Impaired and preserved aspects of independent finger control in patients with cerebellar damage

2012 ◽  
Vol 107 (4) ◽  
pp. 1080-1093 ◽  
Author(s):  
B. Brandauer ◽  
J. Hermsdörfer ◽  
T. Geißendörfer ◽  
B. Schoch ◽  
E. R. Gizewski ◽  
...  
Keyword(s):  
Force Production ◽  
Middle Finger ◽  
Motor Command ◽  
Cerebellar Tumor ◽  
Cerebellar Damage ◽  
Patient Groups ◽  
Finger Forces ◽  
Lesion Symptom Mapping ◽  
Lift Off ◽  
Finger Control

The influence of the cerebellum on independent finger control has rarely been investigated. We examined multidigit control in 22 patients with cerebellar degeneration, 20 patients with cerebellar stroke, and 21 patients with surgical lesions after cerebellar tumor removal. In the first task, either the index finger or the middle finger was actively lifted from an object during static holding. Both controls and cerebellar patients increased the forces of the nearby digits in synchrony with lift-off to maintain the total finger force. Patients used increased finger forces but showed no significant deficits in the pattern and timing of rearrangement of finger forces. In the second task, subjects had to press and release one finger against a force-sensitive keypad with the other fingers being inactive. All patient groups showed increased force production of the noninstructed (enslaved) fingers compared with controls. Lesion-symptom mapping in the focal patients revealed that lesions of the superior hand area were related to abnormal levels of enslaving. Increased finger forces in the finger-lifting task likely reflect an unspecific safety strategy. Increased effects of enslaving in the individuated key-press task, however, may be explained by a deterioration of cerebellar contribution to feedforward commands necessary to suppress activity in noninstructed fingers or by increased spread of the motor command intended for the instructed finger. Despite the large and diverse patient sample, surprisingly few abnormalities were observed. Both holding an object and finger typing are overlearned, automatized motor tasks, which may not or little depend on the integrity of the cerebellum.

Control of Grasp Stability in Humans Under Different Frictional Conditions During Multidigit Manipulation

1999 ◽  
Vol 82 (5) ◽  
pp. 2393-2405 ◽  
Author(s):  
Magnus K. O. Burstedt ◽  
J. Randall Flanagan ◽  
Roland S. Johansson
Keyword(s):  
Load Distribution ◽  
Safety Margin ◽  
Middle Finger ◽  
The Other ◽  
Surface Material ◽  
Tangential Load ◽  
Normal Forces ◽  
Grasp Stability ◽  
Contact Surfaces ◽  
Lift Off

Control of grasp stability under different frictional conditions has primarily been studied in manipulatory tasks involving two digits only. Recently we found that many of the principles for control of forces originally demonstrated for two-digit grasping also apply to various three-digit grasps. Here we examine the control of grasp stability in a multidigit task in which subjects used the tips of the thumb, index, and middle finger to lift an object. The grasp resembled those used when lifting a cylindrical object from above. The digits either all contacted the same surface material or one of the digits contacted a surface material that was more, or less, slippery than that contacted by the other two digits. The three-dimensional forces and torques applied by each digit and the contact positions were measured along with the position and orientation of the object. The distribution of forces among the digits strongly reflected constraints imposed by the geometric relationship between the object's center of mass and the contact surfaces. On top of this distribution, we observed changes in force coordination related to changes in the combination of surface materials. When all digits contacted the same surface material, the ratio between the normal force and tangential load ( F n: L ratio) was similar across digits and scaled to provide an adequate safety margin against slip. With different contact surfaces subjects adapted the F n: L ratios at the individual digits to the local friction with only small influences by the friction at the other two digits. They accomplished this by scaling the normal forces similarly at all digits and changing the distribution of load among the digits. The surface combination did not, however, influence digit position, tangential torque, or object tilting systematically. The change in load distribution, rather, resulted from interplay between these factors, and the nature of this interplay varied between trials. That is, subjects achieved grasp stability with various combinations of fingertip actions and appeared to exploit the many degrees of freedom offered by the multidigit grasp. The results extend previous findings based on two-digit tasks to multidigit tasks by showing that subjects adjust fingertip forces at each digit to the local friction. Moreover, our findings suggest that subjects adapted the load distribution to the current frictional condition by regulating the normal forces to allow slips to occur early in the lift task, prior to object lift-off.

