The findings, published today in the scientific journal Nature Neuroscience, may shed light on the relationship between genetics and interpersonal differences in behavior
The general public may imagine laboratory mice as one piece, but scientists who work with mice every day know that no two mice are alike. But is it possible to conclude from these differences in behavior that mice - and other animals - have different personality types that characterize them? Recently, Weizmann Institute of Science scientists and their research partners developed a computational method for measuring personality traits in mice, and showed that mice are endowed with a unique personality that can predict their behavior in different situations. The findings, published today in the scientific journal Nature Neuroscience, may shed light on the relationship between genetics and interpersonal differences in behavior.
Personality is, by definition, a unique characteristic of an individual that remains fairly stable throughout his life. Humans are usually given personality scores based on multiple-choice questionnaires, but how do you measure personality in mice? Prof. Alon Chen, the elected president of the institute, and the research groups led by him - in the institute's neurobiology department and the Max Planck Institute for Psychiatry in Munich - developed a method of "reverse engineering" that makes it possible to tap into the character traits of mice by observing their behavior. The research team, led by Dr. Oren Furkosh, first observed mice that were divided into small groups and placed in normal laboratory environments that included food, shelter, and various types of games. The mice were allowed to communicate with each other and freely explore their environment, while being recorded using cameras for several days. The scientists analyzed the The behavior of the mice in the videos and mapped 60 types of behavior, such as the degree of approach to other mice, the tendency chasing each other or running away from each other, the tendency to share food and the tendency to be curious or hide.
Based on these findings, the researchers developed an algorithm that extracted from the many behaviors of the mice, features that characterize different personality types. This method works to a certain extent similar to personality tests in humans where the subjects are rated in five indices according to the "big five traits" model: extroversion/introversion, agreeableness, conscientiousness, neuroticism and openness to experience. In mice, the algorithm extracted four indices, and when the researchers assigned personality types to the mice based on their scores in the various indices, they discovered that each mouse is endowed with a unique personality that characterizes it and makes it possible to predict its behavior. To check that these traits are indeed stable, the researchers mixed up the groups - a stressful situation for the mice - and discovered that although some of the behaviors changed - sometimes even drastically - but the personal characteristics remained unchanged.
What can be learned from this method for diagnosing personality in mice? In collaboration with Prof. Uri Alon, from the department of molecular cell biology at the institute, the researchers sketched "personality spaces" - a form of analysis that compares two personality traits at a time, and yields triangles at the vertices of which three archetypes are located: for example, the archetype of the "village mouse" (dominant and aggressive), the "city mouse" archetype (dominant but sociable) and the "lab mouse" archetype the submissive This method of presenting the data allows for the analysis of evolutionary changes - for example, how the need to survive and thrive in a hierarchical environment affected the traits of the mice. "In fact," says Dr. Furkosh, "we see that these archetypes - and all the shades in between - have not disappeared, even though these mice have lived for generations in laboratory conditions, and most likely will not survive in the wild."
Later Stoyo Karmiheev, a research student in Prof. Chen's laboratory, mapped patterns of gene expression in the brains of the mice, and was able to identify genes associated with certain personality traits of these mice. "If we can identify the genetics of personality, we may be able to diagnose what happens when these genes go wrong and offer treatments accordingly," says Dr. Porkosh. According to the personality type. In addition, we can use the method to compare personality types of different species, thus gaining insights into the animals in our world."
Sergey Anfilov and Dr. Yair Shemesh from the Weizmann Institute of Science and the Max Planck Institute of Psychiatry, Markus Nussbaumer, Cornelia Fleckskam, Paul M. Kaplik and Simon Rua from the Max Planck Institute of Psychiatry and Prof. Chadi Touma from the University of Ossenbrick, Germany also participated in the study.
