Startle stimuli reduce the internal model control in discrete movements.
A well known and major component of movement control is the feedforward component, also known as the internal model. This model predicts and compensates for expected forces seen during a movement, based on recent experience, so that a well-learned task such as reaching to a target can be executed in a smooth straight manner. It has recently been shown that the state of preparation of planned movements can be tested using a startling acoustic stimulus (SAS). SAS, presented 500, 250 or 0 ms before the expected "go" cue resulted in the early release of the movement trajectory associated with the after-effects of the force field training (i.e. the internal model). In a typical motor adaptation experiment with a robot-applied force field, we tested if a SAS stimulus influences the size of after-effects that are typically seen. We found that in all subjects the after-effect magnitudes were significantly reduced when movements were released by SAS, although this effect was not further modulated by the timing of SAS. Reduced after-effects reveal at least partial existence of learned preparatory control, and identify startle effects that could influence performance in tasks such as piloting, teleoperation, and sports.
Wright
Zachary A
ZA
University of Illinois at Chicago, Illinois 60607, USA.
Rogers
Mark W
MW
MacKinnon
Colum D
CD
Patton
James L
JL
D000704:Analysis of Variance; D006801:Humans; D007858:Learning / Q000502:physiology*; D008962:Models, Theoretical; D009068:Movement / Q000502:physiology*; D010865:Pilot Projects; D013216:Reflex, Startle / Q000502:physiology*; D012371:Robotics / Q000379:methods*; D055815:Young Adult