Spatial and Temporal Sequence Learning in Patients with Parkinson's Disease or Cerebellar Lesions

2003 ◽  
Vol 15 (8) ◽  
pp. 1232-1243 ◽  
Author(s):  
Jacqueline C. Shin ◽  
Richard B. Ivry
Keyword(s):  
Sequence Learning ◽  
Functional Role ◽  
Phase Relationship ◽  
Reaction Time Task ◽  
Training Sequence ◽  
Temporal Sequence ◽  
General Role ◽  
Cerebellar Damage ◽  
Patient Groups

The functional role of different subcortical areas in sequence learning is not clear. In the current study, Parkinson's patients, patients with cerebellar damage, and age-matched control participants performed a serial reaction time task in which a spatial sequence and a temporal sequence were presented simultaneously. The responses were based on the spatial sequence, and the temporal sequence was incidental to the task. The two sequences were of the same length, and the phase relationship between them was held constant throughout training. Sequence learning was assessed comparing performance when both sequences were present versus when the dimension of interest was randomized. In addition, sequence integration was assessed by introducing phase-shift blocks. A functional dissociation was found between the two patient groups. Whereas the Parkinson's patients learned the spatial and temporal sequences individually, they did not learn the relationship between the two sequences, suggesting the basal ganglia play a functional role in sequence integration. In contrast, the cerebellar patients did not show any evidence of sequence learning at all, suggesting the cerebellum might play a general role in forming sequential associations.

scholarly journals Equifinality and its violations in a redundant system: multifinger accurate force production

2013 ◽  
Vol 110 (8) ◽  
pp. 1965-1973 ◽  
Author(s):  
Luke Wilhelm ◽  
Vladimir M. Zatsiorsky ◽  
Mark L. Latash
Keyword(s):  
Force Production ◽  
Uncontrolled Manifold ◽  
Total Force ◽  
Redundant System ◽  
Uncontrolled Manifold Hypothesis ◽  
Final State ◽  
Performance Variables ◽  
Force Mode ◽  
Finger Forces ◽  
The Individual

We explored a hypothesis that transient perturbations applied to a redundant system result in equifinality in the space of task-related performance variables but not in the space of elemental variables. The subjects pressed with four fingers and produced an accurate constant total force level. The “inverse piano” device was used to lift and lower one of the fingers smoothly. The subjects were instructed “not to intervene voluntarily” with possible force changes. Analysis was performed in spaces of finger forces and finger modes (hypothetical neural commands to fingers) as elemental variables. Lifting a finger led to an increase in its force and a decrease in the forces of the other three fingers; the total force increased. Lowering the finger back led to a drop in the force of the perturbed finger. At the final state, the sum of the variances of finger forces/modes computed across repetitive trials was significantly higher than the variance of the total force/mode. Most variance of the individual finger force/mode changes between the preperturbation and postperturbation states was compatible with constant total force. We conclude that a transient perturbation applied to a redundant system leads to relatively small variance in the task-related performance variable (equifinality), whereas in the space of elemental variables much more variance occurs that does not lead to total force changes. We interpret the results within a general theoretical scheme that incorporates the ideas of hierarchically organized control, control with referent configurations, synergic control, and the uncontrolled manifold hypothesis.

scholarly journals Stability of multifinger action in different state spaces

2014 ◽  
Vol 112 (12) ◽  
pp. 3209-3218 ◽  
Author(s):  
Sasha Reschechtko ◽  
Vladimir M. Zatsiorsky ◽  
Mark L. Latash
Keyword(s):  
Force Production ◽  
Total Force ◽  
Force Output ◽  
Large Magnitude ◽  
State Spaces ◽  
Theoretical Scheme ◽  
Lower Stability ◽  
Mode Space ◽  
Finger Forces

We investigated stability of action by a multifinger system with three methods: analysis of intertrial variance, application of transient perturbations, and analysis of the system's motion in different state spaces. The “inverse piano” device was used to apply transient (lifting-and-lowering) perturbations to individual fingers during single- and two-finger accurate force production tasks. In each trial, the perturbation was applied either to a finger explicitly involved in the task or one that was not. We hypothesized that, in one-finger tasks, task-specific stability would be observed in the redundant space of finger forces but not in the nonredundant space of finger modes (commands to explicitly involved fingers). In two-finger tasks, we expected that perturbations applied to a nontask finger would not contribute to task-specific stability in mode space. In contrast to our expectations, analyses in both force and mode spaces showed lower stability in directions that did not change total force output compared with directions that did cause changes in total force. In addition, the transient perturbations led to a significant increase in the enslaving index. We consider these results within a theoretical scheme of control with referent body configurations organized hierarchically, using multiple few-to-many mappings organized in a synergic way. The observed volatility of enslaving, greater equifinality of total force compared with elemental variables, and large magnitude of motor equivalent motion in both force and mode spaces provide support for the concept of task-specific stability of performance and the existence of multiple neural loops, which ensure this stability.

