What children without memory teach us about remembering – 01/08/2024 – Balance

You leave the office thinking about the weekend. As he walks down the hallway, he sees a face that seems familiar, although he can’t remember where he knows that person.

You endure the discomfort of the first moments of the conversation by pretending that this void in your memory doesn’t exist. But when you observe the smile of the person you are talking to, something is triggered in your mind.

Your head fills with images, places and names from your youth.

You finally breathe, relieved to have recognized an old friend. Where just a few minutes ago there was a desert of memories, they have now become an ocean.

Difference between knowing and remembering

Knowing is not the same as remembering.

For example, we know what an orange is or what the word wake up early means, without remembering exactly when and where we acquired this information.

This type of knowledge is very useful because it would be difficult to remember, one by one, every day, that we have to wake up early just to know the meaning of that word.

What we experience is very different when we remember what we ate for breakfast or where we celebrated our last birthday.

Psychologists call this very intimate feeling of being able to relive specific events in our lives in detail the “sense of remembering.”

All the memories that we can express verbally are included in our explicit (or declarative) memory, which in turn is divided into two types.

On the one hand, there is the ability to relive events from our past in detail, known as episodic memory (what we remember).

And, on the other hand, general knowledge about the world, called semantic memory (what we know).

The role of the hippocampus in remembering

In a study using magnetoencephalography, we were able to record the brain rhythms of healthy people while they performed a memory task.

We observed that the alpha rhythm (about 12 hertz) changed more strongly when people were able to remember the details associated with the event than when they simply knew they had seen the stimulus before.

When we observed in which regions of the brain this effect occurred, we observed that the hippocampus only came into action if the person was able to remember the entire episode.

Although the hippocampus is part of a broad network of brain circuits that are activated during memory, it is an essential structure for the functioning of episodic memory.

In fact, adults who suffer damage to the hippocampus develop anterograde amnesia and lose the ability to create new episodic memories.

Fortunately, these patients keep their ability to use semantic memory intact: they have no language problems and can perfectly identify objects in their environment.

Children who know but don’t remember

Is it essential to create episodic memories to generate general knowledge about the world?

Intuitively we think that it is necessary to record several experiences with dogs to generate the concept of “dog”.

The case of adults with anterograde amnesia does not allow us to easily answer this question, as they generated their semantic memory before the injury.

But what happens if a child suffers this type of injury shortly after birth?

At first glance, she would be a child with no memories of her personal past.

Could you learn the meaning of words or recognize objects?

Psychologist Faraneh Vargha-Khadem and her collaborators have been studying cases of developmental amnesia caused by early damage to the hippocampus for years.

The first cases studied were three children named Beth, Jon and Kate.

Just like adults, they couldn’t remember the last TV show they watched or what they got for their birthday.

Despite this difficulty, they seemed to have acquired semantic knowledge without any problems.

Surprisingly, these children acquired vocabulary, went to school and interacted with the environment without being able to remember where they were the day before.

Vargha-Khadem shares an anecdote with patient Jon that highlights this difference between remembering and knowing.

Jon always took the same route to go to his laboratory in London: he took the subway at a nearby station and when he reached his destination, he took the elevator to the surface.

However, that day the elevator broke down and he had to climb several flights of stairs. When he arrived at the laboratory he didn’t remember anything about what happened and said he had gone up in the elevator.

When asked “How do you know you used the elevator today?” he replied, “I always take the elevator.”

In other words, faced with the impossibility of remembering what had happened, he used his semantic knowledge to answer the question.

These data indicate that knowing and remembering are two ways of accessing our past that depend on different regions of the brain.

What children with developmental amnesia teach us is that even if we don’t remember every experience in detail, they probably all contribute to our ability to understand the world around us.

*María del Carmen Martín-Buro García de Dionisio is a professor of Experimental Psychology at the Rey Juan Carlos University, in Spain

This article was originally published on the academic news website The Conversation and republished under a Creative Commons license. read here the original version in Spanish.