Under the Hood

Worms Found Beneficial In Human Brain Studies: Scientists Decipher Kamin Blocking Mechanism

Scientists have found that roundworms could be used to help understand what causes memory blocking, a finding that could help decipher how people struggle to remember and associate events.  

Memory blocking, also known as Kamin blocking, occurs when the brain refuses to replace an old memory cue with a new one if both cues are brought up at the same time.

"Suppose you grew up hearing ice cream trucks playing a song and hearing that song, even when you can't see the truck, makes you think of ice cream," Daniel Merritt, professor of molecular genetics at the University of Toronto, said.

"One day, the ice cream truck owners decide to add a spinning green light to the roof of the truck, so that even people who are hard of hearing can see them. Kamin blocking predicts that you won't learn to associate spinning green lights with ice cream, because the ice cream truck song already fully predicts the delicious treat in store for you," he explained. 

To further understand Kamin blocking, Merritt and his research team analyzed the more 300 nerve cells inside roundworms. The professor said they found worms to be simple test models to study the molecular changes in the brain that affect memory. 

For the study, published in the journal Nature, the team trained worms to associate hunger with either the taste of salt or the smell of benzaldehyde. Researchers found the worms tend to crawl toward the taste despite being exposed to benzaldehyde aroma.  In a second experiment, the researchers placed green fluorescent molecules in the heads of the worms to observe the EGL-4 protein, which indicates benzaldehyde starvation learning. The team repeated the salt and benzaldehyde test and found the EGL-4 protein behaved the same way during benzaldehyde blocking as it did during normal learning.

"This is interesting because it contradicts the classic interpretation of blocking where you need an element of surprise or you don't bother remembering the second association," Merritt said. 

He added the findings indicate that despite a memory being formed, the expression of behavior remains suppressed somehow, which may have affected how the subjects remember events. 

Worm Scientists have found a way to better understand how memory blocking occurs in humans by studying worms. Pictured: Vinegrowers from the Cotes de Provence in Figuiere spread earthworms around the vines as an experimental approach, hoping to enrich the naturally poor soils of the region, on May 29, 2018 in La-Londe-Les-Maures, southern France. Anne-christine Poujoulat/AFP/Getty Images

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