Dexterity over a Lifespan

  • Upper/Lower Extremity Control

    Dexterity, defined as the dynamic control of forces to interact with the environment, improves in typically developing children with practice and neuromaturation. At the other extreme of the lifespan, there is a decline in dexterity with aging related to deterioration of brain function, sensory acuity, and muscle function. This has been shown in both the upper and lower extremities in previous research in the literature (including from our group). To date, the dynamical control of the upper and lower extremities has not been explored simultaneously. We aim to investigate the relationship between rates of development and decline of dynamical control in both the upper and lower extremities; and quantify potential age-related effects on this relationship.This study investigates the potential relationships between the abilities of the upper and lower extremities when stabilizing interactions with objects and the environment. The presence or lack of synchrony in the maturation and/or decline in these two modes of dexterity throughout the lifespan will be informative of the way the nervous system adapts to produce dynamic function in these two different, but interrelated limb systems (hand vs. leg). By testing across the lifespan, it also aims to better understand the influence of sensorimotor noise, cortical sensory and motor information processing, differential strengthening and weakening of muscles across these limb systems, and time delays in both development and aging.We propose to collect data from 200 subjects (100 male, 100 female) between the ages of 10 and 100. Subjects will be asked to compress springs with given stiffness and stability properties with the upper and lower extremities. As in our prior published studies, these springs will be hand held (upper extremity) and ground-mounted (lower extremity). Joint positions, spring motion, and spring forces will be analyzed to determine movement strategies. We will record electromyographic (EMG) activity of the muscles in the hand and leg to look at how the muscles contribute to performance. We will also assess reflex function by recording H-reflex, a well-established neurological technique uses mild stimulation though the skin, well below the threshold of pain, while recording EMG. Sensorimotor integration will be evaluated by upper and lower extremity dexterity tests. The performance on the behavioral measures will be compared between males and females, upper and lower extremities, and across a lifespan. Traditional analysis measures such as T-tests, Principal Components Analysis (PCA), and linear regression, among other techniques will be used to analyze the data from this study.

    For more information, contact:
    Emily Lawrence
    Study Coordinator
    ellawren@usc.edu

     Quantification of Dexterous Manipulation

    This study is about how people use their fingers to handle objects. We would like to learn how to measure how well the brain coordinates with the action of multiple fingers. 

    You may be eligible if you:

    • Are over the age of 4 years
    • Have normal or corrected vision
    • Have no history of neurological disorders, hand injury or disease, or repetitive stress injuries.

    If you agree to participate, the testing will take no more than one hour. We will take measurements of your hands, including finger and pinch strength. We will ask you to squeeze and hold springs with your hands.

    For more information, contact:
    Na-hyeon Ko
    Study Contact Person
    nko@usc.edu

    HS protocol # HS-08-00414
    Grant #: EFRI-COPN 0836042, NIH Grants AR050520 & AR052345, 84-133E2008-8
    Sponsor: National Science Foundation, National Institute of Health, National Institute on Disability and Rehabilitation Research