How our brain makes predictions everyday
Washington: Almost everyday we all make certain predictions like who is knocking the door, when will the bus arrive and so on. Now, for the very first time, the researchers at Washington University in St. Louis have begun to unravel the process by which the brain makes these everyday prognostications.
The researchers focused on the mid-brain dopamine system (MDS), an evolutionarily ancient system that provides signals to the rest of the brain when unexpected events occur. Using functional MRI (fMRI), they found that this system encodes prediction error when viewers are forced to choose what will happen next in a video of an everyday event.
Predicting the near future is vital in guiding behaviour and is a key component of theories of perception, language processing and learning, said Jeffrey M. Zacks, PhD, WUSTL associate professor of psychology in Arts and Sciences and lead author of a paper.
Zacks tested healthy young volunteers who were shown movies of everyday events such as washing a car, building a LEGO model or washing clothes. The movie would be watched for a while, and then it was stopped.
Participants then were asked to predict what would happen five seconds later when the movie was re-started by selecting a picture that showed what would happen, and avoiding similar pictures that did not correspond to what would happen.
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.
In the functional MRI experiment, Zacks and his colleagues saw significant activity in several midbrain regions, among them the substantia nigra — "ground zero for the dopamine signaling system" — and in a set of nuclei called the striatum.
Mid-brain responses “really light up at hard times, like crossing the event boundary and when the subjects were told that they had made the wrong choice,” Zacks said.
The study is detailed in forthcoming issue of the Journal of Cognitive Neuroscience.