Time-dependent influence of sensorimotor set on automatic responses in perturbed stance

Area of Science:

• Neuroscience
• Motor Control
• Human Movement Science

Background:

• Sensorimotor set influences the sensorimotor system's state based on prior experience.
• Automatic postural responses are crucial for maintaining balance.
• Understanding sensorimotor set adaptation is key to explaining motor learning and adaptation.

Purpose of the Study:

• To test if the time interval between successive surface perturbations affects the speed of sensorimotor set change for automatic responses.
• To investigate the lingering effects of sensorimotor set on postural control.
• To determine how inter-trial intervals impact the suppression of antagonist muscle responses.

Main Methods:

• Young, healthy subjects performed postural response tasks involving support surface translations and rotations.
• Two groups were studied: one with short (10-14s) and one with long (19-24s) inter-trial intervals.
• Gastrocnemius muscle responses and surface plantarflexor torque were measured to infer sensorimotor set changes.

Main Results:

• Longer inter-trial intervals facilitated immediate suppression of gastrocnemius responses to new perturbations.
• Short inter-trial intervals delayed the suppression of gastrocnemius responses, requiring multiple trials for adaptation.
• When perturbations alternated, the short-interval group showed less suppression compared to the long-interval group.

Conclusions:

• The ability to rapidly change sensorimotor set is sensitive to the time interval between successive trials.
• Close succession of different perturbations makes sensorimotor set harder to adjust, appearing as increased set strength.
• Findings suggest inter-trial time intervals play a significant role in sensorimotor adaptation rates.