Neuroscience and Laughing Rats as the Future of Mental Health

In mid-November last year, a polygamous group of rats moved into the vivarium in the basement of Chemicum, where each male rat was accompanied by two female rats. As a result, by 2024, the rat population in the basement had multiplied significantly, and members of the neuropsychopharmacology research group began spending time studying the rats, including tickling them.

Although tickling rats may seem like a peculiar activity at first, it provides valuable insights into emotions and brain function. According to the theory of Estonian-born American psychologist and neuroscientist Jaak Panksepp, emotions are deeply rooted in brain structures located beneath the cortex. Studying rat tickling allows researchers to model how positive emotions are linked to brain neurochemistry and behavior.

Scientists have observed that in response to tickling, rats produce high-frequency, 50-kilohertz ultrasonic vocalizations, which resemble laughter. These vocalizations suggest that rats experience joy, and their individual capacity to feel joy varies and remains stable over time. Research findings have shown that the "happier" rats are also more resilient to stress. This raises the question: how do "less happy" rats differ, and what are the specific characteristics of their brains compared to the "happier" ones?

A persistently low level of joy in humans can indicate mood disorders such as depression. These conditions often involve dysfunctions in monoaminergic systems—serotonin, dopamine, and noradrenaline. Research group member Karita Laugus explains that the levels of these monoamines and their responses to stimuli can be measured using chromatographic methods in brain tissue or the extracellular space, utilizing in vivo microdialysis techniques.

Such studies help develop new methods to alleviate mental health issues like depression and anxiety disorders. By gaining a better understanding of how positive emotions function in the brain, we can find ways to foster these emotions and thereby improve human mental well-being.