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Age-Specific Effects of Mirror-Muscle Activity on Cross-Limb Adaptations Under Mirror and Non-Mirror Visual Feedback Conditions.

Reissig P, Stöckel T, Garry MI, Summers JJ, Hinder MR - Front Aging Neurosci (2015)

Bottom Line: Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1).For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60).In this particular task, MVF did not facilitate the extent of CLT.

View Article: PubMed Central - PubMed

Affiliation: Human Motor Control Laboratory, School of Medicine, Faculty of Health, University of Tasmania Hobart, TAS, Australia ; Faculty of Health Graduate Research Program, University of Tasmania Hobart, TAS, Australia.

ABSTRACT
Cross-limb transfer (CLT) describes the observation of bilateral performance gains due to unilateral motor practice. Previous research has suggested that CLT may be reduced, or absent, in older adults, possibly due to age-related structural and functional brain changes. Based on research showing increases in CLT due to the provision of mirror visual feedback (MVF) during task execution in young adults, our study aimed to investigate whether MVF can facilitate CLT in older adults, who are known to be more reliant on visual feedback for accurate motor performance. Participants (N = 53) engaged in a short-term training regime (300 movements) involving a ballistic finger task using their dominant hand, while being provided with either visual feedback of their active limb, or a mirror reflection of their active limb (superimposed over the quiescent limb). Performance in both limbs was examined before, during and following the unilateral training. Furthermore, we measured corticospinal excitability (using TMS) at these time points, and assessed muscle activity bilaterally during the task via EMG; these parameters were used to investigate the mechanisms mediating and predicting CLT. Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1). Training also elicited bilateral increases in corticospinal excitability (p < 0.05). For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60). The present study suggests that older adults are capable of exhibiting CLT to a similar degree to younger adults. The prominent role of mirror activity in the untrained hand for CLT in older adults indicates that bilateral cortical activity during unilateral motor tasks is a compensatory mechanism. In this particular task, MVF did not facilitate the extent of CLT.

No MeSH data available.


Related in: MedlinePlus

Simple Correlation (i.e., zero-order Correlation) between the change of performance in the untrained hand at post-test (ΔACCuntrained) and (a) the change of performance in the trained hand during training (ΔACCtraining; left side) and (b) the average amount of EMG activity exhibited in the untrained hand (lnEMGtraininguntrained) during training (right side) for the younger group (top row) and the older group (bottom row).
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Figure 5: Simple Correlation (i.e., zero-order Correlation) between the change of performance in the untrained hand at post-test (ΔACCuntrained) and (a) the change of performance in the trained hand during training (ΔACCtraining; left side) and (b) the average amount of EMG activity exhibited in the untrained hand (lnEMGtraininguntrained) during training (right side) for the younger group (top row) and the older group (bottom row).

Mentions: Separate multiple regression analyses were employed to identify significant predictors of ΔACCuntrained for the younger and the older adults. For the older adults, analysis revealed that ΔACCuntrained was significantly predicted by both models (i.e., with and without inclusion of the test-related variables—see “Materials and Methods” Section). The model excluding the test-related variables revealed a better fit and significance (adjusted R2 = 0.51, F(2,19) = 11.81, p < 0.001) than the model including all (i.e., test and training) variables (adjusted R2 = 0.50, F(6, 15) = 4.47, p = 0.009). In the younger adults ΔACCuntrained was significantly predicted by the model that included the training-related variables (adjusted R2 = 0.17, F(2,22) = 3.51, p = 0.047), but not by the model that was complemented by the test-related variables (ΔR2 = 0.19, ΔF(4, 18) = 1.54, Δp = 0.233). In the older adults, lnEMGtraininguntrained, β = 0.604, t(2,19) = 3.83, p = 0.001, uniquely accounted for a significant portion of the variance in ΔACCuntrained, explaining 36.5% of the variance. In addition, nACCtraining was marginally associated with changes in ΔACCuntrained, β = 0.315, t(2,19) = 2.00, p = 0.061, explaining a further 9.9% of the variance. In the younger adults, only nACCtraining accounted for a significant portion of the variance in ΔACCuntrained, β = 0.496, t(2,22) = 2.63, p = 0.015, explaining 24.6% of the variance (Figure 5).