Modeling constraints to redundancy in bimanual force coordination

2011 ◽  
Vol 105 (5) ◽  
pp. 2169-2180 ◽  
Author(s):  
Xiaogang Hu ◽  
Karl M. Newell
Keyword(s):  
Muscle Force ◽  
Coupling Effect ◽  
Isometric Force ◽  
Force Production ◽  
Force Output ◽  
Task Constraints ◽  
Task Goal ◽  
Force Coordination ◽  
Finger Forces ◽  
Coordination Patterns

This study investigated the interactive influence of organismic, environmental, and task constraints on the organization of redundant force coordination patterns and the hypothesis that each of the three categories of constraints is weighted based on their relative influence on coordination patterns and the realization of the task goal. In the bimanual isometric force experiment, the task constraint was manipulated via different coefficients imposed on the finger forces such that the weighted sum of the finger forces matched the target force. We examined three models of task constraints based on the criteria of task variance (minimum variance model) and efficiency of muscle force output (coefficient-independent and coefficient-dependent efficiency models). The environmental constraint was quantified by the perceived performance error, and the organismic constraint was quantified by the bilateral coupling effect (i.e., symmetric force production) between hands. The satisficing approach was used in the models to quantify the constraint weightings that reflect the interactive influence of different categories of constraints on force coordination. The findings showed that the coefficient-dependent efficiency model best predicted the redundant force coordination patterns across trials. However, the within-trial variability structure revealed that there was not a consistent coordination strategy in the online control of the individual trial. The experimental findings and model tests show that the force coordination patterns are adapted based on the principle of minimizing muscle force output that is coefficient dependent rather than on the principle of minimizing signal-dependent variance. Overall, the results support the proposition that redundant force coordination patterns are organized by the interactive influence of different categories of constraints.

Prediction and Compensation by an Internal Model for Back Forces During Finger Opening in an Overarm Throw

1999 ◽  
Vol 82 (3) ◽  
pp. 1187-1197 ◽  
Author(s):  
J. Hore ◽  
S. Watts ◽  
D. Tweed
Keyword(s):  
Internal Model ◽  
Middle Finger ◽  
Proximal Interphalangeal Joint ◽  
Force Transducers ◽  
Ball Release ◽  
Overarm Throw ◽  
Finger Motion ◽  
The Moment ◽  
Finger Control ◽  
Overarm Throws

Previous studies have indicated that timing of finger opening in an overarm throw is likely controlled centrally, possibly by means of an internal model of hand trajectory. The present objective was to extend the study of throwing to an examination of the dynamics of finger opening. Throwing a heavy ball and throwing a light ball presumably require different neural commands, because the weight of the ball affects the mechanics of the arm, and particularly, the mechanics of the finger. Yet finger control is critical to the accuracy of an overarm throw. We hypothesized that finger opening in an overarm throw is controlled by a central mechanism that uses an internal model to predict and compensate for movement-dependent back forces on the fingers. To test this idea we determined whether finger motion is affected by back forces, i.e., whether larger back forces cause larger finger extensions. Back forces were varied by having subjects throw, at the same fast speed, tennis-sized balls of different weights (14, 55, and 196 g). Arm- and finger-joint rotations were recorded with the search-coil technique; forces on the middle finger were measured with force transducers. Recordings showed that during ball release, the middle finger experienced larger back forces in throws with heavier balls. Nevertheless, most subjects showed proximal interphalangeal joint extensions that were unchanged or actually smaller with the heavier balls. This was the case for the first throw and for all subsequent throws with a ball of a new weight. This suggests that the finger flexors compensated for the larger back forces by exerting larger torques during finger extension. Supporting this view, at the moment of ball release, all finger joints flexed abruptly due to the now unopposed torques of the finger flexors, and the amplitude of this flexion was proportional to ball weight. We conclude that in overarm throws made with balls of different weights, the CNS predicts the different back forces from the balls and adjusts finger flexor torques accordingly. This is consistent with the view that finger opening in overarm throws is controlled by means of an internal model of the motor apparatus and the external load.

