Plan-based generalization shapes local implicit adaptation to opposing visuomotor transformations.

Area of Science:

• Motor control and learning
• Cognitive neuroscience
• Human-computer interaction

Background:

• Humans possess the remarkable ability to form and maintain multiple, context-specific motor memories, crucial for tool use.
• Dual adaptation paradigms investigate this by having participants adapt reaching movements to opposing visuomotor transformations.
• Adaptation may involve distinct strategies or implicit acquisition of separate visuomotor mappings, with aftereffects often interpreted as evidence for the latter.

Purpose of the Study:

• To investigate the generalization of explicit and implicit adaptation to untrained movement directions.
• To determine if contextual cues, like visual workspace separation, enable dual adaptation of opposing visuomotor transformations.
• To disentangle whether distinct processes or local adjustments of a single map underlie dual adaptation.

Main Methods:

• Participants practiced two opposing cursor rotations associated with visual display halves (left/right).
• Explicit and implicit adaptation generalization to untrained directions were assessed.
• Target arrangements and instructions were varied to analyze generalization patterns.

Main Results:

• Participants developed explicit aiming strategies specific to the visual workspace cue for compensating rotations.
• Aftereffects were not sensitive to the workspace cue, suggesting implicit learning was independent of it.
• Aftereffects showed bimodal generalization, indicating locally limited learning around movement plans for both transformations.

Conclusions:

• Contextual cues like visual workspace separation enable dual visuomotor adaptation through explicit and implicit processes.
• Explicit strategies are context-dependent, while implicit visuomotor maps support dual adaptation independently of arbitrary cues.
• Implicit adaptation generalizes locally around explicit movement plans, demonstrating a complex interaction between strategies and learning.