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The impact of aging on the spatial accuracy of quick corrective arm movements in response to sudden target displacement during reaching.

Kimura D, Kadota K, Kinoshita H - Front Aging Neurosci (2015)

Bottom Line: Results showed that, for the younger group, the variance in the directional error of the corrective response correlated with the variance in the reaching trajectory at the halfway point of the reach, but the correlation decreased at the end of the reaching.On the other hand, such correlations were not significant in elderly participants, although the variance of the directional error did not show a significant difference between age groups.Thus, the quick, corrective response seems to play an important role in decreasing variability, especially before the end of reaching, and aging can impair this process.

View Article: PubMed Central - PubMed

Affiliation: Biomechanics and Motor Control Laboratory, Graduate School of Medicine, Osaka University Toyonaka, Japan.

ABSTRACT
Age-related declines in visuomotor processing speed can have a large impact on motor performance in elderly individuals. Contrary to previous findings, however, recent studies revealed that elderly individuals are able to quickly react to displacement of a visual target during reaching. Here, we investigated the influence of aging on quick, corrective responses to perturbations during reaching in the terms of their functional contribution to accuracy. Elderly and young adults performed reaching movements to a visual target that could be displaced during reaching, and they were requested to move their hand to reach the final target location as quickly as possible. Results showed that, for the younger group, the variance in the directional error of the corrective response correlated with the variance in the reaching trajectory at the halfway point of the reach, but the correlation decreased at the end of the reaching. On the other hand, such correlations were not significant in elderly participants, although the variance of the directional error did not show a significant difference between age groups. Thus, the quick, corrective response seems to play an important role in decreasing variability, especially before the end of reaching, and aging can impair this process.

No MeSH data available.


Relationship between the variability in trajectory (i.e., hand marker location at the time when Y-velocity had decreased to 300 mm/s) and the variability in the directional differences for young (A) and elderly (B) participants. Relationship between the variability in the endpoint and the variability in the directional differences for young (C) and elderly (D) participants.
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Figure 5: Relationship between the variability in trajectory (i.e., hand marker location at the time when Y-velocity had decreased to 300 mm/s) and the variability in the directional differences for young (A) and elderly (B) participants. Relationship between the variability in the endpoint and the variability in the directional differences for young (C) and elderly (D) participants.

Mentions: To examine the contribution of TJR on reaching movement accuracy, relationships between the variability of the TJR directional difference and the spatial variability of the trajectory were examined at both of the halfway point and at the end of the reaching movements. Figures 5A,C show the relationships in the younger group. We found a strong relationship at the halfway point (r = 0.654, p = 0.0004; Figure 5A) but a weaker one at the end of reaching movements (r = 0.449, p = 0.002; Figure 5C). It appears that the variance of the reaching trajectory can affect the trajectory bias caused by TJR until a late phase of reaching, but that this variance is reduced at the fine tuning phase at the end of reaching. Thus, it seems that TJR can contribute a reduced trajectory variability, which is caused by an online corrective movement to compensate a target location change.


The impact of aging on the spatial accuracy of quick corrective arm movements in response to sudden target displacement during reaching.

Kimura D, Kadota K, Kinoshita H - Front Aging Neurosci (2015)

Relationship between the variability in trajectory (i.e., hand marker location at the time when Y-velocity had decreased to 300 mm/s) and the variability in the directional differences for young (A) and elderly (B) participants. Relationship between the variability in the endpoint and the variability in the directional differences for young (C) and elderly (D) participants.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585039&req=5

Figure 5: Relationship between the variability in trajectory (i.e., hand marker location at the time when Y-velocity had decreased to 300 mm/s) and the variability in the directional differences for young (A) and elderly (B) participants. Relationship between the variability in the endpoint and the variability in the directional differences for young (C) and elderly (D) participants.
Mentions: To examine the contribution of TJR on reaching movement accuracy, relationships between the variability of the TJR directional difference and the spatial variability of the trajectory were examined at both of the halfway point and at the end of the reaching movements. Figures 5A,C show the relationships in the younger group. We found a strong relationship at the halfway point (r = 0.654, p = 0.0004; Figure 5A) but a weaker one at the end of reaching movements (r = 0.449, p = 0.002; Figure 5C). It appears that the variance of the reaching trajectory can affect the trajectory bias caused by TJR until a late phase of reaching, but that this variance is reduced at the fine tuning phase at the end of reaching. Thus, it seems that TJR can contribute a reduced trajectory variability, which is caused by an online corrective movement to compensate a target location change.

Bottom Line: Results showed that, for the younger group, the variance in the directional error of the corrective response correlated with the variance in the reaching trajectory at the halfway point of the reach, but the correlation decreased at the end of the reaching.On the other hand, such correlations were not significant in elderly participants, although the variance of the directional error did not show a significant difference between age groups.Thus, the quick, corrective response seems to play an important role in decreasing variability, especially before the end of reaching, and aging can impair this process.

View Article: PubMed Central - PubMed

Affiliation: Biomechanics and Motor Control Laboratory, Graduate School of Medicine, Osaka University Toyonaka, Japan.

ABSTRACT
Age-related declines in visuomotor processing speed can have a large impact on motor performance in elderly individuals. Contrary to previous findings, however, recent studies revealed that elderly individuals are able to quickly react to displacement of a visual target during reaching. Here, we investigated the influence of aging on quick, corrective responses to perturbations during reaching in the terms of their functional contribution to accuracy. Elderly and young adults performed reaching movements to a visual target that could be displaced during reaching, and they were requested to move their hand to reach the final target location as quickly as possible. Results showed that, for the younger group, the variance in the directional error of the corrective response correlated with the variance in the reaching trajectory at the halfway point of the reach, but the correlation decreased at the end of the reaching. On the other hand, such correlations were not significant in elderly participants, although the variance of the directional error did not show a significant difference between age groups. Thus, the quick, corrective response seems to play an important role in decreasing variability, especially before the end of reaching, and aging can impair this process.

No MeSH data available.