Why do we remember some events, places and things, but not others?
"Rewards help you remember things, because you want future rewards," said Professor Charan Ranganath, a UC Davis neuroscientist and senior author on the paper. "The brain prioritizes memories that are going to be useful for future decisions."
Ranganath and postdoctoral researcher Matthias Gruber put this to the test by scanning the brains of volunteers by functional magnetic resonance imaging as they answered simple yes-no questions on short series of objects -- for example, "do these objects weigh more than a basketball?" Each series of objects was shown on a background image for context, and depending on the context, the volunteers were told they would either get a large (dollars) or small (cents) reward for giving correct answers. At the end of a series, participants were told how much money they just won.
Once participants completed this part of the experiment, the volunteers were scanned during a resting period. Afterward, outside of the scanner, there was a surprise memory test for all objects that were shown during scanning.
Although participants were not expecting the memory test outside the scanner, they were better at remembering objects that were associated with a high reward, said Gruber, first author of the paper.
Memory could be biased toward high points of experience.
Although this study did not measure it directly, these interactions were likely related to release of dopamine, a neurotransmitter that is released in the brain when we expect rewards. Conditions such as Parkinson's disease or aging are linked to reduced dopamine and often involve memory defects.
Source material from University of California - Davis