Proust’s madeleine effect: what is it, its characteristics and causes?

Proust's madeleine effect gives us clues about how our brain and our memory work.

Surely on more than one occasion you have perceived a smell that was somehow familiar to you and a very specific memory has automatically come to mind.

How is this possible? Thanks to Proust's madeleine effecta phenomenon that we are going to deepen below so that you know its neurological explanation.

What is the Proust's madeleine effect?

Proust's madeleine effect is a cerebral association that we make automatically when we perceive a certain sensation through our senses, generally through the sense of smell.The most incredible thing is that this memory may have been dormant for years or even decades, buried deep in our neural networks, and we may well believe that we had forgotten it completely until this unexpected automatic retrieval of the memory occurs.

The most incredible thing is that this memory may have been dormant for years or even decades, buried in the depths of our neural networks, and we may well believe that we had completely forgotten it until this unexpected automatic recovery occurs.

The expression as such of "Proust's madeleine effect" comes from the author of the same name, Marcel Proust, who in 1913 published his work On the Road to Swann. Specifically, in the first of its volumes, entitled In Search of Lost Timewhich begins with the protagonist preparing to taste a freshly baked madeleine, and when he decides to dip it when he decides to dip it in the glass of hot tea and puts it in his mouth, the sensations perceived transport him directly to the memories of his earliest childhood.. In fact, the novel is composed of more than 3,000 pages in which the events that the protagonist recalls as a result of this situation are narrated.

Therefore, the origin of this expression would be merely literary, but after more than 100 years of travel, has taken root both in science and in popular culture.It is therefore relatively easy to find it in neurology studies or in marketing manuals, as well as in many other fields. Other terms that we can find are Proustian effect or Proust phenomenon, but all of them refer to the same phenomenon, indistinctly.

Biological basis of this memory phenomenon.

We already know what the Proustian madeleine effect consists of. Now let's see what are the causes at the neurological level for us to experience something as incredible as the automatic unlocking of a forgotten memory, simply with the power of a smell, a taste or other perceived sensation.

It seems that the part of the brain responsible for this matter would be the limbic systemIt seems that the part of the brain responsible for this matter would be the limbic system, since in this region there is a meeting of different structures, with very different functions, but which apparently can converge and make the most surprising associations between emotions, memories and perceptions.

Let's take a closer look at some of these brain sectors in order to better understand how Proust's madeleine effect can be generated.

1. Thalamus

The first structure that we find within the limbic system is the thalamus, which in itself already has an important set of functions, which will be vital to study the phenomenon that concerns us. The thalamus processes the information received by the senses, before being forwarded to the corresponding brain regions that finish integrating this data..

But not only that, it is also involved in processes related to memory and emotions, so it would already be giving us a lot of information about a key place in the brain where very different functions take place but that somehow can be associated by shared neural networks.

2. Hypothalamus

Another of the key brain structures in Proust's madeleine effect is the hypothalamus, a well-known region of the brain where an infinite number of processes take place, but the ones that interest us in this case are those related to emotions.. The hypothalamus would have control over emotional expression at the physiological level.

3. Hippocampus

Also in the limbic system we will find the hippocampus, an area of the brain of vital importance for the creation of new memories.The brain is an area of the brain that is vitally important for the creation of new memories, as well as other functions that are equally important but not relevant to explain Proust's madeleine effect.

4. Amygdala

Finally we would find the amygdala, another of the brain regions that share responsibility in this phenomenon, in this case because some of its functions are those intended to manage the emotionality of our reactions, also helping to generate memories impregnated with a specific mood or emotion..

The power of smell

It is worth pausing for a moment to take an in-depth look at the characteristics of the sense of smell, the most powerful sense when it comes to triggering Proust's madeleine effect in us. We have already seen that smell, memory and emotions share certain neural circuits in our brain.

It should be noted that humans are able to remember up to 10,000 different smells.. In fact, we retain in our memory 35% of the information that comes to us through smell, and only 5% of what we capture through vision, which is still a huge amount of data, since it is the way by which we receive more stimuli from our environment.

These characteristics make the sense of smell a powerful trigger of memories.These characteristics make smell a powerful trigger of memories, since many of those that are recorded in our memory are associated with the context of the situation experienced at that moment, so that capturing a certain scent again will make us mentally travel back to that pleasant situation that marked the first time we registered the characteristics of a certain smell in our brain.

But be careful, because this mechanism does not understand positive and negative stimuli, and just as the smell of, for example, a certain infusion, can transport us to a pleasant place and make us relive a magnificent summer, the opposite can also happen and instead bring back to our mind a certain event that was unpleasant at the time it happened and that we had completely forgotten, or so we thought.

Special mention should also be made of the sense of taste, since it usually works in tandem with the sense of smell when it comes to food and beverages.. It is difficult to separate the sensations we perceive through the nose and the mouth when we are tasting a succulent stew, an intense coffee, etc.

Practical applications

In some types of psychological therapy such as EMDR, based on the reprocessing of traumatic events, it is possible to resort to techniques that, although they do not exactly use Proust's madeleine effect, use a strategy whose mechanism is very similar in its foundation to help patients with traumatic events, use a strategy whose mechanism is very similar in its rationale to help patients with traumatic events..

In this case, what the therapist who is treating the trauma would do would be to ask the subject to think of a smell that is pleasant for a given reason (or, if circumstances permit, to actually smell that stimulus, e.g. a perfume or a particular food).

In this way, the neural networks that had previously associated that stimulus with certain people, places or moments that are positive for the subject, would bring that positive memory to the person's mind.This would reduce their physiological activation and facilitate the reprocessing of the traumatic event experienced and being treated in the consultation.

Smell and memory

But the relationship between the sense of smell and our ability to generate and retrieve memories goes far beyond what we have seen with Proust's madeleine effect. The relationship is so close that many neurological studies investigate the correlation between dementia and loss of smell..

In fact, for one of the most serious neurodegenerative diseases, such as Alzheimer's, one of the indicators taken to diagnose whether the person is at the beginning of this disorder would be precisely the problems to capture smells, and the loss of smell is associated with dementia, sharing, as we have seen, brain structures that in this case would be damaged and would cause sequelae in both capacities.

Specifically, the critical point of the brain that when damaged causes this type of alterations would be the circuit that connects the hippocampus, a structure that we have already seen, with the anterior olfactory nucleus, which in turn is part of the olfactory bulb, located in the forebrain.

For all these reasons we should be aware of the power of the sense of smell, not only because of such curious phenomena as Proust's Madeleine effect, but also because it is a valuable indicator that, in its absence, can set off alarms about a possible memory impairment.

Bibliographical references:

• Rodríguez-Gil, G. (2004). The powerful sense of smell. California services for deaf-blindness.
• Miranda, M.I. (2011). The taste of memories: formation of taste memory. Mexico. DGTIC University Repository.
• Bonadeo, M.J. (2005). Odotype: Natural History of Smell and its role in brand identity. Buenos Aires. Universidad Austral.
• Aqrabawi, A.J., Kim, J.C. (2018). Hippocampal projections to the anterior olfactory nucleus differentially convey spatiotemporal information during episodic odour memory. Nature communications.