Sensory prediction errors, not performance errors, update memories in visuomotor adaptation

Kangwoo Lee,Jun Izawa,Nicolas Schweighofer,Youngmin Oh

doi:10.1038/s41598-018-34598-y

Kangwoo Lee, Jun Izawa + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-34598-y

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Abstract

Sensory prediction errors are thought to update memories in motor adaptation, but the role of performance errors is largely unknown. To dissociate these errors, we manipulated visual feedback during fast shooting movements under visuomotor rotation. Participants were instructed to strategically correct for performance errors by shooting to a neighboring target in one of four conditions: following the movement onset, the main target, the neighboring target, both targets, or none of the targets disappeared. Participants in all conditions experienced a drift away from the main target following the strategy. In conditions where the main target was shown, participants often tried to minimize performance errors caused by the drift by generating corrective movements. However, despite differences in performance during adaptation between conditions, memory decay in a delayed washout block was indistinguishable between conditions. Our results thus suggest that, in visuomotor adaptation, sensory predictions errors, but not performance errors, update the slow, temporally stable, component of motor memory.

Highlights

What is the mechanism that enables adaptation in response to a sensory perturbation? A long-held theoretical view is that sensory-motor adaptation is due to the update of internal forward models[1,2], which are neural processes that predict the sensory consequences of motor commands[3,4,5]
When PE1 was present, participants often attempted to compensate for the drift by generating corrections to reduce the performance error between the main target and the cursor
We manipulated the availability of performance errors following fast shooting movements in a visuomotor adaptation experiment in which participants were instructed to correct the given perturbation by strategically shooting to a neighboring target

Summary

Introduction

What is the mechanism that enables adaptation in response to a sensory perturbation? A long-held theoretical view is that sensory-motor adaptation is due to the update of internal forward models[1,2], which are neural processes that predict the sensory consequences of motor commands[3,4,5]. This is because just after the strategy is introduced, the drift appears despite zero performance error This experiment did not allow for a disambiguation of the roles of SPEs versus performance errors on updating motor memories, because both types of errors were present in the drift phase. An extension of this initial study by Taylor and Ivry[16] with a larger number of adaptation trials showed that the performance error between the cursor and the main target that appears during the drift phase influences performance during adaptation: when the number of trials increased, participants started to generate corrective movements to cancel the drift. We call the second type of performance error, the error between the neighboring target and the cursor, PE2 (See Fig. 1A)

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