The Genetics Of Fear And Empathy

Scientists have studied observational fear in mice to find out how empathy might work in humans.

AsianScientist (Apr. 25, 2018) – South Korean researchers have identified a genetic variant that controls and increases empathy-driven fear in mice. Since empathy is evolutionarily conserved from rodents to humans, these findings published in Neuron might help deepen our understanding of conditions characterized by a lack of empathy, such as autism, psychopathy and schizophrenia.

The capacity to understand and share another’s emotions can motivate compassion, sympathy and altruism. However, since empathy is a complex social phenomenon, its genetic and neurological roots are not easy to explain.

To study empathy in mice, the team from the Institute for Basic Science carried out observational fear tests on mice. When the mice observed other mice receiving a mild electric shock to their feet, they behaved as if they had received the shock themselves. It is believed that this demonstration of observational fear in rodents could match some characteristics of affective empathy in humans.

“Fear is a key instinct, as predicting danger is key to survival. It is not acquired only by directly experiencing a dangerous event, but also by observing others in threatening circumstances,” explained Dr. Keum Sehoon, the first author of the study.

In the present study, the research team compared 18 strains of mice commonly used in laboratories, and found they had different responses in the observational fear test. In particular, one strain (129S1) was significantly more empathic than the others.

After sequencing their genomes, the scientists were able to pinpoint to a gene variant of neurexin 3 (Nrxn3), a protein that helps to connect neurons, evolutionary conserved among vertebrates, and abundant in the cortex of the brain. Moreover, when the scientists artificially introduced the variant in mice with a normal level of empathic fear, the rodents’ behavior in the test changed noticeably as they became more empathic.

The researchers noted that specific neurons in a region of the cerebral cortex, known as anterior cingulate cortex (ACC), played a key role in the observational fear. The ACC has already been implicated in fundamental cognitive processes, including affective emotion, social cognition, and empathic response of pain and fear in mice and humans.

“This is the first report identifying a gene variant and associated neurophysiological mechanisms that control empathy-related neural circuits at a cellular and molecular level,” said Keum. “Studying genetic determinants of empathy will hopefully provide novel targets for therapeutic intervention in mental disorders.”

The article can be found at: Keum et al. (2018) A Missense Variant at the Nrxn3 Locus Enhances Empathy Fear in the Mouse.


Source: Institute for Basic Science; Photo: Pixabay.
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