Delivering electric shocks to 1mm-long roundworms may sound rather meanspirited, but scientists at Nagoya City University have used this particular stimuli to uncover some curious behaviors of Caenorhabditis elegans that could further our understanding of human emotional mechanisms and in turn treat disorders.
C. elegans have been a major focus of research for human medicine and treatments, such as looking into anti-aging mechanisms, because of shared genes and other surprising common aspects of their biology.
In this study, C. elegans were subjected to electrical stimulation and began moving away from the stimuli at high speed. While this is not unusual, given most animals’ instinctually flee perceived danger, the worms continued to ‘run’ for one to two minutes after the stimulation ceased. In most animals, abnormal behaviors cease once the stimulus has stopped.
“We unexpectedly found that C. elegans’ high-speed response persists after electric shock,” noted the researchers.
The worms’ behavior suggested to the researchers there was a unique mechanism at play akin to a primitive emotional response. Supporting this, the worms also ignored their usually prioritized food, bacteria, switching up the focus of what they considered more important to survival. Because they also use their food sources to read environmental information crucial to their survival, it was an unexpected change in primal instinct behavior.
“The lack of response to food during and following our electric stimulus might support this point as well, as the emotional state induced by electricity influences the response to food, an entirely different stimulus,” the researchers noted. “Taken together, these results may suggest that the animal's response to electric shock represents a form of emotion, possibly akin to fear.”
And not all worms behaved the same. Genetic analysis revealed that some animals with certain mutations were unable to produce neuropeptides, which are akin to human hormones. In these worms, the running behavior continued for much longer than in the other animals.
This prolonged ‘fear’ response gives scientists clues as to how much of a role genetics may play in emotional regulation – in both the well-studied C. elegans and in humans.
Emotional responses to stimuli may not just taper off naturally but be turned down by a genetic mechanism controlling its activity. The researchers believe there may be novel genes that regulate emotional responses, and as such may provide a new pathway to treatment for disorders such as depression and anxiety.
Previous studies on neurosensory behavior in these tiny worms have looked at how much they can process, while another has also noted their aversion behaviors in response to thermal stimuli.
This latest study was published in the journal Genetics.
Source: Nagoya City University