Age-Specific Effects of Mirror-Muscle Activity on Cross-Limb Adaptations Under Mirror and Non-Mirror Visual Feedback Conditions.

Reissig P, Stöckel T, Garry MI, Summers JJ, Hinder MR - Front Aging Neurosci (2015)

Simple Correlation (i.e., zero-order Correlation) between the change of performance in the untrained hand at post-test (ΔACCuntrained) and (a) the change of performance in the trained hand during training (ΔACCtraining; left side) and (b) the average amount of EMG activity exhibited in the untrained hand (lnEMGtraininguntrained) during training (right side) for the younger group (top row) and the older group (bottom row).
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Figure 5: Simple Correlation (i.e., zero-order Correlation) between the change of performance in the untrained hand at post-test (ΔACCuntrained) and (a) the change of performance in the trained hand during training (ΔACCtraining; left side) and (b) the average amount of EMG activity exhibited in the untrained hand (lnEMGtraininguntrained) during training (right side) for the younger group (top row) and the older group (bottom row).
Mentions: Separate multiple regression analyses were employed to identify significant predictors of ΔACCuntrained for the younger and the older adults. For the older adults, analysis revealed that ΔACCuntrained was significantly predicted by both models (i.e., with and without inclusion of the test-related variables—see “Materials and Methods” Section). The model excluding the test-related variables revealed a better fit and significance (adjusted R2 = 0.51, F(2,19) = 11.81, p < 0.001) than the model including all (i.e., test and training) variables (adjusted R2 = 0.50, F(6, 15) = 4.47, p = 0.009). In the younger adults ΔACCuntrained was significantly predicted by the model that included the training-related variables (adjusted R2 = 0.17, F(2,22) = 3.51, p = 0.047), but not by the model that was complemented by the test-related variables (ΔR2 = 0.19, ΔF(4, 18) = 1.54, Δp = 0.233). In the older adults, lnEMGtraininguntrained, β = 0.604, t(2,19) = 3.83, p = 0.001, uniquely accounted for a significant portion of the variance in ΔACCuntrained, explaining 36.5% of the variance. In addition, nACCtraining was marginally associated with changes in ΔACCuntrained, β = 0.315, t(2,19) = 2.00, p = 0.061, explaining a further 9.9% of the variance. In the younger adults, only nACCtraining accounted for a significant portion of the variance in ΔACCuntrained, β = 0.496, t(2,22) = 2.63, p = 0.015, explaining 24.6% of the variance (Figure 5).

Bottom Line: Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1).For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60).In this particular task, MVF did not facilitate the extent of CLT.

View Article: PubMed Central - PubMed

Affiliation: Human Motor Control Laboratory, School of Medicine, Faculty of Health, University of Tasmania Hobart, TAS, Australia ; Faculty of Health Graduate Research Program, University of Tasmania Hobart, TAS, Australia.

ABSTRACT
Cross-limb transfer (CLT) describes the observation of bilateral performance gains due to unilateral motor practice. Previous research has suggested that CLT may be reduced, or absent, in older adults, possibly due to age-related structural and functional brain changes. Based on research showing increases in CLT due to the provision of mirror visual feedback (MVF) during task execution in young adults, our study aimed to investigate whether MVF can facilitate CLT in older adults, who are known to be more reliant on visual feedback for accurate motor performance. Participants (N = 53) engaged in a short-term training regime (300 movements) involving a ballistic finger task using their dominant hand, while being provided with either visual feedback of their active limb, or a mirror reflection of their active limb (superimposed over the quiescent limb). Performance in both limbs was examined before, during and following the unilateral training. Furthermore, we measured corticospinal excitability (using TMS) at these time points, and assessed muscle activity bilaterally during the task via EMG; these parameters were used to investigate the mechanisms mediating and predicting CLT. Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1). Training also elicited bilateral increases in corticospinal excitability (p < 0.05). For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60). The present study suggests that older adults are capable of exhibiting CLT to a similar degree to younger adults. The prominent role of mirror activity in the untrained hand for CLT in older adults indicates that bilateral cortical activity during unilateral motor tasks is a compensatory mechanism. In this particular task, MVF did not facilitate the extent of CLT.

No MeSH data available.


Related in: MedlinePlus