Summary: When thinking about the future is more helpful, people rely on memories of past experiences to make choices.
Replaying past experiences when learning something new can improve the brain’s ability to make future plans and preserve memories of the past, according to new research from UCL neuroscientists.
The study, published in PNASused brain imaging techniques to detect activity in the brains of 24 participants while taking part in a maze task.
As part of the experiment, participants were asked to make a series of choices between shapes in order to achieve rewards.
Each shape would lead down a different path consisting of a sequence of images, followed by reward points at the end. The participants’ goal was to keep track of the best path, as the reward points at the end changed over time.
The results showed that when thinking about the future was most helpful, participants replayed memories of past experiences before making a choice.
The researchers also looked at participants’ brain activity during a brief break after receiving feedback. Here, they found that participants increasingly thought about the less traveled paths of the maze, indicating that a memory was being preserved.
Interestingly, replay events were very fast – completing a path in a fraction of a second.
The results demonstrate how replaying experiences at different times can be linked to two distinct cognitive functions. However, both effects were linked to increased activity in regions of the brain, including the hippocampus, which is crucial for memory.
Lead author Dr Elliott Wimmer (UCL Queen Square Institute of Neurology and The Max Planck UCL Center for Computational Psychiatry and Aging Research) said: “Our research found that proofreading can help both key mental abilities , decision-making and memory, but at different times.
“When it’s time to make a decision, replay focusing on the task at hand, supporting the role of memory in planning. But during more inactive periods, replaying was stronger for previous memories, which can help maintain old experiences.
The team now hope the findings will help future research into conditions such as mood disorders and dementia.
Dr Wimmer said: “The brain can prioritize one function over the other depending on the situation. By finding two distinct functions of proofreading, these results could guide future research on decision-making and memory problems in psychiatric and memory disorders.
Funding: The research was funded by Wellcome and the Max Planck Society.
About this research news on decision-making and memory
Author: Danby Poppy
Contact: Danby Poppy – UCL
Picture: Image is in public domain
Original research: Free access.
“Distinct proofreading signatures for forward-looking decision-making and memory preservation” by Elliott Wimmer et al. PNAS
Distinct replay signatures for forward-looking decision-making and memory preservation
Neural proofreading theories propose that it supports a range of functions, primarily planning and memory consolidation.
Here, we test the hypothesis that distinct proofreading signatures in the same task are related to model-based decision-making (“planning”) and memory preservation.
We designed a reward-learning task in which participants used knowledge of the structure for model-based assessment, while having to maintain knowledge of two independent, randomly alternating task environments.
Using magnetoencephalography and multivariate analysis, we first identified time-compressed sequential reactivation, or replay, both before choice and after reward feedback. Prior to choice, prospective replay strength was improved for the current task-relevant environment when a model-based planning strategy was beneficial.
Following receipt of the reward, and consistent with a memory-preserving role, replaying for the alternate distal task environment was enhanced based on the decrease in recency of experience with that environment. Critically, these planning and memory preservation relationships were selective for the pre-choice and post-feedback periods, respectively.
Our results support key theoretical propositions regarding the functional role of proofreading and demonstrate that the relative strength of planning and memory-related cues are modulated by ongoing computational and task demands.