MAY 04, 2019 7:50 AM PDT

How Worms Can Help Researchers Learn More About PTSD

WRITTEN BY: Carmen Leitch

Memory often involves associating two things - the color of a traffic light indicates whether to stop or go; or Pavlov’s dogs linked the sound of a bell to mealtime, for example. Animals and humans need associative learning to survive, in part by anticipating things that will happen. But we don’t know much about how memories are used to prepare for adversity. Scientists in the Genetics Department of Hebrew University wanted to learn more about how animals learn from past events and use them for the future. They found that even a simple creature like the nematode worm C. elegans can form these kinds of memories. Reporting in Current Biology, the team found the neurons that contain these memories, and the cellular processes that occur as worms use those memories to deal with life.

A naive worm, that did not go through the training, likes the scent and lingers nearby.

"We trained the worms to form associative memories,” explained Dr. Alon Zaslaver. "However, that instead of feeding the worms like with Pavlov's dogs, we starved them for a day, and instead of ringing a bell, we sprayed a scent that the worms like. We hoped that by linking this odor with hunger, the worms would learn that from now on this pleasant odor signals a distressed situation."

The day after the worms had been trained, the worms were well fed and exposed to the smell again. They reacted, quickly getting into a defensive mode and activating genes that protect against stress. What was once a pleasant scent now had a totally different impact; the worms had associated the smell with a stressful lack of food. But experiencing that stress seemed to have equipped them to deal with it.

"However, when we again subjected the worms to starvation, they were better able to survive the hardship than before their associative-learning training. In a way, their PTSD had helped them," Zaslaver explained.

C. elegans is a great model in part because it is so simple - it only has 302 neurons. "It was wonderful to pinpoint the exact neurons that hold associative memories. It's very rare that you can look at a neuron and say 'Here, here is the memory,’" added Zaslaver. 

This worm learned to associate the pleasant scent with starvation. Therefore, it is repelled by the scent contained in the red stripe and won't cross it.

After the researchers found the memory-containing neurons, they engineered new worms using optogenetic techniques; the neurons controlling the fight-or-flight instinct were activated when a light shined on them. Now they didn’t need to use the odor, the neurons where starvation memories resided could be activated, and the worms got stressed.

Humans exhibit a similar response in post-traumatic stress disorder (PTSD). PTSD develops after a traumatic event. Something like a scent or visual stimulus can trigger memories of the event, causing anxiety attacks and stress disorders.

The team wants to use this work to gain new insight into PTSD, and potentially to identify new treatments.


Sources: AAAS/Eurekalert! Via Hebrew University of Jerusalem, Current Biology

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
JAN 11, 2020
Cell & Molecular Biology
JAN 11, 2020
To Save Others, Bacteria Can Self-Destruct When Infected by a Virus
Scientists were studying viruses that infect and kill bacteria as a medicine for bacterial infections over a hundred years ago, and they are a focus of recent research as well....
JAN 27, 2020
Cell & Molecular Biology
JAN 27, 2020
The 3D Ultrastructure of a Cell is Revealed
Seeing what's going on inside of cells presents many challenges that advances in microscopy have tried to address....
FEB 01, 2020
Cell & Molecular Biology
FEB 01, 2020
Immunity in the Gut Ramps Up Around Mealtimes
Scientists have found that our immune system benefits when we eat regular meals....
FEB 24, 2020
Cell & Molecular Biology
FEB 24, 2020
How Brain Cells Can Protect Muscles
Protein buildup is not only a problem for the brain, it can also impair muscles....
MAR 16, 2020
Genetics & Genomics
MAR 16, 2020
How To: Recombinant Protein Construct Design
Creating recombinant proteins has become much easier over the past few decades. However, those with the skills to do design such constructs are usually lim...
MAR 22, 2020
Cell & Molecular Biology
MAR 22, 2020
Capturing Images of Firing Neurons
Our bodies run on electricity. Neurons send rapidly fired electrical signals through the brain and limbs constantly, enabling us to think and move....
Loading Comments...