Influence of age on proprioceptive accuracy in two dimensions

Proprioceptive accuracy in Immersive Virtual Reality: A developmental perspective

Proprioceptive development relies on a variety of sensory inputs, among which vision is hugely dominant. Focusing on the developmental trajectory underpinning the integration of vision and proprioception, the present research explores how this integration is involved in interactions with Immersive Virtual Reality (IVR) by examining how proprioceptive accuracy is affected by Age, Perception, and Environment. Individuals from 4 to 43 years old completed a self-turning task which asked them to manually return to a previous location with different sensory modalities available in both IVR and reality. Results were interpreted from an exploratory perspective using Bayesian model comparison analysis, which allows the phenomena to be described using probabilistic statements rather than simplified reject/not-reject decisions. The most plausible model showed that 4-8-year-old children can generally be expected to make more proprioceptive errors than older children and adults. Across age groups, proprioceptive accuracy is higher when vision is available, and is disrupted in the visual environment provided by the IVR headset. We can conclude that proprioceptive accuracy mostly develops during the first eight years of life and that it relies largely on vision. Moreover, our findings indicate that this proprioceptive accuracy can be disrupted by the use of an IVR headset.

Hand Recognition Obtained by Simulation of Hand Regard

Eye-hand coordination of an infant is observed during the early months of their development. Hand regard, which is an example of this coordination, occurs at about 2 months. It is considered that after experiencing hand regard, an infant may recognize their own hands. However, it is unknown how an infant recognizes their hands through hand regard. Accordingly, the process by which an infant recognizes their hands and distinguishes between their hands and other objects was simulated. A simple neural network was trained with a modified real-time recurrent learning (RTRL) algorithm to deal with time-varying input and output during hand regard. The simulation results show that information about recognition of the modeled hands of an infant is stored in cell assemblies, which were self-organized. Cell assemblies appear during the phase of U-shaped developments of hand regard, and the configuration of the cell assemblies changes with each U-shaped development. Furthermore, movements like general movements (GMs) appear during the phase of U-shaped developments of hand regard.

The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force

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.

Development of upper limb proprioceptive accuracy in children and adolescents

This study was designed to determine differences in the proprioceptively guided movements of children (8-10 years) and adolescents (16-18 years). Participants were blindfolded and asked to actively match passively determined target positions of the elbow joint under three matching conditions. Overall, children were less accurate than adolescents in all matching tasks and utilized different kinematic strategies for making the matching movements. Specifically, children made larger absolute errors and utilized matching movements which, compared to adolescents, were of shorter duration and less irregular in terms of their velocity profiles. An assessment of limb asymmetry was also performed revealing a non-dominant arm matching advantage but only for children and only in the task requiring interhemispheric transfer of a memory-based model of limb position. The proprioceptive differences observed in this study are likely the result of experience-driven refinement in the utilization of somatosensory feedback throughout childhood and into adolescence.

Assessment of Upper Limb Neuromuscular Control via a Target-Pointing Task: A Reliability Study

Objective:

To examine the accuracy and reliability of upper limb target pointing among normal subjects.

Design:

Prospective observational.

Setting:

Community sports-medicine practice.

Participants:

28 male and female normal right-handed volunteers age 22–35 years.

Intervention:

8-point target-pointing task completed with both upper limbs.

Main Outcome Measures:

Accuracy of point reproduction (cm error) and reliability over time (ICC2,1).

Results:

Target-pointing errors were 4.8–9.9 cm. Subject error and reach height explained 88% of performance variability. Error was greater when pointing to the lower half of the target (P< .05) and to ipsilateral points (P< .05). Gender, test day, reach length, and arm dominance did not affect accuracy. Test–retest reliability ranged from .30 to .71.

Conclusion:

Target-pointing tasks might be useful to assess upper limb neuromuscular control. Points with lower errors and greater reliabilities might be useful to differentiate normal vs abnormal performances, whereas a battery of reliable points over a spectrum of errors might be useful to document changes over time.

Discriminating overhead points of contact after arm raising

Arm-raising movements at the shoulder made to overhead locations were investigated in a weight-hearing stance with forward vision available. When discrimination of different points of contact was measured after arm elevations to the unseen overhead targets, no dominant arm advantage was found, but contacts made after the shortest (90 degrees) arm-elevation movements were better discriminated than those from arm-at-side (180 degrees), plus windup (540 degrees).

School screening for scoliosis: the value of quantitative measurement

Several studies advocate quantification of the bending test or performing surface topography to reduce the referral rate and to increase the specificity of the bending test in screening for scoliosis. Within the framework of a school screening project all children with a positive bending test were reexamined with measurement of rib hump height, angle of trunk rotation and moiré topography. In the period 1983-1986, out of three cohorts of 10,000 children of 10, 12 and 14 years of age, 3,069 were reexamined, of whom 1931 again tested positive (63%). The value of the three techniques in terms of sensitivity and specificity within the reexamined group was evaluated with regard to the Cobb angle on a spinal radiograph, which was made in 671 cases. A reduction in referrals of 37% was found. No significant difference in the ability to detect scoliosis was found between the three techniques mentioned. It is concluded that measurement techniques are valuable in school screening programmes. In particular, if instead of a single cut-off value, a range within which the examination should be repeated is chosen, high sensitivity and high specificity can be combined. Angle of trunk rotation measurement seems to be the easiest method of screening.