The Effects of Sensory Perceptual Isolation on Single Motor Unit Conditioning

Forty male volunteers were injected with bipolar fine-wire electrodes into the tibialis anterior muscle and trained to isolate and cunt nil a single motor unit. A light panel indicated trial onsets and correct and incorrect responses. Subjects were randomly assigned to the isolation or non-isolation condition for both sessions. Isolation condition was produced In an air-fluidized. ceramic-bead bed in a light attenuating chamber. A relearning session followed the initial session after a two week interim rest. The hypodynamic effects of sensory isolation increased the speed of learning to isolate and control an SMU. The results. suggested that subjects were better able to attend to the relatively weak proprioceptive information provided by the SMU through the reduction of the amount and/or variety of competing stimuli.     

A Comparison of Auditory and Visual Feedback in Biofeedback Assisted Muscular Relaxation Training

This study compared the efficacy of auditory and visual feedback in electromyographic (EMG) biofeedback assisted relaxation training of the frontalis muscle.Twenty-eight subjects, divided into 4 groups matched on baseline frontalis EMG levels and trait anxiety, received 7 training sessions each under one of the following conditions: (1) auditory feedback-eyes closed; (2) auditory feedback-eyes open; (3) visual feedback; or (4) no feedback-eyes closed. The group who received auditory feedback with the eyes closed manifested significant lowering of EMG over session compared to no significant reduction in EMG for the other three groups. EMG changes failed to correlate significantly with changes in self reports of subjective relaxation derived from pre-to-post session state anxiety test data. The possibility that the ineffectiveness of visual feedback in this study may be specific to the frontalis muscle was discussed and the need for further research in several areas was stressed.     

Effect of Feedback Sensitivity Upon Learned Heart Rate Acceleration

Twelve undergraduate volunteers received 12 sessions of heart rate biofeedback training involving one of two experimental conditions. One-half of the subjects received 4 sessions of high sensitivity analogue heart rate biofeedback, followed by 4 sessions of low sensitivity feedback, and then, 4 final sessions of high sensitivity feedback. The other half of the subjects received the exact opposite order of feedback conditions. All subjects were instructed to accelerate heart rate during 8 trials in each session. The results were contrary to the hypothesis derived from a motor skills model of visceral learning, i.e., the low feedback sensitivity condition consistently produced larger magnitude heart rate acceleration in comparison to the high sensitivity condition. These findings were discussed in terms of methodological suggestions for future research and in terms of the motor skills model of visceral learning.     

Motor unit recruitment strategy changes with skill acquisition

The modifications of motor unit recruitment strategy due to skill acquisition was determined in the elbow flexor-extensor muscles of normal human subjects. The median frequency of the power density spectra of the electromyograms recorded from the biceps and triceps muscles during a 3-s linear increase in flexion force in the range of 0–100% maximal voluntary contraction (MVC) was calculated for each subject, every 2 weeks over a total 6-week period during which subjects practiced linear flexion force increase three times a week. Electromyograms were recorded with two pairs of electrodes of different size and electrode spacing. It was shown that skill acquisition due to the 360 practice trials over the 6-week period caused an increase in the initial motor unit recruitment phase of the agonist's force generation cycle from about 0–65% MVC to about 0–85% MVC. The increase in the recruitment range was gradual and statistically significant for the measurements made every 2 weeks. The reccruitment range of the antagonist triceps demonstrated a minor, but statistically insignificant, decrease over the same training period. There was a minor, but statistically significant, advantage of using small electrodes and inter-electrode spacing. It was concluded that skill acquisition, due to repeated functional use of a muscle in the same contraction mode, results in a slower, prolonged recruitment of motor units in the initial segment of the force generation cycle, thereby allowing a more precise and accurate control of the increments of force increase. Such conclusions reinforce the concept advocating the plasticity of motor unit control according to the functional demands imposed on the muscle. The results have significant implications in the design of various athletic, occupational and rehabilitation training modalities for optimal performance of various movement functions.     

Relaxation Training and Biofeedback in the Reduction of Reducation Muscle Tension

To assess the comparative effectiveness of frontalis electromygraphic (E M G) biofeedback and relaxation instructions in reducing frontalis EMG levels, 101 male and female university students were randomly assigned to one of the following groups: 1) frontalis EMG biofeedback (variable frequency auditory feedback). 2) passive relaxation instruct inns (instructions to attend to and relax mustiest. 3) active relaxation instructions tensing and relaxing exercises), 4) false feedback, and 5l no treatment control. In a one-session design, subjects receiving biofeedback and passive relaxation instructions demonstrated the greatest decrement in frontalis EMG level. The relationships between decrements in frontalis EMG level and sex, baseline EMG and manifest anxiety are discussed.     

