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Discordant Tasks and Motor Adjustments Affect Interactions between Adaptations to Altered Kinematics and Dynamics.

Arce F, Novick I, Vaadia E - Front Hum Neurosci (2010)

Bottom Line: We found a gradient of interaction effects based on perturbation direction and task discordance.We also found that force field and visuomotor rotation had mutual anterograde and retrograde effects.Such overlap does not necessarily imply competition of resources.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Hadassah Medical School, Hebrew University Jerusalem, Israel.

ABSTRACT
Motor control and adaptation are multi-determinate processes with complex interactions. This is reflected for example in the ambiguous nature of interactions during sequential adaptation of reaching under kinematics and dynamics perturbations. It has been suggested that perturbations based on the same kinematic parameter interfere. Others posited that opposing motor adjustments underlie interference. Here, we examined the influence of discordances in task and in motor adjustments on sequential adaptations to visuomotor rotation and viscous force field perturbations. These two factors - perturbation direction and task discordance - have been examined separately by previous studies, thus the inherent difficulty to identify the roots of interference. Forty-eight human subjects adapted sequentially to one or two types of perturbations, of matched or conflicting directions. We found a gradient of interaction effects based on perturbation direction and task discordance. Perturbations of matched directions showed facilitation while perturbations of opposite directions, which required opposing motor adjustments, interfered with each other. Further, interaction effects increased with greater task discordance. We also found that force field and visuomotor rotation had mutual anterograde and retrograde effects. However, we found independence between anterograde and retrograde interferences between similar tasks. The results suggest that the newly acquired internal models of kinematic and dynamic perturbations are not independent but they share common neuronal resources and interact between them. Such overlap does not necessarily imply competition of resources. Rather, our results point to an additional principle of sensorimotor adaptation allowing the system to tap or harness common features across diverse sensory inputs and task contexts whenever available.

No MeSH data available.


Related in: MedlinePlus

Interaction effects between sequential adaptations. (A) Improvement indexes (IMPs) reflecting anterograde effects of prior adaptation onto a subsequent adaptation to force field (F) or rotation (R) of matched (m) or non-matched (n) direction. (B) Retrograde IMPs reflecting degree of retention of the first task learned in the sequence. IMPs from the control force (CF) and control rotation (CR) groups were also plotted (gray). Note the gradient as combinations vary in task discordance and perturbation direction. (C) Anterograde effects on the path curvature of subsequent force fields or subsequent rotations. (D) As in B but for retrograde IMPs of path curvature. Error bars are ± 1 SEM. Numbered connecting bars depict comparisons between groups in the order of appearance in the text. Asterisks denote significance at least p < 0.01.
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Figure 5: Interaction effects between sequential adaptations. (A) Improvement indexes (IMPs) reflecting anterograde effects of prior adaptation onto a subsequent adaptation to force field (F) or rotation (R) of matched (m) or non-matched (n) direction. (B) Retrograde IMPs reflecting degree of retention of the first task learned in the sequence. IMPs from the control force (CF) and control rotation (CR) groups were also plotted (gray). Note the gradient as combinations vary in task discordance and perturbation direction. (C) Anterograde effects on the path curvature of subsequent force fields or subsequent rotations. (D) As in B but for retrograde IMPs of path curvature. Error bars are ± 1 SEM. Numbered connecting bars depict comparisons between groups in the order of appearance in the text. Asterisks denote significance at least p < 0.01.

Mentions: When directions were matched, improvement indices (IMPs) were positive and significantly different from zero (t-Test, p < 0.0001, Figure 5A), indicating anterograde facilitation by prior adaptation onto the subsequent one. Interestingly, the facilitation by prior force field did not differ whether task B was similar or different from task A (Figure 5A, compare mF vs. mFR (1), ANOVA p < 0.0001, post-hoc Tukey Kramer p > 0.10), suggesting some overlap in the compensatory trajectory adjustments required by force field and rotation.


