People subconsciously make thousands of tiny predictions each day, e.g., when a bus will arrive, who is knocking on the door or if a dropped glass will break。
Researchers at Washington University in St Louis focused on the mid-brain dopamine system (MDS)， which provides signals to the rest of the brain when unexpected events occur。
The scientists tested healthy young volunteers who were shown films of everyday events. And then it was stopped. Participants were then asked to predict what would happen five seconds later。
Half of the time, the movie was stopped just before an event boundary, when a new event was just about to start. The other half of the time, the film was stopped in the middle of an event。
The researchers found that participants were more than 90 percent correct in predicting activity within the event, but less than 80 percent correct in predicting across the event boundary. They were also less confident in their predictions。
Using functional MRI (FMRI)， researchers found that this system encodes prediction error when participants made prediction. And they saw significant activity in several mid-brain regions, among them the substantial nigra, which is the part of the brain most affected by Parkinson's disease, and is important for controlling movement and making adaptive decisions。
Lead researcher Jeffrey Zacks said: "Successful predictions are associated with the subjective experience of a smooth stream of consciousness. But a few times a minute, our predictions come out wrong and then we perceive a break in the stream of consciousness."
The research is published in the Journal of Cognitive Neuroscience。