Investigating premotor reaching biases after prism adaptation

Area of Science:

• Neuroscience
• Cognitive Psychology
• Rehabilitation Science

Background:

• Prism adaptation (PA) is a visuomotor learning task with therapeutic potential for post-stroke spatial neglect.
• Individual variability in PA treatment benefits may relate to neglect subtypes: perceptual (input) versus premotor (output).
• Previous research suggests PA primarily benefits individuals with premotor neglect.

Purpose of the Study:

• To investigate if PA modulates the premotor stage of information processing.
• To determine if PA can induce a premotor bias in healthy adults.

Main Methods:

• A speeded reach task was used to measure perceptual and premotor biases before and after PA.
• Participants initiated leftward and rightward reaches to lateralized targets from varying hand start positions.
• Thirty healthy adults underwent either left-shifting or right-shifting PA in a randomized mixed design.

Main Results:

• Left-shifting PA significantly speeded the initiation time for rightward reaches (p=.02, η²=.18).
• This effect occurred regardless of target location, indicating a direction-specific premotor bias.
• The findings support the hypothesis that PA induces a premotor bias aligned with the prism aftereffect direction.

Conclusions:

• PA appears to induce a bias at the premotor stage of visuomotor processing.
• These findings contribute to understanding PA's mechanisms in visuomotor learning.
• The results have implications for optimizing PA as a treatment for spatial neglect.