运动单位电位的实时分类

用相关分析方法对运动单位电位进行实时分类，用对相关系数进行排序的方法保留波形较好的运动单位电位，以减少运动单位电位的存储量和分析时间，提高运动单位电位参数测量的准确性和精确性。     

Effect of Feedback Delay Upon Learned Heart Rate Control

The effects of heart rate feedback delay upon bidirectional heart rate control were determined by comparing four groups of 10 subjects who received either: a) immediate feedback, or b) feedback that was delayed by 1.4 sec, 5 sec, or 14 sec. All subjects received 3 sessions of training which included 3 within-session phases, i.e. 2 (pre and post-feedback) Instructional Control phases during which subjects were instructed to speed or slow heart rate without the aid of feedback, and a Feedback phase during which bidirectional heart rate control was assisted by analogue heart rate feedback. Heart rate, chin EMG, and respiration rate were recorded during all phases. The results indicated that the magnitude of heart rate increases and decreases was systematically influenced by differing amounts of feedback delay. For increasing and decreasing heart rate, the group receiving immediate feedback showed superior heart rate control in comparison to groups which received feedback that was delayed by 14 sec. The strongest effects of feedback delay were evident during Feedback and the final Instructional Control phase. Only the group receiving immediate feedback improved HR control during Feedback and post-feedback Instructional Control phases. These findings were discussed in terms of a motor skills learning model for learned HR control. It was concluded that while many of the same parameters influence HR and motoric behavior, the two responses should not be regarded as equivalent.     

An Experimental Test of Assumptions Relating to the Use of Electromyographic Biofeedbatk as a General Relaxation Training Technique

Twenty-eight normal adults participated in an experimental test of two assumptions underlying the use of electromyographic (EMG) biofeedback as a general relaxation training technique: (1) that trained EMG reduction in one muscle generalizes to untrained muscles; and (2) that subjective feelings of relaxation are related to EMG reduction. An experimental group received 5 sessions, during the middle 3 of which EMG biofeedback training was offered on the frontalis muscle. Throughout all sessions, EMG recordings were also taken from the forearm and lower leg, and ratings of subjective relaxation feelings were obtained at regular intervals. A control group, matched with the experimental group on baseline frontalis EMG, received 5 similar sessions without feedback. Employing a maximum p of .05, the results revealed no evidence of generalization of EMG reduction from the frontalis to the untrained sites, nor any tendency for successful frontalis EMG reduction to result in increased feelings of relaxation beyond what was obtainable from relaxing without the benefit of training. The results were interpreted as suggesting that EMG biofeedback cannot yet be accepted as a viable general relaxation training technique.     

Single motor unit and spectral surface EMG analysis during low-force, sustained contractions of the upper trapezius muscle

Intramuscular and surface electromyographic (EMG) activities were recorded from the left and right upper trapezius muscle of eight healthy male subjects during 5-min long static contractions at 2% and 5% of the maximal voluntary contraction (MVC) force. Intramuscular signals were detected by wire electrodes while surface EMG signals were recorded with linear adhesive electrode arrays. The surface EMG signals were averaged using the potentials extracted from the intramuscular EMG decomposition as triggers. The conduction velocity of single motor units (MUs) was estimated over time from the averaged surface potentials while average rectified value and mean power spectral frequency were computed over time from 0.5 s epochs of surface EMG signal. It was found that (1) MUs were progressively recruited after the beginning of sustained contractions of the upper trapezius muscle at 2% and 5% MVC, (2) the conduction velocity of the MUs active since the beginning of the contraction significantly decreased over time, and (3) although the CV of single MUs significantly decreased, the mean power spectral frequency of the surface EMG did not show a consistent trend over time. It was concluded that spectral surface EMG analysis, being affected by many physiological mechanisms, may show limitations for the objective assessment of localized muscle fatigue during low force, sustained contractions. On the contrary, single motor unit conduction velocity may provide an early indication of changes in muscle fiber membrane properties with sustained activity.     

Training and Transfer of Training Effects in EMG Biofeedback Assisted Muscular Relaxation

Twenty-two normal adults participated in an electromyographic (EMG) biofeedback experiment designed to test if the feedback stimulus is necessary in obtaining EMG reductions during typical laboratory procedures, and if prior training on one muscle facilitates the training of a second muscle. One group of subjects received forearm feedback training followed by frontalis training. A second group received training in the reverse order. Two control groups relaxed first on their own followed by either forearm or frontalis training. Attention was directed toward motivating control subjects to perform maximally during relaxation without feedback. Heart and respiration rates and skin conductance and temperature were also recorded. Both trained and untrained subjects produced significant EMG reductions but did not differ from each other; nor did a transfer of training effect emerge. No differences resulted between feedback and non-feedback conditions for the other physiological measures or for changes in state anxiety. These data compromise somewhat the previous demonstrations of EMG biofeedback “learning,” and are unsupportive of EMG biofeedback as a general relaxation training technique.     

