| 1. |
- Djupsjöbacka, Mats, et al.
(författare)
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Correlation analysis of proprioceptive acuity in ipsilateral position-matching and velocity-discrimination.
- 2005
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Ingår i: Somatosensory & motor research. - : Informa UK Limited. - 0899-0220 .- 1369-1651. ; 22:1-2, s. 85-93
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Tidskriftsartikel (refereegranskat)abstract
- In order to plan and control movements the central nervous system (CNS) needs to continuously keep track of the state of the musculoskeletal system. Therefore the CNS constantly uses sensory input from mechanoreceptors in muscles, joints and skin to update information about body configuration on different levels of the CNS. On the conscious level, such representations constitute proprioception. Different tests for assessment of proprioceptive acuity have been described. However, it is unclear if the proprioceptive acuity measurements in these tests correlate within subjects. By using both uni- and multivariate analysis we compared proprioceptive acuity in different variants of ipsilateral active and passive limb position-matching and ipsilateral passive limb movement velocity-discrimination in a group of healthy subjects. The analysis of the position-matching data revealed a higher acuity of matching for active movements in comparison to passive ones. The acuity of matching was negatively correlated to movement extent. There was a lack of correlation between proprioceptive acuity measurements in position-matching and velocity-discrimination.
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| 2. |
- Domkin, Dmitry, et al.
(författare)
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Ciliary muscle contraction force and trapezius muscle activity during manual tracking of a moving visual target
- 2016
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Ingår i: Journal of Electromyography and Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 28, s. 193-198
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown an association of visual demands during near work and increased activity of the trapezius muscle. Those studies were conducted under stationary postural conditions with fixed gaze and artificial visual load. The present study investigated the relationship between ciliary muscle contraction force and trapezius muscle activity across individuals during performance of a natural dynamic motor task under free gaze conditions. Participants (N = 11) tracked a moving visual target with a digital pen on a computer screen. Tracking performance, eye refraction and trapezius muscle activity were continuously measured. Ciliary muscle contraction force was computed from eye accommodative response. There was a significant Pearson correlation between ciliary muscle contraction force and trapezius muscle activity on the tracking side (0.78, p < 0.01) and passive side (0.64, p < 0.05). The study supports the hypothesis that high visual demands, leading to an increased ciliary muscle contraction during continuous eye–hand coordination, may increase trapezius muscle tension and thus contribute to the development of musculoskeletal complaints in the neck–shoulder area. Further experimental studies are required to clarify whether the relationship is valid within each individual or may represent a general personal trait, when individuals with higher eye accommodative response tend to have higher trapezius muscle activity.
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| 3. |
- Domkin, Dmitry, et al.
(författare)
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Distraction of Eye-Hand Coordination Varies With Working Memory Capacity
- 2013
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Ingår i: Journal of motor behavior. - : Taylor and Francis (Psychology Press) / Taylor and Francis (Routledge): STM, Behavioural Science and Public Health Titles. - 0022-2895 .- 1940-1027. ; 45:1, s. 79-83
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Tidskriftsartikel (refereegranskat)abstract
- The authors present a study of the relationship between individual variation in working memory capacity (WMC) and visually guided hand control in the face of visual distraction. WMC was assessed with the automated operation span task. Hand control was measured by requesting participants to track a visual target with a hand-held touch screen pen. Tracking error increased when nontarget visual objects (distractors) appeared, especially in individuals with low WMC. High-WMC individuals are less impaired by distractors than their low-WMC counterpart, because they resume target tracking more quickly after distractor onset. The results suggest that visual distractors cause a momentary interruption to tracking movements and that high WMC attenuates this interruption by facilitating visual search.
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| 4. |
- Domkin, Dmitry, et al.
