How Our Brains Reconstruct Memories

When those who remember something from our past, we often experience the whole situation that resulted from this again. A new study shows how this phenomenon occurs in the brain.

The study, published in the journal Nature Communications , shows that when a person tries to recall some aspect of a past event, such as meeting someone the day before, the brain has a complete picture of that event. entire event can be reactivated, including additional information such as where he was at the time and what he was doing.

Recalling a past event allows us to be completely absorbed in the experience. “When we think back to an event from our past, we are able to completely  immerse ourselves in the experience,” explains Dr Aidan Hornor, of the Institute of Cognitive Neuroscience and lead supervisor of this study.

“We remember which room we were in, the music playing, the person we were talking to and what was said,” Horner said.

Memories are stored in different parts of the brain

Horner explains that when we experience something, the different aspects of this experience are represented in different parts of the brain. However, when we recall this event at a later time, we are able to remember all these different aspects as a whole.

The hippocampus is fundamental in the process of retrieving memories. The hippocampus produces the connection between all these different aspects in such a way that the whole event can be rehearsed in its entirety.

The research shows that the connections that are formed between the different aspects of the event ensure that all aspects can be brought to the surface at the same time.

For example, when we remember something that we once experienced, we are often able to bring out all kinds of details as well, such as what we were doing and where we were. This means that the entire event can be re-experienced in its entirety.

Using functional nuclear magnetic resonance imaging (fMRI), the researchers were able to show that the different aspects of an event are reflected by the activity in different parts of the brain when a person thinks about the event.

When the study participants were asked some questions about certain aspects of a past event, the activity in the hippocampus corresponded to the reactivation of other parts of the brain. This reactivation was consistent with the whole event that the mind was trying to stir up.

The role of the hippocampus in the formation of memories

Neil Burgess, one of the other supervisors of this study, explains that this study supports the computational model of how our memory is assumed to function. In this model, when we want to remember something that happened in the past, the hippocampus ensures that different forms of information are brought together to be depicted and visualized as one cohesive whole.

In addition, it provides an important perspective on our ability to remember things that happened and can help us understand where things go wrong in this process in people who suffer from Alzheimer’s or post-traumatic stress disorder.

Run the experiment

Twenty-six volunteers participated in this experiment. These volunteers were asked to imagine and memorize a series of ‘events’ related to different places, famous people and everyday objects.

They were then asked to remember all the details associated with this event while being told only one element of this event. For example, during one trial, they were asked to imagine a situation where they were in the kitchen with Barack Obama holding a hammer.

They were then asked to recall all the details using just one indicator. For example, the indicator in this case could be: where is Barack Obama, who and what was in the kitchen or what object was Obama holding in his hands.

When the volunteers were asked to recall various aspects of these events, the volunteers lay in an fMRI machine that scanned and measured their brain activity while answering the question.

The results of this scan showed that the different parts of the brain showed more activity when certain aspects of the event were codified. The hippocampus made the right connections between the different aspects of the events to form a complete memory.

In the case of the example above, activity in one part of the brain increased when the volunteers thought of Obama, when they thought of the kitchen, and when they thought of the hammer.

The study also found that when the subject was asked where Obama was, there was increased brain activity in the areas of the brain associated with Obama and the kitchen.

What was especially important was that brain activity also increased in the part connected to the hammer, despite the fact that it was not necessary to bring this information out at all.

The reactivation corresponding to the activity in the hippocampus suggests that the hippocampus is linked to the ability to remember the event in its entirety.

This is the first study to provide evidence on the process of memory formation in the human hippocampus. It is also the first study to link this data to the usual practice of remembering things that happened in the past.