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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

Normalized and back transformed (nMEP) amplitudes evoked in the first dorsal interosseus (FDI) of the trained and the untrained hand for the younger (left side) and the older (right side) groups at pre-, mid-, and post-test. Error bars denote SEM.
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Figure 4: Normalized and back transformed (nMEP) amplitudes evoked in the first dorsal interosseus (FDI) of the trained and the untrained hand for the younger (left side) and the older (right side) groups at pre-, mid-, and post-test. Error bars denote SEM.

Mentions: An initial analysis on MEP revealed no significant main effects or interactions (all F < 1.74, all p > 0.194). Since the assumption of normality was violated (on the nMEP variable) log transformation was undertaken (i.e., lnnMEP) prior to further analysis. The analysis revealed a significant main effect of time, F(1,44) = 4.11, p = 0.049, = 0.084, with greater lnnMEP at post-test (M = 0.35 [0.24, 0.47]) compared to mid-test (M = 0.25 [0.14, 0.37]). In addition, an interpretation of 95% CI’s indicated that MEP was greater at mid-test than at pre-test for both the trained hand (M = 0.32 [0.16, 0.48]) and the untrained hand (M = 0.19 [0.034, 0.35]). Analysis further revealed a trend for hand × feedback interaction, F(1,44) = 4.01, p = 0.051, = 0.082. Post hoc comparisons revealed significantly higher lnnMEP in the hemisphere responsible for the trained hand (M = 0.49 [0.28, 0.69]) compared to the hemisphere responsible for the untrained hand (M = 0.13 [−0.09, 0.35]) in the AV condition, p = 0.025, d = 0.192. No other significant main effects or interactions were found (all F < 1.70, all p > 0.199; Figure 4).


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)

Normalized and back transformed (nMEP) amplitudes evoked in the first dorsal interosseus (FDI) of the trained and the untrained hand for the younger (left side) and the older (right side) groups at pre-, mid-, and post-test. Error bars denote SEM.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4664666&req=5

Figure 4: Normalized and back transformed (nMEP) amplitudes evoked in the first dorsal interosseus (FDI) of the trained and the untrained hand for the younger (left side) and the older (right side) groups at pre-, mid-, and post-test. Error bars denote SEM.
Mentions: An initial analysis on MEP revealed no significant main effects or interactions (all F < 1.74, all p > 0.194). Since the assumption of normality was violated (on the nMEP variable) log transformation was undertaken (i.e., lnnMEP) prior to further analysis. The analysis revealed a significant main effect of time, F(1,44) = 4.11, p = 0.049, = 0.084, with greater lnnMEP at post-test (M = 0.35 [0.24, 0.47]) compared to mid-test (M = 0.25 [0.14, 0.37]). In addition, an interpretation of 95% CI’s indicated that MEP was greater at mid-test than at pre-test for both the trained hand (M = 0.32 [0.16, 0.48]) and the untrained hand (M = 0.19 [0.034, 0.35]). Analysis further revealed a trend for hand × feedback interaction, F(1,44) = 4.01, p = 0.051, = 0.082. Post hoc comparisons revealed significantly higher lnnMEP in the hemisphere responsible for the trained hand (M = 0.49 [0.28, 0.69]) compared to the hemisphere responsible for the untrained hand (M = 0.13 [−0.09, 0.35]) in the AV condition, p = 0.025, d = 0.192. No other significant main effects or interactions were found (all F < 1.70, all p > 0.199; Figure 4).

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