Interaction between Finger Force and Neural Command in Multi-Finger Force Production

2006 ◽  
Vol 326-328 ◽  
pp. 751-754
Author(s):  
Yoon Hyuk Kim
Keyword(s):  
Mathematical Model ◽  
Force Production ◽  
Voluntary Contraction ◽  
Finger Force ◽  
Healthy Male ◽  
Hand Biomechanics ◽  
Single Finger ◽  
Finger Forces ◽  
The Relationship ◽  
Male Subjects

In this study, we investigated the relationship between the finger force and the neural command in multi-finger force production tasks in order to characterize the neural enslaving effect and the force-deficit effect among fingers. Seven healthy male subjects were instructed to press one, two, three and four fingers on the finger sensors as hard as possible acting in parallel in all possible combinations. Then, the finger forces in each task were recorded and analyzed to represent the neural enslaving effect and the force-deficit effect. The results confirmed that individual finger forces were smaller in multi-finger maximal voluntary contraction tasks than in single-finger tasks. The force deficit effect increased with the number of fingers involved. A mathematical model proposed in this paper based on the experimental results could explicitly describe the two effects of finger interaction by representing the relationship between the neural commands and finger forces. The present results could be useful information to understand the basic neuro-muscular mechanism in hand biomechanics and the fundamentals of intelligent hand robots.

scholarly journals Taboo gesticulations as a response to pain

2019 ◽  
Vol 19 (2) ◽  
pp. 397-406
Author(s):  
Maarten Jacobs ◽  
Ilja van Beest ◽  
Richard Stephens
Keyword(s):  
Pain Perception ◽  
Index Finger ◽  
Cold Pressor ◽  
Middle Finger ◽  
Pain Tolerance ◽  
Cold Pressor Task ◽  
Main Effect ◽  
Lower Pain ◽  
Finger Control ◽  
Ice Water

Abstract Background and aims Prior research indicates that swearing increases pain tolerance and decreases pain perception in a cold pressor task. In two experiments, we extend this research by testing whether taboo hand gesticulations have a similar effect. Methods Study 1 focused on males and females who, across two trials, submerged an extended middle finger (taboo) and an extended index finger (control) in ice water until discomfort necessitated removal. Study 2 focused exclusively on pain perception in males who, across three trials, submerged their hand, flat, with extended middle finger and with extended index finger, for 45 s each. Results In study 1 taboo gesticulation did not increase pain tolerance or reduce pain perception compared with the index finger control condition, as a main effect or as part of an interaction with condition order. While there was a gesture×gender interaction for pain tolerance, this was driven by an increased pain tolerance for the index finger gesture for women but not men. The results of study 2 again showed that taboo gesticulation did not lower pain perception, although it did increase positive affect compared with both non-taboo gesture conditions. Conclusions Taken together these results provide only limited evidence that taboo gesticulation alters the experience of pain. These largely null findings further our understanding of swearing as a response to pain, suggesting that the activation of taboo schemas is not sufficient for hypoalgesia to occur.

scholarly journals On the nature of unintentional action: a study of force/moment drifts during multifinger tasks

2016 ◽  
Vol 116 (2) ◽  
pp. 698-708 ◽  
Author(s):  
Behnoosh Parsa ◽  
Daniel J. O'Shea ◽  
Vladimir M. Zatsiorsky ◽  
Mark L. Latash
Keyword(s):  
Visual Feedback ◽  
Sensory Information ◽  
Force Production ◽  
Total Force ◽  
Total Moment ◽  
Individual Finger ◽  
Referent Coordinate ◽  
Force Moment ◽  
Finger Forces ◽  
The Right

We explored the origins of unintentional changes in performance during accurate force production in isometric conditions seen after turning visual feedback off. The idea of control with referent spatial coordinates suggests that these phenomena could result from drifts of the referent coordinate for the effector. Subjects performed accurate force/moment production tasks by pressing with the fingers of a hand on force sensors. Turning the visual feedback off resulted in slow drifts of both total force and total moment to lower magnitudes of these variables; these drifts were more pronounced in the right hand of the right-handed subjects. Drifts in individual finger forces could be in different direction; in particular, fingers that produced moments of force against the required total moment showed an increase in their forces. The force/moment drift was associated with a drop in the index of synergy stabilizing performance under visual feedback. The drifts in directions that changed performance (non-motor equivalent) and in directions that did not (motor equivalent) were of about the same magnitude. The results suggest that control with referent coordinates is associated with drifts of those referent coordinates toward the corresponding actual coordinates of the hand, a reflection of the natural tendency of physical systems to move toward a minimum of potential energy. The interaction between drifts of the hand referent coordinate and referent orientation leads to counterdirectional drifts in individual finger forces. The results also demonstrate that the sensory information used to create multifinger synergies is necessary for their presence over the task duration.

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