Human brain keeps memories tidy by pruning inaccurate ones
by Michael Hotchkiss
Forget about it. Your brain is a memory powerhouse, constantly recording experiences in long-term memory. Those memories help you find your way through the world: Who works the counter each morning at your favorite coffee shop? How do you turn on the headlights of your car? What color is your best friend's house?
But then your barista leaves for law school, you finally buy a new car and your buddy spends the summer with a paint brush in hand. Suddenly, your memories are out of date.
What happens next?
An experiment conducted by researchers from Princeton University and the University of Texas-Austin shows that the human brain uses memories to make predictions about what it expects to find in familiar contexts. When those subconscious predictions are shown to be wrong, the related memories are weakened and are more likely to be forgotten. And the greater the error, the more likely you are to forget the
memory.
"This has the benefit ultimately of reducing or eliminating noisy or inaccurate memories and prioritizing those things that are more reliable and that are more accurate in terms of the current state of the world," said Nicholas Turk-Browne, an associate professor of psychology at Princeton and one of the researchers. he research was featured in an article, "Pruning of memories by context-based prediction error," that appeared in 2014 in the
Proceedings of the National Academy of Sciences. The other co-authors are Ghootae Kim, a Princeton graduate student; Jarrod Lewis-Peacock, an assistant professor of psychology at the University of Texas-Austin; and Kenneth Norman, a Princeton professor of psychology and the Princeton Neuroscience Institute.
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The researchers' experiment involved 24 adults, who were shown a series of photos one at a time while their
brain activity was monitored by a functional magnetic resonance imaging (fMRI) machine. The participants were asked a question about each photo, but the real purpose of the exercise was to monitor their brain activity as the photos were shown.
The photos included three-photo sequences, such as two photos of faces followed by a photo of a scene. In this example, the first two photos would appear again later in the series, but this time would be followed by a new face rather than the scene. The researchers measured how strongly participants were expecting to see a photo of the scene the second time by looking for the pattern of brain activity associated with that scene, around the time when it should have appeared in the sequence. Read more at:
http://medicalxpress.com/news/2015-01-human-brain-memories-tidy-pruning.html