Many older adults face impaired hand motor function, apart from arthritis, that affects their ability to grasp and manipulate objects. These declining motor abilities impede the capacity to perform daily living skills or pursue hobbies. Recent research indicates that the control of fingertip forces for dexterous grasp depends upon sensory information, sensory-motor integrative processes, and memory. Dysfunctions of these systems in older adults are common and may contribute to impaired dexterity by altering the fingertip forces for grasp. However, little research has been directed along these lines. The long-term objectives of this project are to: 1) Determine mechanisms that contribute to impaired prehension in old age; and, 2) Identify ways to ameliorate the functional impact of those mechanisms. The present proposal addresses the first of these goals by examining the effects of aging on the fingertip forces used during grasp. Hypotheses focus on possible mechanisms for altered fingertip forces in old age. Feasible mechanisms include; diminished peripheral sensory signals, impaired sensory-motor integration, and exceedingly variable muscle forces within an individual. The fingertip forces that old and young adults use to grasp and manipulate objects will be recorded while they grip and manipulate instrumented test objects. The ability of older adults to use sensory information to control fingertip forces will be studied by examining motor responses to slips of a grasped object, by subjecting a grasped object to unexpected pulling loads, and by surreptitiously varying the weight and friction of a test object that is grasped and lifted. However, these experiments alone cannot determine if changes in force control are due to faulty peripheral sensory input or an impaired ability to use the sensory information. Therefore, the effects of mild-to-moderate anesthesia of the hand on fingertip force control will be studied in young adults by experimental compression of the median nerve. Other studies will address directly if older adults suffer from impaired sensory-motor integration in grasp force control by examining their ability to use explicit visual and tactile information about object weight and friction to scale their grip force commands. Finally, reports that motor output in older adults is highly variable prompts studies on the variability of grip forces during manipulation and pinch tasks.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG012557-03
Application #
2413340
Study Section
Special Emphasis Panel (ZRG4-GRM (01))
Project Start
1995-05-15
Project End
1999-04-30
Budget Start
1997-05-01
Budget End
1998-04-30
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Iowa
Department
Other Health Professions
Type
Schools of Arts and Sciences
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Quaney, Barbara M; Rotella, Diane L; Peterson, Clayton et al. (2003) Sensorimotor memory for fingertip forces: evidence for a task-independent motor memory. J Neurosci 23:1981-6
Cole, Kelly J; Steyers, Curtis M; Graybill, Edward K (2003) The effects of graded compression of the median nerve in the carpal canal on grip force. Exp Brain Res 148:150-7
Cole, Kelly J; Rotella, Diane L (2002) Old age impairs the use of arbitrary visual cues for predictive control of fingertip forces during grasp. Exp Brain Res 143:35-41
Cole, K J; Rotella, D L (2001) Old age affects fingertip forces when restraining an unpredictably loaded object. Exp Brain Res 136:535-42
Cole, K J; Rotella, D L; Harper, J G (1999) Mechanisms for age-related changes of fingertip forces during precision gripping and lifting in adults. J Neurosci 19:3238-47
Cole, K J; Rotella, D L; Harper, J G (1998) Tactile impairments cannot explain the effect of age on a grasp and lift task. Exp Brain Res 121:263-9