(författare)
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Effect of ciliary-muscle contraction force on trapezius muscle activity during computer mouse work
- 2019
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Ingår i: European Journal of Applied Physiology. - : SPRINGER. - 1439-6319 .- 1439-6327. ; 119:2, s. 389-397
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Tidskriftsartikel (refereegranskat)abstract
- The present study aimed to identify whether or not an increase in ciliary-muscle contraction force, when the eye-lens is adjusted for viewing at a near distance, results in an increase in trapezius muscle activity, while performing a natural work task. Twelve participants, ranging in age from 21 to 32years, performed a computer-mouse work task during free gaze conditions. A moving visual target was tracked with a computer mouse on a screen placed at two different distances from the eyes, 25cm and 50cm. Tracking performance, eye accommodation, and bilateral trapezius muscle activity were measured continuously. Ciliary-muscle contraction force was computed according to a formula which takes into account the age-dependent, non-linear relationship between the contraction force of the ciliary muscle and the produced level of eye accommodation. Generalized estimating equations analyses were performed. On the dominant hand side and for the nearest screen distance, there was a significant effect of ciliary-muscle contraction force on the trapezius muscle activity (p<0.001). No other effects were significant (p>0.05). The results support the hypothesis that high visual demands, during computer mouse work, increase ciliary muscle contraction force and contribute to a raise of the sustained level of trapezius muscle activity. The current study specifically clarifies the validity of the relationship between ciliary-muscle contraction force and trapezius muscle activity and demonstrates that this relationship is not due to a general personality trait. We conclude that a high level of ciliary muscle contraction force can contribute to a development of musculoskeletal complaints in the neck-shoulder area.
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| 5. |
- Domkin, Dmitry, et al.
(författare)
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Effect of reduced visual acuity on precision of two-dimensional tracing movements
- 2016
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Ingår i: Journal of Optometry. - Madrid, España : Spanish Council of Optometry. - 1888-4296. ; 9:2, s. 93-101
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We intended to assess consequences of reduced visual acuity for performance in a natural simple motor task (tracing) using objective kinematic performance measures. Specifically, we intended to elucidate the kind of relationship between the task performance and best corrected binocular visual acuity and to determine the threshold of visual acuity when task performance starts to deteriorate.Methods: Ninety-five individuals with different best corrected visual acuity participated in the study (age 49±12 years, mean±SD, 27 men and 68 women). The participants manually traced maze-like visual patterns of different spatial complexity presented on the screen of a portable notebook computer using Clinical Kinematic Assessment Tool software. Tracing error was computed as performance measure in each trial with a spatial pattern matching technique - rigid point set registration method.Results: The segmented linear regression analysis showed that the relation between visual acuity and tracing errors was best described with a regression function having a break point between two data segments. Tracing performance was unaffected by values of visual acuity below 0.2 on logMAR scale, but when logMAR values increased above this critical limit (i.e. when visual acuity is further reduced), tracing errors linearly increased. The rate of the increase of the tracing error correlated with the complexity of visual stimulus shape.Conclusion: Testing of fine motor functions with objective kinematic measures during visuomotor tasks may help differentiating between actual effects of reduced visual acuity on eye-hand coordination in individuals with similar levels of impairment of visual acuity.
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| 6. |
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| 7. |
- Domkin, Dmitry, et al.
(författare)
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Joint angle variability in 3D bimanual pointing : uncontrolled manifold analysis.
- 2005
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Ingår i: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 163:1, s. 44-57
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Tidskriftsartikel (refereegranskat)abstract
- The structure of joint angle variability and its changes with practice were investigated using the uncontrolled manifold (UCM) computational approach. Subjects performed fast and accurate bimanual pointing movements in 3D space, trying to match the tip of a pointer, held in the right hand, with the tip of one of three different targets, held in the left hand during a pre-test, several practice sessions and a post-test. The prediction of the UCM approach about the structuring of joint angle variance for selective stabilization of important task variables was tested with respect to selective stabilization of time series of the vectorial distance between the pointer and aimed target tips (bimanual control hypothesis) and with respect to selective stabilization of the endpoint trajectory of each arm (unimanual control hypothesis). The components of the total joint angle variance not affecting (V(COMP)) and affecting (V(UN)) the value of a selected task variable were computed for each 10% of the normalized movement time. The ratio of these two components R(V)=V(COMP)/V(UN) served as a quantitative index of selective stabilization. Both the bimanual and unimanual control hypotheses were supported, however the R(V) values for the bimanual hypothesis were significantly higher than those for the unimanual hypothesis applied to the left and right arm both prior to and after practice. This suggests that the CNS stabilizes the relative trajectory of one endpoint with respect to the other more than it stabilizes the trajectories of each of the endpoints in the external space. Practice-associated improvement in both movement speed and accuracy was accompanied by counter-intuitive lack of changes in R(V). Both V(COMP) and V(UN) variance components decreased such that their ratio remained constant prior to and after practice. We conclude that the UCM approach offers a unique and under-explored opportunity to track changes in the organization of multi-effector systems with practice and allows quantitative assessment of the degree of stabilization of selected performance variables.
