How do our brains remember everyday scenes?

Although previous studies have already investigated how our brain constructs memories, they tended to use very simple objects and scenarios in their experimental setups, largely ignoring the dynamics of more complex real-world situations. 

To address these shortcomings, a research team led by the Washington University in St. Louis (WUSTL) has used MRI scanners to examine the brains of participants watching short videos of scenes similar to what we usually experience in our everyday lives, such as people working in laptops in a café or shopping in a grocery store. Shortly after visualizing these mundane scenes, participants were asked to describe them as detailed as possible.

The analysis revealed that, in order to understand and remember a situation, different parts of the brain work together. For instance, neuronal networks in the front side of the temporal lobe – a brain area known to play a crucial role in memory – focused on the subjects while ignoring the surroundings. By contrast, the posterior medial network – involving the parietal lobe located towards the back of the brain – paid more attention to the environment in which the subjects were embedded. Then, the two networks sent information to the hippocampus, which combined the signals to create a coherent and integrated scene.

These findings suggest that our brains make “mental sketches” of people which can be easily transposed from one location to another, in a similar way that an animator can copy and paste characters from one scene to another. “It may not seem intuitive that your brain can create a sketch of a family member that it moves from place to place, but it’s very efficient,” said study lead author Zachariah Reagh, an assistant professor of Psychological and Brain Sciences at WUSTL.

The MRI scans also revealed that the subjects who could remember the visualized scenes more accurately later on employed the same neural patterns when recalling the scenes that they used while watching the clips. “The more you can bring those patterns back online while describing an event, the better your overall memory,” Reagh explained.

However, the researchers stress that many things can get in a way of accurately remember what we have seen and that even memories that seem extremely vivid may be misleading. “I tell my students that your memory is not a video camera. It doesn’t give you a perfect representation of what happened. Your brain is telling you a story,” Reagh concluded.

The study is published in the journal Nature Communications.

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By Andrei Ionescu, Earth.com Staff Writer

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