LOAN: University of Linköping
Crickets that are exposed to drugs that alter serotonin levels in the brain are less active and less aggressive than crickets that have not been in contact with medication, according to a new study by scientists at the University of Linköping. The results were published in Scientific reports.
People on many species of animals display different personality types. Some people are, for example, consistently bolder than others.
"However, in biology, we still do not fully understand what causes people or animals to have differences in personality: people who have different levels of brain chemistry, such as serotonin and dopamine, often behave differently if these chemicals can explain personality differences also in other species and if the chemicals cause observed differences or if both differences in behavior and chemical levels are caused by another underlying factor, "says Robin Abbey-Lee, a postdoctoral doctor at the Department of Physics, chemistry and biology, IFM and lead author of the study .
Researchers have therefore decided to experimentally change levels of serotonin and dopamine in brain crickets. They did this by giving crickets to human pharmaceuticals that are known to act on serotonin and dopamine systems and are used to treat depression and Parkinson's disease, respectively. Because dopamine and serotonin systems are similar in different species, it was predicted that these chemicals would also affect cortical behavior.
"In this study, we wanted to face a significant gap in our knowledge, experimentally changing these brain chemicals, and checking if we can get the resulting change in behavior," says Hanne Løvlie, associate professor IFM and lead author.
The researchers measured three different behaviors.
"First of all, we measured the activity of crickets in familiar surroundings, as was the case for a person moving around in their own home, and secondly, we measured the behavior of cricket exploration in a new environment, as well as the behavior of a man on a journey to a new city, and finally measured the cricket behavior, to determine how aggressive people are, "says Abbey-Lee.
Researchers have found that changing serotonin levels makes crickets less active and less aggressive. But changing the level of crickets in dopamin did not change their behavior.
"This suggests that serotonin plays a clearer role in these behaviors," says Hanne Løvlie.
The findings deepen our knowledge of why animals have personality. They also raise the question of how pharmaceuticals penetrating nature through human wastewater can affect animals.
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