US, WASHINGTON (ORDO NEWS) — Researchers have taught the computer to determine which emotion corresponds to one or another expression of the muzzle of laboratory mice. Thus, scientists have received a quick and impartial method that allows you to recognize the feelings of these animals.
Achievement opens up new perspectives in the study of the neurobiology of emotions, including human ones.
Details are set out in a scientific article published in the journal Science.
Emotions are a huge part of our lives. Naturally, scientists seek to understand the underlying mechanisms of brain function. They are driven not only by the desire to know themselves, but also the desire to help people with emotional disorders, such as depression or bipolar disorder.
For obvious reasons, not all experiments can be carried out in humans . In such cases, animal experiments are usually conducted. And here the scientists are in wait for a trick.
How to understand what emotions a laboratory mouse experiences? After all, the facial expressions of animals are not like human ones. For example, for dogs to bare their teeth is not a friendly smile, but a menacing grin.
Experienced experts master the art of recognizing the emotions of mice, but this procedure remains long, time-consuming and subjective. The most difficult thing is to determine the intensity of a particular emotion.
A team of scientists from three research centers in Germany set out to make the recognition of emotions in mice quick and objective. To do this, they brought in computer technology.
Researchers have selected stimuli that are guaranteed to provoke one or another experience in rodents. Biologists did not try to provide their subjects with inspiration or lyrical thoughtfulness, it was about the most basic feelings.
So, dainty certainly gives the animal pleasure. At the same time, a bitter or very salty liquid disgusts, and an injection of lithium chloride responds with nausea. It is also easy to scare the animal or hurt it.
The experimenters captured the facial expressions of rodents on video with a high frame rate. Note that the cheeks, ears, eyes and nose of the caudate participated in mimic movements.
Then, individual shots were processed by artificial intelligence. Part of the images was used to train an artificial neural network , and another part was used to verify the result.
As a result, the system learned to quickly and fairly accurately recognize the five basic “facial expressions” of mice: pleasure, disgust, pain, fear and nausea. The computer not only distinguished one experience from another, but also determined their intensity.
Experts were also convinced that the conditions behind mouse facial expressions can indeed be considered emotions. There are several criteria for this. Firstly, emotions are stable: they persist for some time even after the termination of the stimulus. Secondly, the strength and nature of the experience should depend on the intensity of the impact.
So, the mice liked the slightly salted liquid, and the excessively salty was disgusting. Thirdly, not only the stimulus is important, but also the condition of the subject receiving it. So, a hungry animal feels much more pleasure from delicacies than well-fed.
Scientists checked their results in another way. Using optogenetic methods, they acted on individual neural circuits in the mouse brain. In previous studies, it was shown that in humans, the activation of these chains causes certain emotions.
For example, by stimulating a certain part of the island , you can provoke a strong disgust. Biologists are convinced that this effect is also reflected in the facial expressions of the mouse, as well as tasting the bitter liquid. That is, the rodent was really disgusted. The situation was similar with the brain zones responsible for other emotions.
To demonstrate the potential of their method, neuroscientists “turned” the last task. They caused the animal experiences by conventional methods such as a delicious treat or electric shocks on the tail and observed which nerve cells are activated. In this way, they identified neurons that are activated if and only when the mouse experiences a specific emotion. In other words, scientists have identified pleasure neurons, fear neurons, and so on.
So, the technique worked: being able to read emotions directly from the mouse “face muzzle”, the researchers began to elucidate the neural basis of their rich inner world. If such an approach proves effective in independent research, it will be adopted by neuroscientists around the world. And then, probably, we will learn more about emotions than ever.
Contact us: [email protected]
The article is written and prepared by our foreign editors from different countries around the world – material edited and published by Ordo News staff in our US newsroom press.