs proprioception: An fMRI study of foot position matching

Little is known about the neural correlates of lower limbs position sense, despite the impact that proprioceptive deficits have on everyday life activities, such as posture and gait control. We used fMRI to investigate in 30 healthy right‐handed and right‐footed subjects the regional distribution of brain activity during position matching tasks performed with the right dominant and the left nondominant foot. Along with the brain activation, we assessed the performance during both ipsilateral and contralateral matching tasks. Subjects had lower errors when matching was performed by the left nondominant foot. The fMRI analysis suggested that the significant regions responsible for position sense are in the right parietal and frontal cortex, providing a first characterization of the neural correlates of foot position matching.     

Effect of interstimulus interval on cortical proprioceptive responses to passive finger movements

Shortening of the interstimulus interval (ISI) generally leads to attenuation of cortical sensory responses. For proprioception, however, this ISI effect is still poorly known. Our aim was to characterize the ISI dependence of movement‐evoked proprioceptive cortical responses and to find the optimum ISI for proprioceptive stimulation. We measured, from 15 healthy adults, magnetoencephalographic responses to passive flexion and extension movements of the right index finger. The movements were generated by a movement actuator at fixed ISIs of 0.5, 1, 2, 4, 8, and 16 s, in separate blocks. The responses peaked at ~ 70 ms (extension) and ~ 90 ms (flexion) in the contralateral primary somatosensory cortex. The strength of the cortical source increased with the ISI, plateauing at the 8‐s ISI. Modeling the ISI dependence with an exponential saturation function revealed response lifetimes of 1.3 s (extension) and 2.2 s (flexion), implying that the maximum signal‐to‐noise ratio (SNR) in a given measurement time is achieved with ISIs of 1.7 s and 2.8 s respectively. We conclude that ISIs of 1.5–3 s should be used to maximize SNR in recordings of proprioceptive cortical responses to passive finger movements. Our findings can benefit the assessment of proprioceptive afference in both clinical and research settings.     

Effects of the availability of accurate proprioceptive information on older adults' postural sway and muscle co‐contraction

During conditions of increased postural instability, older adults exhibit greater lower limb muscle co‐contraction. This response has been interpreted as a compensatory postural strategy, which may be used to increase proprioceptive information from muscle spindles or to stiffen the lower limb as a general response to minimise postural sway. The current study aimed to test these two hypotheses by investigating use of muscle co‐contraction during sensory transitions that manipulated proprioceptive input. Surface EMG was recorded from the bilateral tibialis anterior and gastrocnemius medialis muscles, in young (aged 18–30) and older adults (aged 68–80) during blind‐folded postural assessment. This commenced on a fixed platform (baseline: 2 min), followed by 3 min on a sway‐referenced platform (adaptation) and a final 3 min on a fixed platform again (reintegration). Sensory reweighting was slower in older adults, as shown by a significantly larger and longer postural sway after‐effect once a stable platform was restored. Muscle co‐contraction showed similar after‐effects, whereby older adults showed a larger increase in co‐contraction once the stable platform had been restored, compared to young adults. This co‐contraction after‐effect did not return to baseline until after 1 min. Our evidence for high muscle co‐contraction during the reintroduction of veridical proprioceptive input suggests that increased co‐contraction in older adults is not dependent on contemporaneous proprioceptive input. Rather, it is more likely that co‐contraction is a general postural strategy used to minimise postural sway, which is increased during this sensory transition. Future research should examine whether muscle co‐contraction is typically a reactive or anticipatory response.     

Mechanoreceptors of the ligaments and tendons around the knee

Proprioceptive inputs from the joints and limbs arise from mechanoreceptors in the muscles, ligaments and tendons. The knee joint has a wide range of movements, and proper neuroanatomical organization is critical for knee stability. Four ligaments (the anterior (ACL) and posterior (PCL) cruciate ligaments and the medial (MCL) and lateral (LCL) collateral ligaments) and four tendons (the semitendinosus (STT), gracilis (GT), popliteal (PoT), and patellar (PaT) tendons) from eight fresh frozen cadavers were harvested. Each harvested tissue was divided into its bone insertion side and its tendinous part for immunohistochemical examination using S100 staining. Freeman–Wyke's classification was used to identify the mechanoreceptors. The mechanoreceptors were usually located close to the bone insertion. Free nerve endings followed by Ruffini endings were the most common mechanoreceptors overall. No Pacini corpuscles were observed; free nerve endings and Golgi‐like endings were most frequent in the PCL (PCL‐PaT: P = 0.0.1, PCL‐STT: P = 0.00), and Ruffini endings in the popliteal tendon (PoT‐PaT: P = 0.00, Pot‐STT: P = 0.00, PoT‐LCL: P = 0.00, PoT‐GT: P = 0.00, PoT‐ACL: P = 0.09). The cruciate ligaments had more mechanoreceptors than the medial structures (MS) or the patellar tendon (CR‐Pat: P = 0.000, CR‐MS: P = 0.01). The differences in mechanoreceptor distributions between the ligaments and tendons could reflect the different roles of these structures in the dynamic coordination of knee motion. Clin. Anat. 29:789–795, 2016. © 2016 Wiley Periodicals, Inc.     

Effect of elastic bandage on postural control in subjects with chronic ankle instability: a randomised clinical trial

Purpose: To report the immediate and prolonged (one week) effects of elastic bandage (EB) on balance control in subjects with chronic ankle instability.

Material and methods: Twenty-eight individuals successfully completed the study protocol, of whom 14 were randomly assigned to the EB group (7 men, 7 women) and 14 were assigned to the non-standardised tape (NST) group (9 men, 5 women). To objectively measure postural sway we used computerised dynamic posturography (CDP) with sensory organisation test (SOT) and unilateral stance (US) test. We analysed the following SOT parameters: the composite SOT score, the composite SOT strategy and the SOT condition 2 and its strategy. In addition, we studied the centre of gravity (COG) sway velocity with open eyes and close eyes during the US test.

Results: Repeated measures ANOVA showed a significant effect for time in composite SOT score (F=?34.98; p=?<0.01), composite SOT strategy (F=?12.082; p=?0.02), and COG sway with open eyes (F=?3.382; p=?0.039) in EB group and NST group. Therefore, there were improvements in balance control after bandage applications (defined as better scores in SOT parameters and decreased COG sway in US test). However, no differences between groups were observed in the most relevant parameters.

Conclusions: This study did not observe differences between EB and NST during the follow-up in the majority of measurements. Several outcome measures for SOT and US tests improved in both groups immediately after bandage applications and after one week of use. EB of the ankle joint has no advantage as compared to the non-standardised tape.

• Implications for rehabilitation

• Elastic bandage (EB) of the ankle joint has no advantage as compared to the non-standardised tape.

• The effects of the bandages could be due to a greater subjective sense of security.

• It is important to be prudent with the use of bandage, since a greater sense of safety could also bring with it a greater risk of injury.

• The application of the bandage on subjects with chronic ankle instability (CAI) should be prolonged and used alongside other physiotherapy treatments.