Worms illuminate ancient emotional mechanisms

summary: Researchers have discovered that the humble roundworm may hold insight into basic emotional mechanisms. When exposed to electric shocks, these worms displayed behavior consistent with a primitive form of emotion, prioritizing danger over food.

By taking advantage of genetic analysis, the study suggests that these reactions may be governed by an active genetic mechanism, highlighting the roots of emotions that exist even in complex organisms such as humans. This foundational research could pave the way for new treatments for affective disorders.

Key facts:

1. The roundworms showed behavior consistent with basic “emotions” when subjected to electric shocks, including prioritizing escape over food.
2. Genetic analysis revealed that neuropeptides (similar to our hormones) play a role in regulating this “emotional” response, suggesting the possibility of an active genetic mechanism behind emotions.
3. The discovery of emotion-related genes in worms could provide potential targets for treating human affective disorders, given their genetic similarity.

source: Nagoya City University

Brain research is one of the most important areas in the modern life sciences, and “emotion” is one of its main topics. Studying emotions in animals has long been considered a challenge, with limited research focusing mostly on “fear” in mice and rats.

Since 2010, it has been increasingly reported in scientific papers that even crayfish and flies may have brain functions that resemble emotions by focusing on several characteristics of their behavior, such as persistence and valence.

For example, when an animal faces a dangerous situation such as being attacked by a predator (negative valence) even for a short period of time, the animal’s behavior may be to stay in a safe place, ignoring the usually attractive odors of food even if it is hungry, for a certain period of time (persistence ), which a primitive form of emotion can regulate. However, the details of these basic “mechanisms of emotion” remain largely unexplained.

An international research team from Nagoya City University (Japan) and Mills College at Northeastern University (USA) has revealed the possibility that the roundworm Caenorhabditis elegans possesses basic “emotions.” They used worms because worms have been used for detailed analysis of basic functions such as perception, memory, and even decision making at the cellular and genetic levels.

The research was published in Genetics.

The team first discovered that when exposed to alternating current stimulation, the worms began moving at an unexpectedly high speed. Interestingly, the team also found that this “running” response persisted for a minute or two even after the electrical stimulation had ended for a few seconds.

In animals in general, when a stimulus is stopped, the response to that stimulus usually stops immediately. (Otherwise the perception of stimuli such as sounds or visual sights would persist.) So the “keep running even after the stimulus stops” reaction is exceptional.

Furthermore, during and after electrical stimulation, the team found that the worms ignored food bacteria, which provide important environmental information. This suggests that while the presence or absence of food bacteria is usually critical, the risk posed by electric shock, a survival-threatening stimulus, is even more important.

In other words, when worms sense the dangerous stimulus of an electric shock, their top priority for survival is to escape from that location. To achieve this, the brain’s performance appears to be constantly changing, including ignoring normally important “food” in order to escape danger. This suggests that the phenomenon of “worms continuing to run due to short-term electrical stimulation” reflects basic “emotions.”

Furthermore, through genetic analysis, especially taking advantage of the worms’ advantages, the team revealed that mutants unable to produce neuropeptides, the equivalent of our hormones, showed a longer duration of continuous running in response to electrical stimulation compared to normal worms.

This result suggests that the ongoing state in response to danger is regulated to end at the appropriate time. In fact, if we experience excitement or fear that lasts for too long, it disrupts our daily lives.

Therefore, the findings suggest that our emotions, such as “excitement,” “happiness,” or “sadness,” triggered by stimuli, may not be destined to fade away naturally over time, but are controlled by an active mechanism involving genes.

This study shows that using worms can provide detailed insights into the genetic mechanisms underlying primitive “emotions.” It is known that many of the genes that work in worms have counterparts in humans and other organisms, so this study Worms It could provide important clues about the genes involved in the basis of “emotions.”

Specifically, conditions such as depression, classified as mood disorders, can be explained as conditions in which negative emotions are excessively and persistently maintained due to an inability to effectively process experienced stimuli. If new genes associated with emotions are discovered through worm research, these genes will likely become targets for new treatments for emotional disorders.

About this emotion and evolutionary neuroscience research news

author: Ling Fei Te
source: Nagoya City University
communication: Ling Fei Te – Nagoya City University
picture: Image credited to Neuroscience News

Original search: Open access.
“Electric shock causes a persistent escape-like behavioral response in the nematode Caenorhabditis elegans“By Ling Fei Te et al. Genetics

a summary

Electric shock causes a persistent escape-like behavioral response in the nematode Caenorhabditis elegans

Behavioral stability reflects internal brain states, which underlie multiple brain functions. However, experimental models that enable genetic analyzes of behavioral stability and associated brain functions have been limited. Here, we report novel and persistent behavioral responses induced by electrical stimuli in nematodes Caenorhabditis elegantis.

When animals eating bacterial food are stimulated by alternating current, their movement speed suddenly increases by 2 to 3 times, continuing for more than 1 minute even after a 5-second stimulation.

Genetic analyzes reveal that voltage-gated channels in neurons are required for responding, perhaps as sensors, and neuropeptide signaling regulates the duration of sustained responding. Additional behavioral analyzes indicate that the animal’s response to electric shock is scalable and has a negative valence.

These characteristics, along with persistence, have recently been considered essential features of emotion, suggesting that C. elegans The response to an electric shock may reflect a form of emotion, akin to fear.