Age-related changes in finger coordination in static prehension tasks

Shim, Jae Kun; Lay, Brendan; Zatsiorsky, Vladimir M.; Latash, Mark L.

doi:10.1152/japplphysiol.00045.2004

Cited by 157 publications

(162 citation statements)

References 45 publications

Supporting

Mentioning

136

Contrasting

Order By: Relevance

“…Similar observations have been reported in studies of multi-finger synergies involved in stabilization of the time profiles of the total force and total moment of force (Latash et al 2001;Scholz et al 2002;Shim et al 2004). Those studies have suggested that the control of two performance variables with the same set of effectors may be based on a principle of superposition (Arimoto et al 2001;Zatsiorsky et al 2004).…”

Section: Stabilization Of Two Performance Variables By the Same Set Osupporting

confidence: 79%

Multi-muscle synergies in an unusual postural task: quick shear force production

2008

Self Cite

View full text Add to dashboard Cite

We considered a hypothetical two-level hierarchy participating in the control of vertical posture. The framework of the uncontrolled manifold (UCM) hypothesis was used to explore the muscle groupings (M-modes) and multi-M-mode synergies involved in stabilization of a time profile of the shear force in the anterior-posterior direction. Standing subjects were asked to produce pulses of shear force into a target using visual feedback while trying to minimize the shift of the center of pressure (COP). Principal component analysis applied to integrated muscle activation indices identified three Mmodes. The composition of the M-modes was similar across subjects and the two directions of the shear force pulse. It differed from the composition of M-modes described in earlier studies of more natural actions associated with large COP shifts. Further, the trial-to-trial M-mode variance was partitioned into two components: one component that does not affect a particular performance variable (V UCM ), and its orthogonal component (V ORT ). We argued that there is a multi-M-mode synergy stabilizing this particular performance variable if V UCM is higher than V ORT . Overall, we found a multi-M-mode synergy stabilizing both shear force and COP coordinate. For the shear force, this synergy was strong for the backward force pulses and non significant for the forward pulses. An opposite result was found for the COP coordinate: the synergy was stronger for the forward force pulses. The study shows that M-mode composition can change in a task-specific way and that two different performance variables can be stabilized using the same set of elemental variables (Mmodes). The different dependences of the ΔV indices for the shear force and COP coordinate on the force pulse direction supports applicability of the principle of superposition (separate controllers for different performance variables) to the control of different mechanical variables in postural tasks. The M-mode composition allows a natural mechanical interpretation.

show abstract

Section: Stabilization Of Two Performance Variables By the Same Set Osupporting

confidence: 79%

Multi-muscle synergies in an unusual postural task: quick shear force production

2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…Previous studies using the UCM approach have found age-related differences in the structure of variability in multifinger force production (Olafsdottir et al, 2007;Shim et al, 2004;Shinohara et al, 2004), with weaker synergies in older compared with younger adults. Latash (2008) argued that constraining the use of motor abundance (leading to lower synergy indexes) may be an adaptive strategy to cope with age-related decline in sensorimotor processing and increasing neuromuscular noise (Enoka et al, 2003).…”

Section: Introductionmentioning

confidence: 91%

Normal aging reduces motor synergies in manual pointing

Verrel

Lövdén

Lindenberger

2012

Neurobiology of Aging

View full text Add to dashboard Cite

Depending upon its organization, movement variability may reflect poor or flexible control of a motor task. We studied adult age-related differences in the structure of postural variability in manual pointing using the uncontrolled manifold (UCM) method. Participants from 2 age groups (younger: 20 -30 years; older: 70 -80 years; 12 subjects per group) completed a total of 120 pointing trials to 2 different targets presented according to 3 schedules: blocked, alternating, and random. The age groups were similar with respect to basic kinematic variables, end point precision, as well as the accuracy of the biomechanical forward model of the arm. Following the uncontrolled manifold approach, goal-equivalent and nongoal-equivalent components of postural variability (goal-equivalent variability [GEV] and nongoal-equivalent variability [NGEV]) were determined for 5 time points of the movements (start, 10%, 50%, 90%, and end) and used to define a synergy index reflecting the flexibility/stability aspect of motor synergies. Toward the end of the movement, younger adults showed higher synergy indexes than older adults. Effects of target schedule were not reliable. We conclude that normal aging alters the organization of common multidegree-of-freedom movements, with older adults making less flexible use of motor abundance than younger adults.

show abstract

“…Reports on differences in the production of maximal torques in PR and SU have been inconsistent (Timm et al 1993;Gallagher et al 1997;Shim et al 2004b;Matsuoka et al 2006). To be safe, the magnitude of the target peak moment of force in our study was purposefully set at a relatively low value to both avoid fatigue and make sure that it was easy for the subjects to produce the required range of the moment magnitudes in both PR and SU.…”

Section: Rotational Efforts Into Pronation and Supinationmentioning

confidence: 99%

“…Such excessive antagonist moment production may be viewed as a sign of worse finger coordination; higher antagonist moments during maximal moment production tasks were reported for elderly subjects as compared to younger subjects (Shim et al 2004b). This excessive antagonist moment production was accompanied by higher total forces produced in SU phases of the main task and higher indices of force variability (possibly related to the well known relation between force and force variability; reviewed in Newell 1991).…”

Section: Rotational Efforts Into Pronation and Supinationmentioning

confidence: 99%

See 1 more Smart Citation

Finger synergies during multi-finger cyclic production of moment of force

2006

Self Cite

View full text Add to dashboard Cite

We investigated multi-finger synergies stabilizing the total moment of force and the total force when the subjects produced a quick cyclic change in the total moment of force. The seated subjects performed the task with the fingers of the dominant arm while paced by the metronome at 1.33 Hz. They were required to produce a rhythmic, sine-like change in the total pronation-supination moment of force computed with respect to the midpoint between the middle and ring fingers. The framework of the uncontrolled manifold hypothesis was used to compute indices of stabilization of the total moment and of the total force across 20 cycles. Variance of the total moment showed a cyclic pattern with peaks close to the peak rate of the moment change. Variance of the total force was maximal close to peak moment into supination. Higher magnitudes of the moment directed against the required moment direction (antagonist moment) were produced by individual fingers during supination efforts as compared to pronation efforts. Indices of multi-finger synergies showed across-trials stabilization of the total moment over the whole cycle but not of the total force. These indices were smaller during supination efforts. We conclude that the central nervous system facilitates multi-finger synergies stabilizing the total rotational action across a variety of tasks. Synergies stabilizing the total force are not seen in tasks that do not explicitly require accurate force control. Pronation efforts are performed more efficiently and with better stabilization of the action.

show abstract

Age-related changes in finger coordination in static prehension tasks

Cited by 157 publications

References 45 publications

Multi-muscle synergies in an unusual postural task: quick shear force production

Multi-muscle synergies in an unusual postural task: quick shear force production

Normal aging reduces motor synergies in manual pointing

Finger synergies during multi-finger cyclic production of moment of force

Contact Info

Product

Resources

About