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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.


(A) Schematic drawing of the experimental setup. Participants were asked to reach toward a visual target presented at the center of a screen placed at a distance of 0.5 m in a darkened room. (B) The sequence of a visual stimulus in the rightward target displacement condition. Four possible target displacement directions were implemented: to the right, left, upward, or downward from the center (all distances 4.5 cm). In the control condition, the target remained at the central position.
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Figure 1: (A) Schematic drawing of the experimental setup. Participants were asked to reach toward a visual target presented at the center of a screen placed at a distance of 0.5 m in a darkened room. (B) The sequence of a visual stimulus in the rightward target displacement condition. Four possible target displacement directions were implemented: to the right, left, upward, or downward from the center (all distances 4.5 cm). In the control condition, the target remained at the central position.

Mentions: Figure 1A shows the experimental set-up. A rear projection screen (760 × 560 mm), on which the visual stimulus was back-projected by a DLP projector (Pro8500, ViewSonic), was placed at a distance of 50 cm from the participant’s eyes. Visual stimuli were generated using Matlab (Math Works, Natick, MA, USA) and Cogent Graphics (University College London, London, UK) on a Microsoft Windows (Seattle, WA, USA) operating system. A photodiode was attached to the bottom left corner of the screen to detect the actual stimulus start time at a temporal resolution of 2 kHz. Each participant sat in a quasi-darkened room, and placed his/her chin on a support to stabilize the head. Using the tip of the right index finger, he/she then pressed a button switch attached to the table placed in front of the participant. The switch was connected to the computer’s parallel port, and the button release indicated onset of the reaching movement. A reflective marker was placed near the distal interphalangeal joint of the right index finger. The right wrist and index finger joints were immobilized using a plastic splint to prevent finger shaking. The marker position was recorded with three cameras located 2.5 m above the floor, which were interfaced with a motion capture system (Oqus 300, Qualisys, Sweden) working at a sampling frequency of 500 Hz. The spatial resolution was less than 0.15 mm in the mediolateral (x), horizontal (y), and vertical (z) directions.


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)

(A) Schematic drawing of the experimental setup. Participants were asked to reach toward a visual target presented at the center of a screen placed at a distance of 0.5 m in a darkened room. (B) The sequence of a visual stimulus in the rightward target displacement condition. Four possible target displacement directions were implemented: to the right, left, upward, or downward from the center (all distances 4.5 cm). In the control condition, the target remained at the central position.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: (A) Schematic drawing of the experimental setup. Participants were asked to reach toward a visual target presented at the center of a screen placed at a distance of 0.5 m in a darkened room. (B) The sequence of a visual stimulus in the rightward target displacement condition. Four possible target displacement directions were implemented: to the right, left, upward, or downward from the center (all distances 4.5 cm). In the control condition, the target remained at the central position.
Mentions: Figure 1A shows the experimental set-up. A rear projection screen (760 × 560 mm), on which the visual stimulus was back-projected by a DLP projector (Pro8500, ViewSonic), was placed at a distance of 50 cm from the participant’s eyes. Visual stimuli were generated using Matlab (Math Works, Natick, MA, USA) and Cogent Graphics (University College London, London, UK) on a Microsoft Windows (Seattle, WA, USA) operating system. A photodiode was attached to the bottom left corner of the screen to detect the actual stimulus start time at a temporal resolution of 2 kHz. Each participant sat in a quasi-darkened room, and placed his/her chin on a support to stabilize the head. Using the tip of the right index finger, he/she then pressed a button switch attached to the table placed in front of the participant. The switch was connected to the computer’s parallel port, and the button release indicated onset of the reaching movement. A reflective marker was placed near the distal interphalangeal joint of the right index finger. The right wrist and index finger joints were immobilized using a plastic splint to prevent finger shaking. The marker position was recorded with three cameras located 2.5 m above the floor, which were interfaced with a motion capture system (Oqus 300, Qualisys, Sweden) working at a sampling frequency of 500 Hz. The spatial resolution was less than 0.15 mm in the mediolateral (x), horizontal (y), and vertical (z) directions.

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.