To Consolidate Odor Memories, Nematodes Require a Nap: Findings from Experiments

A team of biomedical researchers from the University of California, San Francisco, San Jose State University, and the University of Pennsylvania found that nematodes need sleep in order to consolidate odor memories by remapping olfactory synapses. In the study, it was stated in cellThe group studied nematodes and the behavior of synapses during sleep.

Previous research has shown that one of the reasons animals sleep is to help the brain consolidate long-term memories. Previous research has also suggested that such memories are stored in synapses in the brain rather than in neurons. In this new effort, the researchers focused their efforts on nematodes because their brain structure had already been determined—they only have 302 neurons. The team hoped to observe changes in synapses during periods of sleep. But first, they had to figure out a way to know for sure when the little creatures were sleeping.

A careful study of multiple samples showed that the sleep of nematodes can be determined by a certain body position. Once this was established, the team trained several samples to ignore the smell of butanone, which they usually find very attractive. They did this by removing the food associated with the smell on multiple occasions. The researchers then took a closer look at the nematode’s brains, specifically at a neuron called the AWC, which is known to communicate with another neuron called the AIY.

They found that training the worms to ignore butanone caused a decrease in synapses between AWC and AIY neurons. The team then trained the other worms to avoid the smell of butanone, but this time did not allow them to nap afterwards. And this time, they found denser synaptic connections between neurons — they also found that the worms didn’t remember the training they had received.

The researchers suggest that the short nap allowed synapses to reprogram, which in turn allowed the memories to fade.

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