A study reveals surprising data on the brain's decision-making process.

A study by the Hospital del Mar Research Institute in Barcelona has advanced our understanding of how the brain makes decisions and participates in storing associations between different stimuli.

This study, conducted by the research group on cellular mechanisms in physiological and pathological behavior at the Hospital del Mar Research Institute, has been published in the journal PNAS and increases our understanding of how the brain makes decisions and which areas are involved in this process.

Researchers highlight the role of the amygdala and its relationship with parts of the cerebral cortex , and the discoveries may lead to therapeutic applications for mental disorders such as psychosis or post-traumatic stress disorder.

The study was conducted with mice, but researchers believe the mechanisms may be the same in humans.

They explain that the brain makes decisions based on direct associations between environmental stimuli, but it often does so based on facts that, in principle, are unrelated to each other.

Indirect associations

Based on observations with mice, carried out primarily by the article's first author, PhD student José Antonio González Parra, it has been possible to establish the mechanisms involved in the process by which the brain makes decisions based on indirect associations between different stimuli.

That is, this researcher points out, it does not occur through a direct association between a particular stimulus and a reinforcing or aversive situation, but rather through the relationship that is established between two or more stimuli .

The research project aims to understand how the brain enables decisions to be made based on indirect relationships between environmental stimuli.

In this sense, the mice were subjected to different behavioral tests , and for example, they were made to associate a certain smell - banana - with the sweet taste, and then another smell - almond - with the salty taste.

Positive and negative stimuli

They were then subjected to a negative stimulus, associated with the smell of banana.

From this moment on, the mice rejected the sweet taste , linked to the smell of banana and with a negative connotation, or what is the same, an indirect relationship was established between the sweet taste and the aversive stimulus, through its association with a specific smell.

The researchers used genetic techniques through viral vectors and were able to observe which areas of the mice's brains were activated throughout the entire process of coding and consolidating associations.

Thus, they verified how the amygdala, a region of the brain linked to responses such as fear and anxiety and which participates in certain mental pathologies - such as psychosis and post-traumatic stress - is activated when the mouse associates olfactory and taste stimuli .

At the same time, they saw that other areas of the brain were also involved in the process and interacted with the amygdala, and using imaging techniques, they established its relationship with a part of the cerebral cortex.

Brain circuit identified

The research team identified a brain circuit that controls associations between stimuli and allows these indirect associations to be made.

He also confirmed that if the activity of the amygdala was inhibited when the mice were exposed to the stimuli , the animals were not able to make these indirect associations.

The data obtained in the study may be relevant when treating certain mental disorders linked to amygdala activity.

In the future, one could consider brain stimulation or modulation of activity in the areas studied in people with post-traumatic stress or psychotic symptoms.