Detection of simultaneous movement at two human arm joints

Sturnieks, Daina L.; Wright, Julie R.; Fitzpatrick, Richard C.

doi:10.1113/jphysiol.2007.139089

Cited by 31 publications

(19 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Furthermore, smaller muscles will have a higher motor command to force ratio and a motor command signal may be more useful here than in larger, proximal muscles. It could also be that the distal muscles make more use of the additional information from central commands because these muscles tend to cross more joints, at times making muscle spindle information potentially ambiguous (Sturnieks et al 2007; see also Goodwin et al 1972). This argument cannot be used for wrist muscles versus elbow muscles as both cross a similar number of joints.…”

Section: Discussionmentioning

confidence: 99%

The contribution of motor commands to position sense differs between elbow and wrist

Walsh

Proske

Allen

et al. 2013

The Journal of Physiology

View full text Add to dashboard Cite

Key points• Knowing the position of our limbs is critical for accurate movement. Central motor command signals generated by the brain contribute to position sense at the human wrist, but this could not be demonstrated at the elbow.• We tested whether this represents a fundamental difference between the two joints or whether it reflects the two different methods used to measure position sense.• For both measurement methods, contraction of wrist muscles led to illusions that the wrist is displaced. No such illusions were detected at the elbow during muscle contraction.• Thus, the contribution of centrally generated command signals to position sense differs between joints. Any contribution at the elbow joint is small and new methods will be needed to reveal it.Abstract Recent studies have suggested that centrally generated motor commands contribute to the perception of position and movement at the wrist, but not at the elbow. Because the wrist and elbow experiments used different methods, this study was designed to resolve the discrepancy. Two methods were used to test both the elbow and wrist (20 subjects each). For the wrist, subjects sat with their right arm strapped to a device that restricted movement to the wrist. Before each test, voluntary contraction of wrist flexor or extensor muscles controlled for muscle spindle thixotropy. After relaxation, the wrist was moved to a test angle. Position was indicated either with a pointer, or by matching with the contralateral wrist, under two conditions: when the reference wrist was relaxed or when its muscles were contracted isometrically (30% maximum). The elbow experiment used the same design to measure position sense in the passive elbow and with elbow muscles contracting (30% maximum). At the wrist when using a pointer, muscle contraction altered significantly the perceived wrist angle in the direction of contraction by 7

show abstract

Section: Discussionmentioning

confidence: 99%

The contribution of motor commands to position sense differs between elbow and wrist

Walsh

Proske

Allen

et al. 2013

The Journal of Physiology

View full text Add to dashboard Cite

show abstract

“…We determined the detection threshold by a method that is frequently used to determine thresholds for detecting joint movements (Sturnieks et al 2006). Subjects were presented with the same reference and test stiffness pair 10 times with the order randomised.…”

Section: Methodsmentioning

confidence: 99%

Postural control at the human wrist

Chew

Gandevia

Fitzpatrick

2008

The Journal of Physiology

Self Cite

View full text Add to dashboard Cite

In our movements and posture, we always act against a physical load. A key property of any load is its elastic stiffness (K ), which describes how the force required to hold it must change with position. Here we examine how load stiffness affects the ability to maintain a stable posture at the wrist. Loads having positive (like a spring) and negative stiffness (like an inverted pendulum) were created by varying the position of weights on multiarm rigid pendulum. Subjects (n = 9) held 15 loads (K = ± 0.04, ± 0.01 and 0 N m deg −1 at mean torques of 0.2, 0.4 and 0.6 N m) still for 60 s. Residual wrist movement (sway) increased with mean torque and increased as stiffness became more negative. Large effects of load stiffness were seen at low frequencies (< 1.5 Hz) but not at higher frequencies that reflect load resonance and reflex activity. Subjects accurately perceived their postural sway while holding the loads but measured psychophysical thresholds showed that load stiffness was not perceived. We conclude that load stiffness, independent of force levels, affects the ability to control a load and that the postural control process relies on perception and volitional tracking rather than more automatic reflex pathways. Despite an awareness of their postural errors, we see no evidence for adaptation of postural control processes to compensate for changes in load properties. This is unlike the adaptation of feedforward control processes that produce targeted volitional movements when load properties are altered. We propose that postural control and movement control are fundamentally different neural processes.

show abstract

“…Here signals from muscle spindles are potentially ambiguous (see also Refs. 347,373). The presence of skin receptors adjacent to each finger joint allows them to provide joint-specific information (e.g., Refs.…”

Section: E Skin Receptorsmentioning

confidence: 99%

The Proprioceptive Senses: Their Roles in Signaling Body Shape, Body Position and Movement, and Muscle Force

Proske

Gandevia

2012

Physiological Reviews

1,508

1,261

View full text Add to dashboard Cite

This is a review of the proprioceptive senses generated as a result of our own actions. They include the senses of position and movement of our limbs and trunk, the sense of effort, the sense of force, and the sense of heaviness. Receptors involved in proprioception are located in skin, muscles, and joints. Information about limb position and movement is not generated by individual receptors, but by populations of afferents. Afferent signals generated during a movement are processed to code for endpoint position of a limb. The afferent input is referred to a central body map to determine the location of the limbs in space. Experimental phantom limbs, produced by blocking peripheral nerves, have shown that motor areas in the brain are able to generate conscious sensations of limb displacement and movement in the absence of any sensory input. In the normal limb tendon organs and possibly also muscle spindles contribute to the senses of force and heaviness. Exercise can disturb proprioception, and this has implications for musculoskeletal injuries. Proprioceptive senses, particularly of limb position and movement, deteriorate with age and are associated with an increased risk of falls in the elderly. The more recent information available on proprioception has given a better understanding of the mechanisms underlying these senses as well as providing new insight into a range of clinical conditions.

show abstract

Detection of simultaneous movement at two human arm joints

Cited by 31 publications

References 43 publications

The contribution of motor commands to position sense differs between elbow and wrist

The contribution of motor commands to position sense differs between elbow and wrist

Postural control at the human wrist

The Proprioceptive Senses: Their Roles in Signaling Body Shape, Body Position and Movement, and Muscle Force

Contact Info

Product

Resources

About