Discordant Tasks and Motor Adjustments Affect Interactions between Adaptations to Altered Kinematics and Dynamics.

Arce F, Novick I, Vaadia E - Front Hum Neurosci (2010)

Interaction effects between sequential adaptations. (A) Improvement indexes (IMPs) reflecting anterograde effects of prior adaptation onto a subsequent adaptation to force field (F) or rotation (R) of matched (m) or non-matched (n) direction. (B) Retrograde IMPs reflecting degree of retention of the first task learned in the sequence. IMPs from the control force (CF) and control rotation (CR) groups were also plotted (gray). Note the gradient as combinations vary in task discordance and perturbation direction. (C) Anterograde effects on the path curvature of subsequent force fields or subsequent rotations. (D) As in B but for retrograde IMPs of path curvature. Error bars are ± 1 SEM. Numbered connecting bars depict comparisons between groups in the order of appearance in the text. Asterisks denote significance at least p < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2806051&req=5

Figure 5: Interaction effects between sequential adaptations. (A) Improvement indexes (IMPs) reflecting anterograde effects of prior adaptation onto a subsequent adaptation to force field (F) or rotation (R) of matched (m) or non-matched (n) direction. (B) Retrograde IMPs reflecting degree of retention of the first task learned in the sequence. IMPs from the control force (CF) and control rotation (CR) groups were also plotted (gray). Note the gradient as combinations vary in task discordance and perturbation direction. (C) Anterograde effects on the path curvature of subsequent force fields or subsequent rotations. (D) As in B but for retrograde IMPs of path curvature. Error bars are ± 1 SEM. Numbered connecting bars depict comparisons between groups in the order of appearance in the text. Asterisks denote significance at least p < 0.01.
Mentions: When directions were matched, improvement indices (IMPs) were positive and significantly different from zero (t-Test, p < 0.0001, Figure 5A), indicating anterograde facilitation by prior adaptation onto the subsequent one. Interestingly, the facilitation by prior force field did not differ whether task B was similar or different from task A (Figure 5A, compare mF vs. mFR (1), ANOVA p < 0.0001, post-hoc Tukey Kramer p > 0.10), suggesting some overlap in the compensatory trajectory adjustments required by force field and rotation.

Bottom Line: We found a gradient of interaction effects based on perturbation direction and task discordance.We also found that force field and visuomotor rotation had mutual anterograde and retrograde effects.Such overlap does not necessarily imply competition of resources.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Neurobiology, The Institute for Medical Research Israel-Canada, Hadassah Medical School, Hebrew University Jerusalem, Israel.

ABSTRACT
Motor control and adaptation are multi-determinate processes with complex interactions. This is reflected for example in the ambiguous nature of interactions during sequential adaptation of reaching under kinematics and dynamics perturbations. It has been suggested that perturbations based on the same kinematic parameter interfere. Others posited that opposing motor adjustments underlie interference. Here, we examined the influence of discordances in task and in motor adjustments on sequential adaptations to visuomotor rotation and viscous force field perturbations. These two factors - perturbation direction and task discordance - have been examined separately by previous studies, thus the inherent difficulty to identify the roots of interference. Forty-eight human subjects adapted sequentially to one or two types of perturbations, of matched or conflicting directions. We found a gradient of interaction effects based on perturbation direction and task discordance. Perturbations of matched directions showed facilitation while perturbations of opposite directions, which required opposing motor adjustments, interfered with each other. Further, interaction effects increased with greater task discordance. We also found that force field and visuomotor rotation had mutual anterograde and retrograde effects. However, we found independence between anterograde and retrograde interferences between similar tasks. The results suggest that the newly acquired internal models of kinematic and dynamic perturbations are not independent but they share common neuronal resources and interact between them. Such overlap does not necessarily imply competition of resources. Rather, our results point to an additional principle of sensorimotor adaptation allowing the system to tap or harness common features across diverse sensory inputs and task contexts whenever available.

No MeSH data available.


Related in: MedlinePlus