The Acquisition of Autonomic Control Through Biofeedback: The Case Against an Afferent Process and a Two-Process Alternative

Brener has proposed a general theory of the development of voluntary control which offers as its focus an account of the process underlying the acquisition of control over autonomic responses. This account views the acquisition process as consequent to the development of the subject's ability to discriminate afferentation related to the response state to be produced and to his formulating an appropriate response image on the basis of this afferentation. The paper begins with an extensive review of biofeedback studies pertinent to the theory. This review yields little convincing evidence for Brener's views. Selected studies on the performance and the acquisition of motor skills and on the nature of the image are then examined. These suggest that the development of control of a response may rely primarily on efferent processes, with afferent processes playing, at most, a secondary role. A two-process theory of the acquisition of autonomic control is then presented. The theory proposes that, in most instances, biofeedback training leads to autonomic control through a process consisting primarily in the identification of efferent behavioural programmes already within the subject's repertoire. The theory further proposes that an afferent acquisition process such as postulated by Brener may also underlie the development of autonomic control, but only under conditions where behavioural programmes effective in controlling the target response are either unavailable or inaccessible to the subject.     

Simultaneous EMGs From Six Sites During Muscular Relaxation: A Comparison Between Forehead and Forearm Feedback

In light of the continuing popularity of frontalis EMG feedback for general relaxation purposes, a pertinent question is whether this procedure is superior to feedback from other muscles. This question was addressed by comparing a frontalis feedback group (n = 12) with a forearm feedback group (n = 10) in a one-session experiment. The experimental session included a 10-min rest period preceded by verbal relaxation instructions and demonstration of the respective feedback contingencies, and followed by a 30-min feedback period. EMG records were obtained from forehead, forearm, neck, masseter, sternomastoid, and lower leg. In the two target muscles, significant group differences developed during rest, but no additional significant effects were produced during feedback. Regarding the four untrained sites, EMG tended to decrease in the forehead group, but not significantly below the levels of the forearm group. Simultaneous EMG cross-correlations within 5-min intervals based on successive 1-sec averages showed significant covariation between muscles in the head and neck area; the source of this covariation was uncertain, however—electrical “crosstalk” and generalized muscular responding were two possibilities discussed.     

Synthesising of a motor unit potential based on the sequential firing of muscle fibres

A model for the summation of the fibre potentials in a motor unit is presented. A possible mechanism for the recruitment sequence of the various fibres of a motor unit is developed on the basis of anatomical and physiological findings supplemented with a mathematical approach making it possible to take into consideration the spatial and temporal distribution of various fibre potentials. In addition to the commonly accepted parameters of a motor unit potential, stress is laid on the relative position of the recording electrode with respect to the structure of the motor unit and the location of the motor point of the muscle. The model is evaluated both with dipole and dielectric attenuation approaches. The sub-unit concept of a motor unit is critically examined in the light of the results of the model. Attention has been focused on the motor units of the brachial biceps, but the flexibility of the approach also makes it possible to consider motor units of other muscles. The procedure for such generalisations and the respective limitations are discussed. The model provides a unified approach to the diversity of the parameters of the motor unit potential.     

Motor unit firing variability and synchronization during short-term light-load training in older adults

We compared motor unit synchronization and firing rate variability within and across synergistic hand muscles during a pinching task following short-term light-load training to improve force steadiness in older adults. A total of 183 motor unit pairs before training and 158 motor unit pairs after training were recorded with intramuscular fine-wire electrodes within and across the first dorsal interosseous (FDI) and adductor pollicis (AdP) muscles during a pinch task performed by ten older adults before and after a 4-week short-term light-load training program. Nine younger adults performed the same experimental sessions 4 weeks apart with no training intervention. Two-minute sustained contractions of 2, 4, 8, and 12% maximal voluntary contraction (MVC) were performed with the non-dominant hand. The coefficient of variation (CV) of force was greater in older than in younger adults and was lower at the 2 and 4% MVC levels in both the finger (0.12 ± 0.01 vs. 0.08 ± 0.01, and 0.08 ± 0.01 vs. 0.05 ± 0.01, respectively) and thumb (0.11 ± 0.01 vs. 0.08 ± 0.01, and 0.09 ± 0.01 vs. 0.05 ± 0.01, respectively) compared to higher force levels following training in the older adults. There were no changes in CIS or k’-1 values following training. Motor unit firing rate variability significantly decreased at low force levels in the FDI muscle and also tended to decrease with training in the AdP muscle (p = 0.06). No changes occurred in the younger control group. These findings are the first to show that motor unit synchronization does not change during light-load training. Thus, it is likely that force steadiness in older adults improves by reducing motor unit firing variability rather than by changing motor unit synchronization.     

