Scientists Have Discovered Which Region of Rats’ Brains Becomes Active When they Giggle
What occurs in the brain during tickling? Back in 1999, researchers discovered that rats emit vocalizations similar to humans when tickled. The question arises: do they laugh or react aggressively due to irritation?
At the neurobiological level, studies have successfully identified brain regions responsible for fear, reward, sensory processing, and cognition, but the understanding of play has remained relatively limited.
Unraveling Brain Activation and Play Impact
To gain insights into brain activation during tickling and its impact on rats’ gray matter, a research team in Germany focused on identifying the specific brain region involved. They found that the periaqueductal gray (PAG) structure in rat brains plays a crucial role in facilitating play and laughter.
The brain’s “play spot” is situated in the midbrain and is known as the periaqueductal gray (PAG). This crucial structure is responsible for regulating pain, sympathetic responses, defensive behaviors, and aversive actions.
Insights from Senior Author Michael Brecht
Senior author Michael Brecht, a neuroscientist at the Humboldt-Universität zu Berlin and co-author of the study, explained, “We recognize that vocalizations like laughter play a vital role in play behavior, suggesting that there is a specific brain signal organizing this behavior.” He further added, “For instance, children tend to check for laughter while engaging in playful fighting. If their playmate stops laughing, they cease the fight.“
However, rats are not as prone to laughter as humans are. To ensure the rats were at ease, the researchers allowed them to freely move around for a couple of days and get accustomed to human interaction. When amused, rats emit high-pitched squeaks that are inaudible to humans. The researchers monitored these sounds to confirm the rats’ enjoyment.
Role of the Periaqueductal Gray (PAG) in Rat Behavior
The study revealed that the periaqueductal gray (PAG) in the rats’ brains became active during tickling. When the PAG was inhibited or turned off, the rats played less and laughed less frequently. This behavior was also observed when the rats were placed in anxiety-inducing situations.
In another study conducted in Australia, researchers tickled rats daily for a month to assess its potential impact on their emotional well-being. Previous research had already demonstrated that rats suppress their laughter when tickled under stressful circumstances but giggle more in relaxed environments. Michael Brecht was a co-author in this study as well.
Exclusively Male Rat Participants
One limitation of the research, highlighted by neuroscientist Margaret McCarthy from the University of Maryland School of Medicine in a discussion with Scientific American, is that only male rats were used in the study.
McCarthy expressed her desire for future follow-up studies to incorporate female rats as well, considering the distinct behavioral responses observed in male rats, which are known to have differing rates of play compared to their female counterparts.
Read the original article on Interesting Engineering.
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