Dopamine helps our brains to let go of memories

In a discovery that could reshape how we think about memory, researchers at Flinders University have shown that the brain actively forgets by utilising the same chemical that helps us learn: dopamine.

Published in the Journal of Neurochemistry, the team’s study used tiny worms called Caenorhabditis elegans — 1 mm long with only 300 neurons, yet 80% genetically identical to humans — to explore how memories fade. These microscopic creatures might seem worlds apart from humans, but their brains share many of the same molecular pathways, making them suitable for studying brain pathways including memory.

Researchers in the Flinders Health and Medical Research Institute’s Chew lab trained the worms to associate a specific scent with food, then observed how long the memory of that association lasted. Surprisingly, worms that could not produce dopamine held onto the memory much longer than normal worms. In other words, without dopamine, they took much longer to forget.

“We often think of forgetting as a failure, but it’s actually essential,” said neuroscientist Dr Yee Lian Chew, who co-led the new research. “If we remembered everything, our brains would be overwhelmed. Forgetting helps us stay focused and flexible.”

The team also discovered that two specific dopamine receptors (DOP-2 and DOP-3), which are similar to some dopamine receptors found in humans, work together to control forgetting. When both were disabled, the worms clung to their memories just like the dopamine-deficient ones.

Even when the researchers tried to restore dopamine in certain brain cells, it was not enough because the whole dopamine system needs to be working for forgetting to happen properly.

“We found that dopamine receptors in the worm that are similar to those found in humans play a role in regulating this forgetting behaviour,” Chew said.

“This research could help us understand human memory because dopamine plays a major role in conditions like Parkinson’s disease, where memory and learning can be affected.

“We are now trying to identify exactly how dopamine acts on neurons in the brain to ‘forget’ old memories.

“We think this may have implications for gradual memory loss during healthy aging, or in dopamine-related neurodegenerative diseases such as Parkinson’s disease.

“By understanding how dopamine helps the brain let go of memories, we may one day find new ways to support people with memory-related disorders.”

The research builds on similar findings in fruit flies, suggesting that dopamine-driven forgetting is a universal brain function.

“It’s exciting to see that something so fundamental is shared across species,” Chew said.

“It means we’re tapping into a deep biological truth which helps us lay the groundwork for breakthroughs in human health.”

Image credit: iStock.com/Deagreez