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| 8. |
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| 9. |
- Domkin, Dmitry, et al.
(författare)
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Outcomes of ipsilateral position matching and velocity discrimination are uncorrelated
- 2003
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Ingår i: Sensorimotor Coordination, behavioural modes and neural mechanisms. - Fraser Island, Australia.
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Konferensbidrag (refereegranskat)abstract
- The central nervous system processes sensory input from proprioceptors to form a state estimate of body configuration, which represents proprioception on theconscious level. Proprioception can be divided in two submodalities: sense of movement and sense of position. It is unclear whether tests, involving psychophysical methods and assessing proprioceptive acuity, can separate between perception of movement and position and thus, measure specific proprioception submodalities. In order to investigate if position matching and velocity discrimination tests can separate perception of position and perception of movement, correlations between outcomes of these tests were analyzed. Sixteen young healthy right-handed and gender balanced subjects performed movements in the right glenohumeral joint in all tests. In the ipsilateral position matching test subjects replicated an arm location, achieved in a criterion movement. Movements were performed from positions Q, 4Q and 80- degrees to target positions 16, 32, 48 and 64 degrees with respect to the body sagittal plane. Four conditions, different in terms of movement mode to the target position during criterion and replication movement, were used: passive-active, passive-passive, active-active, semipassive-semipassive. In the latter condition subjects slightly resisted the passive movement. In the ipsilateral velocity discrimination test subjects assessed if a latter comparison arm movement was faster or slower than a previous criterion movement. Criterion movements were performed at velocities of 3Q and 5Q deg/s. T wo conditions were used: passive-passive and semipassive-semipassive. Variable errors (VE) andjust noticeable differences (JND) were measures of proprioceptive acuity in the position matching and velocity discrimination, respectively. Hierarchical cluster analysis (H CA) and principal component analysis (PCA) were applied to study correlations between outcomes in conditions of both tests. In the H CA solution, the position matchi ng and velocity discrimination conditions were located in clusters on opposite poles of the cluster structure. The PCA results were interpreted for six significant components. The position matching and velocity discrimination conditions loaded mainly on components one to five and on component six, respectively. Both the H CA and the PCA separated all test conditions in t wo groups: one contained the position matching and another the velocity discrimination conditions. There were no clear differences between conditions within each group. The study showed that the outcomes VE and JND of the position matching and velocity discrimination, respectively, are mainly uncorrelated. This implies that these tests likely measure different proprioceptive perceptual components or their different combinations. The position matching and velocity discrimination tests could in general separate between perception of position and movement, although no direct evidence was obtained for ex act match of each test with specific proprioception submodality. Much clearer separation of the measured outcomes could be achieved in subjects, heterogeneous with respect to proprioceptive acuity, i.e. with larger variability of performance.
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| 10. |
- Domkin, Dmitry
(författare)
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Perception and control of upper limb movement: Insights gained by analysis of sensory and motor variability
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chronic neck-shoulder pain is associated with impairments of proprioception and motor control. Thus, assessment of proprioceptive and motor function may be powerful tools both for research and clinical practice. However, insufficient knowledge of certain features of human sensorimotor control hampers both development and interpretation of results of clinically relevant tests. For example, evidence is lacking which proprioception submodalities are reflected in common tests of proprioception. For testing motor function, a better understanding of the control of goal directed arm movements is needed. The purpose of the thesis was to gain further insights into the sensorimotor control of the upper limb in healthy subjects, with implications for clinical testing. The main aims were: (1) to study relationships of outcomes of different tests of shoulder proprioception and (2) to study control strategies in bimanual pointing tasks by analysis of the structure of joint angle variability with the Uncontrolled Manifold (UCM) method. Correlations between proprioceptive acuity in different variants of ipsilateral position-matching and velocity-discrimination were studied. The main finding was that two uncorrelated mechanisms based either on perception of position or movement might underlie perception of limb location in ipsilateral position-matching. The results provided important information for interpretation of common and development of novel tests of shoulder proprioception. The structure of joint angle variance was computed with respect to several task variables during bimanual pointing. Joint angle variability was decomposed in variance affecting and not affecting a task variable. The results showed that the variance in joint space was structured according to the predictions of the UCM hypothesis. It was also shown that the arms were united into one synergy to significantly larger degree than joints within each arm were united into single-arm synergies. It was concluded that the UCM approach might quantify components of motor variability during repetitive motor tasks.
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