The brain actively works to forget trivial information, two University of Toronto researchers report in a review paper published in the current issue of the journal Cell.
The scientists propose that the goal of memory is to guide and contribute to intelligent decision-making by holding onto only valuable information.
“It’s important that the brain forgets irrelevant details and instead focuses on the stuff that’s going to help make decisions in the real world,” co-author Blake Richards said,
To analyze the nature of memory, the team reviewed scientific literature on remembering, known as persistence, and newer research on forgetting, or transience.
A recent surge in research into brain mechanisms that promote transience shows that forgetting is just as important as remembering for our memory system.
“We find plenty of evidence from recent research that there are mechanisms that promote memory loss, and that these are distinct from those involved in storing information,” co-author Paul Frankland said.
One such mechanism is the weakening or elimination of synaptic connections between neurons in which memories are stored. Another process, supported by evidence from Frankland’s lab, is the generation of new neurons from stem cells. As these neurons integrate into the hippocampus, a component of the brain that is associated with memories, the new connections overwrite memories stored in hippocampal circuits, making them harder to access.
Richards, whose research applies artificial intelligence theories to understanding the brain, reviewed principles of learning from AI for insight. Using these principles, the team framed an argument that the relationship between forgetting and remembering in the brain allows us to make decisions based on valuable and updated memories, which it does in two ways.
First, forgetting allows us to adapt to new situations by deleting outdated and possibly misleading information that is no longer relevant as we maneuver through changing environments.
“If you’re trying to navigate the world and your brain is constantly bringing up multiple conflicting memories, that makes it harder for you to make an informed decision,” Richards said.
The second way forgetting supports decision-making is by allowing us to generalize past events to new ones. This principle is called regularization in AI, and it works by creating basic computer models that prioritize key information while eliminating specific details.
Memories in the brain work in a similar way. By remembering only the gist of an encounter as opposed to every minor detail, we create simple memories that are more effective for processing new experiences.
These mechanisms are also affected by the nature of our environment.
“One of the things that distinguishes an environment where you’re going to want to remember stuff versus an environment where you want to forget stuff is this question of how consistent the environment is and how likely things are to come back into your life,” Richards said.