自动分解肌电图运动单位动作电位各参数的分析和临床意义

目的：探讨运动单位动作电位（ＭＵＡＰ）各参数评价神经肌肉疾病的临床意义。方法：采用肌电图仪,以常规同心圆针电极记录,对７１例健康成人和４３例神经肌肉疾病患者的肱二头肌或／和胫前肌进行自动分解肌电图（ＡＤＥＭＧ）检测,共收集ＭＵＡＰ８３５６个,测定ＭＵＡＰ的５个参数：波幅、时限、转折数、发放率、棘波间隔变异系数（ＣＩＶ）。结果：１５例肌源性疾病患者表现为每一记录部位的ＭＵＡＰ数目增加;肱二头肌ＭＵＡＰ的波幅、时限、转折数减低、发放率增加,ＣＩＶ无改变;胫前肌ＭＵＡＰ的各参数无显著性改变。２８例神经源性疾病患者表现为每一记录部位的ＭＵＡＰ数目减少;ＭＵＡＰ的波幅、转折数及ＣＩＶ增加,时限及发放率无显著性增加。结论：ＡＤＥＭＧ检测的ＭＵＡＰ各参数对于评价神经肌肉疾病有重要的临床意义。     

Feedback and Instructions in the Control of Digital Skin Temperature

Fourteen female subjects suffering from idiopathic Raynaud's Disease were trained during 6 laboratory sessions to raise skin temperature. All subjects were given autogenic instructions and half the subjects were given skin temperature feedback from the middle digit of the dominant hand. Autogenic instructions were found to produce small but reliable increases in skin temperature regardless of whether or not feedback was provided. Following the autogenic instructions all subjects showed decreases in skin temperature. However, these decreases were greater for subjects not receiving feedback than for those receiving feedback. Theoretical implications of these data are discussed.     

反馈技术在运动功能康复治疗中的应用

反馈是执行运动功能过程中的非常重要的信息交换模式，它以体感信息、触觉信息、视觉信息、听觉信息等方式将运动过程的信息传送到中枢神经，调控运动功能执行的时间和空间精度。本文从反馈的作用原理、技术方法和治疗效果等方面，分析和综述了肌电信号反馈、机器人辅助运动康复训练、高级认知过程反馈及三维虚拟技术等几种反馈技术对运动功能康复治疗的作用。     

腹直肌肌电图运动单位电位正常值的建立

目的:建立腹直肌肌电图(EMG)运动单位动作电位(MUAP)各参数正常值。方法:测定109例正常人腹直肌EMG的MUAP的时限、波幅及多相波。结果:腹直肌EMG的MUAP参数分别为:波幅373．78±56．46μV,时限9．95±1．13 ms,多相波19．40％±1．52％。结论:腹直肌EMG各参数能可靠、稳定地测出,有助于脊髓胸段下运动神经元病变的检测。     

电极配置对MUAP检测影响的仿真研究

本研究采用模型的方法,研究了电极配置对运动单位动作电位检测的影响.根据肌肉的形态结构和生理特征,从细胞内动作电位开始,仿真了运动单位动作电位序列.在此基础上,研究了电极的配置对运动单位动作电位的波形和统计特征的影响.结果表明:尺寸较小的电极选择性较好;差分电极的选择性优于单电极,适当调整其电极间距离和角度,可提高检测质量.     

Feedback training of 36 - 44 HZ EEG activity in the visual cortex and hippocampus of cats: evidence for sensory and motor involvement

Milk reinforcement was contingent on the occurrence of 36 -44 (40) Hz EEG activity in the left visual cortex (VC) of one group of cats and in the right hippocampus (H) of a second group. Both groups learned to increase 40 Hz activity, and acquisition of reinforcement was associated with immobility. A third group (behavioral controls - BC) was trained by the method of successive approximation to behave in a similar manner to VC and H cats. Training significantly increased 40 Hz activity in all of the following structures, except the hippocampi of VC cats and between the right and left visual cortex of H and BC cats: posterior primary visual cortex (bilateral), anterior primary visual cortex (left), primary motor cortex (bilateral), dorsal hippocampus (bilateral), and midbrain reticular formation (bilateral). Since the behavioral and EEG changes of H and BC animals were similar, immobility appears to be important for increased hippocampal 40 Hz activity produced by feedback training. Testing in darkness enhanced 40 Hz activity in the trained area of VC cats but had no effect on H or BC animals. These results, in conjunction with the observation that VC cats appeared to visually fixate, suggest that VC cats may have learned to increase 40 Hz activity in the visual cortex by altering visual processing.