Recent work has shown that preplanned motor programs can
be rapidly released via fast conducting pathways using a startling acoustic
stimulus. Our question was whether the startle-elicited response might also
release a recently learned internal model, which draws on experience to predict
and compensate for expected perturbations in a feedforward manner. Our initial
investigation using adaptation to robotically produced forces showed some
evidence of this, but the results were potentially confounded by co-contraction
caused by startle. In this study, we eliminated this confound by asking
subjects to make reaching movements in the presence of a visual distortion.
Results show that a startle stimulus (1) decreased performance of the recently
learned task and (2) reduced after-effect magnitude. Since the recall of
learned control was reduced, but not eliminated during startle trials, we
suggest that multiple neural centers (cortical and subcortical) are involved in
such learning and adaptation. These findings have implications for motor
training in areas such as piloting, teleoperation, sports, and rehabilitation.
Website for this document