What happens in the brain when we see other people experiencing a trauma or being subjected to pain?
According to a new study, the same regions that are involved when we feel pain are also activated when we observe other people who appear to be going through some painful experience.
But we are sensitive to different degrees to learning fear from other people, according to researchers at the Karolinska Institutet in Sweden. They say one explanation for that may be found in the endogenous opioid system.
Seeing others express pain or anxiety can give us important information about things around us that are dangerous and should be avoided, the researchers noted.
Sometimes, however, we can develop fear of situations that, rationally speaking, are not dangerous.
While the opioid system is supposed to alleviate pain and fear, it does not work as effectively in all of us. This might be one of the reasons some people develop anxiety syndrome merely by seeing others experience a trauma, the researchers said.
“Some people are over-sensitive to this form of social learning,” said main author Dr. Jan Haaker, associated researcher at Karolinska Institutet’s Department of Clinical Neuroscience.
“Our study shows that the endogenous opioid system affects how sensitive we are and may explain why some people develop post-traumatic stress disorder (PTSD) merely by observing others who are experiencing traumatic events. After terror attacks, sensitive people might be afraid even if they themselves were not present.”
In a double-blind study, the researchers altered the brain’s internal chemistry in 22 healthy subjects by using a pharmaceutical substance to block the opioid system. Another 21 subjects were given an inactive placebo. The subjects then watched a video where other people were subjected to electric shocks.
The brain normally updates its knowledge of danger based on whether we are surprised, but when the opioid system was blocked, the people continued to react as if they were surprised even though they knew the electric shock would come, the researchers discovered.
The response was amplified even when they continued to watch other people being subjected to shocks.
The response increased in regions of the brain such as the amygdala, the periaqueductal gray and the thalamus, which seems to indicate that the same functions as in self-perceived pain were involved, the researchers said.
Communication also increased between these and other regions of the brain that are linked to the ability to understand other individuals’ experiences and thoughts.
“When the people participating in the experiment were themselves subjected to threatening stimuli that they had previously associated with other people’s pain, they perspired more and displayed more fear than those who had been given a placebo,” said research team leader Dr. Andreas Olsson, senior lecturer at the institutet’s Department of Clinical Neuroscience.
“This enhanced learning was even visible three days after the social learning episode.”
The researchers said they hope the new findings will eventually mean that people with anxiety conditions will be able to be given better, more individual-adapted clinical help.
The study was published in Nature Communications.
Source: Karolinska Institutet