Learning is one of the most important mental processes for living beings; To know the world, living beings must discriminate between the most important environmental stimuli, as well as keep track of changes that occur over time.
So far, this phenomenon has remained unknown to science. Recently, a team of researchers has discovered how animals classify the stimuli they receive from the environment; Furthermore, there is evidence on the neurophysiological basis of this process.
To learn it is necessary to discriminate between the most relevant stimuli
There are several learning processes, some more complex than others; in its simplest form, learning can be reduced to a feedback process; For example, if after eating certain types of food a person is severely weakened, it is unlikely that he will feel the desire to eat the same kind of food. To achieve this, it is necessary to know what to learn, distinguishing between important information and irrelevant stimuli.
To understand this process, a team of researchers designed an experiment with mice. In particular, they have taught rodents to associate certain aromas with appetitive or adverse consequences; a smell signaled the appearance of a sip of water, while the other was the sign of a direct breath of air on the face.
Subsequently, the scientists replaced the air with an electric discharge, with the premise that this would have been more surprising. While this was happening, the researchers evaluated mice activation patterns. In this way, it has been discovered that a brain structure, called paraventricular thalamus, has the function of identifying and tracking the most important stimuli of the environment in a given context.
The paraventricular thalamus is the brain structure that identifies the most relevant stimuli
Specifically, when the researchers used the breath, two thirds of the paraventricular thalamus neurons were activated; On the other hand, when the aroma associated with the sip of water was used, an additional 30% of the neurons were activated. Briefly, during this phase, the paravirricular thalamus was similarly activated prior to appetitive and adverse stimuli.
On the other hand, when electrical discharges were used, the result was the opposite, since most neurons responded to the adversarial stimulus, while only 75% of them were activated by the appetitive stimulus. This reflects that when electrical discharges were used, water stopped being so important for mice.
In addition to this, the researchers used genetic modification techniques to control the activity of the paraventricular thalamus with light stimuli; from this they discovered that it was possible to inhibit or improve learning.
Given the results, the researchers conclude that the paraventricular thalamus is the brain structure responsible for delimiting the importance of environmental stimuli; that is, this area has the function of tracking the most important stimuli according to the situation.
Finally, the researchers point out that while these results are only applicable to mice at the moment, in the future, thanks to the discovery, it would be possible to fully understand the learning process in humans; this could promote the treatment of problems such as drug addiction.
Reference: dynamic elaboration of the salience in associative learning of the paravirricular thalamus gates, (2018). https://www.doi.org/10.1126/science.aat0481