Preparation and control of rapid voluntary movements

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Picture two very different but real life scenarios. In the first a policeman in a patrol car pulls over a suspected stolen vehicle. The officer draws his gun and walks over to the driver side of the stolen vehicle. As he approaches the driver a car that is driving behind the policeman "backfires". The officer discharges his weapon into the stolen vehicle injuring the suspect. Did the officer intentionally fire his gun at the suspect? In the second scenario an Olympic track and field 100m final is underway and the world record holder is "under starter's orders" after having false started once before. The starter pistol is fired and the athlete "explodes" out of the blocks for what most believe to be a good start. However, he has produced an increase in force that is recorded on the "starting blocks" 96 ms after the starter pistol fired. The International Association of Athletics Federation state that any athlete increasing force on the "blocks" before 100 ms has passed after the starter signal must have "jumped the gun". Therefore the athlete was disqualified. Did the athlete intentionally anticipate the start without waiting for the sound of the starter pistol? Are these two scenarios related and can the actions of both the policeman and the athlete be explained? It is clear that fast responses to everyday stimuli are required of people on a daily basis and these movements have long been thought to be controlled via information flow through higher brain centres (cortical loops). However, we have recently shown (along with others) that when the prepared response is ready to go the loud signal has the effect of startling the individual causing the entire response to be released, in some instances without the subject being aware that the response has occurred. We have observed reaction times to unanticipated startling stimuli as low as 65 ms. Our hypothesis is that a prepared response is pre-programmed and stored in lower (subcortical) brain structures. When the signal arrives the response is triggered early by the startling sound, bypassing cortical processing and resulting in short reaction times. The programme of research that I propose will investigate the processes responsible for such fast prepared actions and shed light on their preparation, storage and execution.