Zebrafish Study Reveals Some Of Us Might Feel Anxious Trying To Socialize After Lockdown

Zebrafish get lonely too. Neryxcom/Shutterstock

Rachael Funnell 11 Jun 2020, 18:23

For what feels like years, over half the world’s population has been impacted by some form of lockdown as a result of the Covid-19 pandemic and whether you’re normally a social butterfly or someone who likes to keep to themselves, you’re probably experiencing some side effects from the isolation. A somewhat counterintuitive but nonetheless prevalent emotional response to being kept from our loved ones is feeling a decreased desire for social interaction. A new study published in the journal eLife decided to investigate the mechanics of this paradox by observing social behavior in zebrafish.

Zebrafish are mostly social animals but around 10 percent are what the study term “loner” fish, in that they not only don’t share the typical zebrafish desire for social behavior but also exhibit different brain activity to their socialite siblings. The propensity for socializing can be changed by keeping a social zebrafish in isolation but the researchers weren’t sure if this behavioral change amounted to a change in the zebrafishes’ brain activity, mimicking that of the “loner” fish.

To find out, the researchers removed typically social fish from their group of buddies and placed them into isolation for two days. They then compared their brain activity to that of the “loner” zebrafish who weren’t keen on social interaction even without having been isolated. Their findings revealed that social fish in isolation experienced heightened sensitivity to stimuli and increased activity in the regions of the brain that related to stress and anxiety when returned to their tank mates, but these negative symptoms could be quickly overcome with anxiety medication.

Zebrafish raised in isolation display different social preferences from those raised normally. Tunbak et al 2020

The biggest differences between the social and loner zebrafishes’ brain activity were seen in the hypothalamus, which is the area of the brain tied to social rewards. Reduced activity in the loner fish indicated that they simply don’t experience the same rewards as their social counterparts from interacting with other fish. This differs from the “forced” loner fish who became antisocial after being put in isolation, as for these fish they experienced actively negative side effects such as sensitivity, stress, and anxiety when placed back with their tank mates.

"A detailed view of the zebrafish brain can provide important clues for all of us currently experiencing the effects of social isolation," said Dr Elena Dreosti of UCL in a statement. “Although human behaviour is much more complex, understanding how this basic social drive arises, and how it is affected by isolation, is a necessary step towards understanding the impact of the social environment on human brains and behaviour.”

If generalizable to humans, the research indicates that some of us may feel anxious upon reanimating our social lives, but this is a necessary step in returning to “normal” life. Fortunately, unlike the zebrafish, we have a wealth of sources to turn to if things prove difficult, as well as these wise words from a learned seal to see us through darker days.


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