Memory helps us to evaluate situations on the fly, not just to remember the past


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Scientists know that the hippocampus of the brain is crucial for long-term memory. Now, a new Northwestern medical study has found that the hippocampus also plays an important role in short-term memory and helps guide decision-making.

The findings shed light on how the hippocampus contributes to memory and exploration, which can lead to therapies that restore hippocampal function, which is affected by memory-related aging and neurodegenerative diseases such as dementia, according to the study authors.

In the study, scientists monitored participants ’brain activity and tracked eye movements while observing different complex images. Scientists found that as we visually scan our environment and absorb new information, our hippocampus is activated, using short-term memory to better process new visual information to help us quickly assess situations.

How our memory helps us scan new environments

Imagine walking down the street and noticing an awkward car parked on your neighbor’s lawn. Maybe you say goodbye quickly and move on. But when you see an ambulance and a fire truck approaching your location, connect the dots and look back to see the scene of an accident. By using short-term memory to guide where you look, the hippocampus allows you to reexamine the car and form a lasting memory of the accident.

A short explanatory video describes how the scientists tracked eye movement and analyzed the electrical activity of the brain in the study. Credit: Kristin Samuelson / Northwestern University

“At some point, the brain quickly initiates eye movements that you would normally be unaware of,” said corresponding author James Kragel, a postdoctoral researcher at Northwestern University’s Feinberg School of Medicine. “Our findings suggest that the hippocampus uses memory to inform where your eyes are looking, thus preparing the visual system to learn and reevaluate our environment on the fly.

“If you didn’t look back and see the lock, you may not encode this important information, but use recovery, you can link these tracks and remember details that indicate larger memories. It’s all about building connections between these disparate elements that allow you to remember them later in a much simpler way. “

The study will be published in the journal on June 18 Scientific advances.

“These findings emphasize that while hippocampal-dependent memory is usually considered a thing of the past, in fact, it operates at the time to optimize our behavior and our decision-making,” said Joel Voss, author principal of the study, associate professor of medical social sciences, neurology and psychiatry, and behavioral sciences at Feinberg. “This is key to understanding hippocampal function and developing effective treatments for memory disorders.”

“It’s like you’re using your memory to plan what you can expect, and when it doesn’t match what’s really developing, your hippocampus is activated to re-evaluate and update your current perception of what’s going on,” he said. Kragel.

Track eye movements for more information on memory

The study was performed on patients with epilepsy who were undergoing neurosurgical control at Northwestern Memorial Hospital to locate the source of their seizures. They had electrodes implanted in the brain to map seizure-related brain activity. During their stay in the epilepsy control unit, participants performed a memory task in which they studied lists of complex scenes with various people and objects (for example, someone sitting on a park bench with food in the table, things happening in the background). a memory test.

During the test, participants indicated whether a scene presented was old or new. Throughout the task, the authors simultaneously recorded eye movements and neuronal activity to link hippocampal activity with memory-guided behaviors.

When they first studied a scene, participants often turned their gaze to a place they had just seen hundreds of milliseconds before. This “revisitation” improved spatiotemporal memory for scenes (remembering where an object was or the sequence in which something happened). Brain recordings revealed the networks involved in the generation of these “revisitations,” as hippocampal activity was changed just prior to their execution. Increases in followed by revisitations, which Kragel believes may form a lasting memory of the scene and its elements.

“This shows that the contribution of the hippocampus to it develops over only hundreds of milliseconds during continuous behavior, which is surprising considering the time course of its participation, recovery is usually believed to be from day to year, ”Voss said.

Navigating the squirrel: Hippocampal maps predict context-dependent behavior

More information:
JE Kragel et al., “Rapid coordination of effective learning by the human hippocampus.” Scientific advances (2021). …. .1126 / sciadv.abf7144

Citation: Memory helps us assess situations on the fly, not just remember the past (2021, June 18) retrieved June 18, 2021 at -recall.html

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