title: Rapid Visuomotor Corrective Responses during Transport of Hand-Held Objects Incorporate Novel Object Dynamics.
abstract: Numerous studies have shown that people are adept at learning novel object dynamics, linking applied force and motion, when performing reaching movements with hand-held objects. Here we investigated whether the control of rapid corrective arm responses, elicited in response to visual perturbations, has access to such newly acquired knowledge of object dynamics. Participants first learned to make reaching movements while grasping an object subjected to complex load forces that depended on the distance and angle of the hand from the start position. During a subsequent test phase, we examined grip and load force coordination during corrective arm movements elicited (within ∼150 ms) in response to viewed sudden lateral shifts (1.5 cm) in target or object position. We hypothesized that, if knowledge of object dynamics is incorporated in the control of the corrective responses, grip force changes would anticipate the unusual load force changes associated with the corrective arm movements so as to support grasp stability. Indeed, we found that the participants generated grip force adjustments tightly coupled, both spatially and temporally, to the load force changes associated with the arm movement corrections. We submit that recently learned novel object dynamics are effectively integrated into sensorimotor control policies that support rapid visually driven arm corrective actions during transport of hand held objects. Significance statement: Previous studies have demonstrated that the motor system can learn, and make use of, internal models of object dynamics to generate feedforward motor commands. However, it is not known whether such internal models are incorporated into rapid, automatic arm movement corrections that compensate for errors that arise during movement. Here we demonstrate, for the first time, that internal models of novel object dynamics are integrated into rapid corrective arm movements made in response to visuomotor perturbations that, importantly, do not directly perturb the object.
authors.affiliation: Centre for Neuroscience Studies and.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Diamond
authors.affiliation: Centre for Neuroscience Studies and.
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Nashed
authors.affiliation: Department of Integrative Medical Biology, Physiology Section, Umeå University, SE-901 87 Umeå, Sweden, and.
authors.forename: Roland S
authors.identifier: http://orcid.org/0000-0003-3288-8326
authors.initials: RS
authors.lastname: Johansson
authors.affiliation: Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, United Kingdom.
authors.forename: Daniel M
authors.identifier: http://orcid.org/0000-0003-2011-2790
authors.initials: DM
authors.lastname: Wolpert
authors.affiliation: Centre for Neuroscience Studies and Department of Psychology, Queen's University, Kingston, Ontario K7L 3N6, Canada, flanagan@queensu.ca.
authors.forename: J Randall
authors.identifier: http://orcid.org/0000-0003-2760-6005
authors.initials: JR
authors.lastname: Flanagan
mesh_terms: D000328:Adult; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D055815:Young Adult
keywords: internal model; motor learning; object manipulation; reaching; visuomotor control