Faculty Collaboration Database

Contribution of implicit memory to adaptation of movement extent during reaching against unpredictable spring-like loads: insensitivity to intentional suppression of kinematic performance. Exp Brain Res 2023 Sep;241(9):2209-2227

Date

07/29/2023

Pubmed ID

37507633

DOI

10.1007/s00221-023-06664-z

Scopus ID

2-s2.0-85165963276 (requires institutional sign-in at Scopus site)

Abstract

We examined the extent to which intentionally underperforming a goal-directed reaching task impacts how memories of recent performance contribute to sensorimotor adaptation. Healthy human subjects performed computerized cognition testing and an assessment of sensorimotor adaptation, wherein they grasped the handle of a horizontal planar robot while making goal-directed out-and-back reaching movements. The robot exerted forces that resisted hand motion with a spring-like load that changed unpredictably between movements. The robotic test assessed how implicit and explicit memories of sensorimotor performance contribute to the compensation for the unpredictable changes in the hand-held load. After each movement, subjects were to recall and report how far the hand moved on the previous trial (peak extent of the out-and-back movement). Subjects performed the tests under two counter-balanced conditions: one where they performed with their best effort, and one where they intentionally sabotaged (i.e., suppressed) kinematic performance. Results from the computerized cognition tests confirmed that subjects understood and complied with task instructions. When suppressing performance during the robotic assessment, subjects demonstrated marked changes in reach precision, time to capture the target, and reaction time. We fit a set of limited memory models to the data to identify how subjects used implicit and explicit memories of recent performance to compensate for the changing loads. In both sessions, subjects used implicit, but not explicit, memories from the most recent trial to adapt reaches to unpredictable spring-like loads. Subjects did not "give up" on large errors, nor did they discount small errors deemed "good enough". Although subjects clearly suppressed kinematic performance (response timing, movement variability, and self-reporting of reach error), the relative contributions of sensorimotor memories to trial-by-trial variations in task performance did not differ significantly between the two testing conditions. We conclude that intentional performance suppression had minimal impact on how implicit sensorimotor memories contribute to adaptation of unpredictable mechanical loads applied to the hand.

Author List

Lantagne DD, Mrotek LA, Hoelzle JB, Thomas DG, Scheidt RA

Authors

Robert Scheidt BS,MS,PhD Associate Professor in the Biomedical Engineering department at Marquette University
Danny G. Thomas MD, MPH Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adaptation, Physiological
Biomechanical Phenomena
Humans
Memory
Movement
Psychomotor Performance