Startle reduces recall of a recently learned internal model

Area of Science:

• Neuroscience
• Motor Control
• Motor Learning

Background:

• Preplanned motor programs can be released early by a startling acoustic stimulus (SAS).
• It remains unclear if these early releases incorporate recently learned internal models for feedforward compensation.
• Previous studies using robotic forces were potentially confounded by cocontraction due to startle.

Purpose of the Study:

• To investigate whether a startling acoustic stimulus (SAS) releases motor programs containing recently learned internal models.
• To examine the effect of SAS on motor adaptation without confounding factors like cocontraction.

Main Methods:

• An adaptation experiment was conducted using a visually distorted field to avoid cocontraction.
• Subjects performed a recently learned task under normal and startling acoustic stimulus (SAS) conditions.
• Performance and after-effect magnitudes were measured to assess the impact of SAS.

Main Results:

• The startling acoustic stimulus (SAS) reduced performance in the recently learned task for all subjects exhibiting startle.
• SAS also reduced the magnitude of after-effects associated with the learned motor control.
• Learned control recall was reduced but not eliminated by the SAS.

Conclusions:

• The findings suggest that motor learning and adaptation involve multiple neural centers, including both cortical and subcortical areas.
• Startling acoustic stimulus (SAS) impacts the recall of learned motor control, but does not abolish it.
• These insights have implications for training in fields such as piloting, teleoperation, sports, and rehabilitation.