title: Effect of blocking tactile information from the fingertips on adaptation and execution of grip forces to friction at the grasping surface.
abstract: Adaptation of fingertip forces to friction at the grasping surface is necessary to prevent use of inadequate or excessive grip forces. In the current study we investigated the effect of blocking tactile information from the fingertips noninvasively on the adaptation and efficiency of grip forces to surface friction during precision grasp. Ten neurologically intact subjects grasped and lifted an instrumented grip device with 18 different frictional surfaces under three conditions: with bare hands or with a thin layer of plastic (Tegaderm) or an additional layer of foam affixed to the fingertips. The coefficient of friction at the finger-object interface of each surface was obtained for each subject with bare hands and Tegaderm by measuring the slip ratio (grip force/load force) at the moment of slip. We found that the foam layer reduced sensibility for two-point discrimination and pressure sensitivity at the fingertips, but Tegaderm did not. However, Tegaderm reduced static, but not dynamic, tactile discrimination. Adaptation of fingertip grip forces to surface friction measured by the rate of change of peak grip force, and grip force efficiency measured by the grip-load force ratio at lift, showed a proportional relationship with bare hands but were impaired with Tegaderm and foam. Activation of muscles engaged in precision grip also varied with the frictional surface with bare hands but not with Tegaderm and foam. The results suggest that sensitivity for static tactile discrimination is necessary for feedforward and feedback control of grip forces and for adaptive modulation of muscle activity during precision grasp.
authors.affiliation: Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York;
authors.forename: Seda
authors.initials: S
authors.lastname: Bilaloglu
authors.affiliation: Center for the Promotion of Research Involving Innovative Statistical Methodology, Steinhardt School of Culture, Education and Human Development, New York University, New York, New York;
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York;
authors.forename: Daniel
authors.initials: D
authors.lastname: Geller
authors.affiliation: Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York;
authors.forename: John Ross
authors.initials: JR
authors.lastname: Rizzo
authors.affiliation: Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York;
authors.forename: Viswanath
authors.initials: V
authors.lastname: Aluru
authors.affiliation: Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York; and.
authors.forename: Esther P
authors.initials: EP
authors.lastname: Gardner
authors.affiliation: Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York; Department of Physical Therapy, Steinhardt School of Culture, Education and Human Development, New York University, New York, New York preeti.raghavan@nyumc.org.
authors.forename: Preeti
authors.initials: P
authors.lastname: Raghavan
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D004192:Discrimination, Psychological; D025461:Feedback, Physiological; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D018737:Hand Strength; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D011930:Reaction Time; D013499:Surface Properties; D014110:Touch; D055698:Touch Perception
keywords: electromyography; feedforward and feedback control; precision grasp; sensorimotor adaptation; tactile perception