Andrew Fox began by exposing 46 young rhesus macaques to the typical terrifying situation where a human enters their cage without making eye contact with the animals.
The interactions of different monkeys were evaluated and then the researcher used a number of biomolecular methods to identify genes whose activity in the amygdala could be linked to the interaction of monkeys.
One of these genes was NTF3, which encodes a specific signaling molecule. The more active the gene is in the amygdala of the monkey, the greater the monkey’s tendency to calm in the feared situation.
Andrew Fox inserted the gene into a harmless virus and injected it into the tonsils of five out of ten monkeys, which in the first test showed a uniformly moderate fear.
The procedure is similar to that used in experimental DNA or RNA vaccines against, for example, covid-19.
In this case, the theory behind the experiment was that the virus would infect nerve cells in the amygdala and cause them to produce large amounts of the signaling molecule, just as in monkeys that were less fearful on the first test.
When humans visited the five vaccinated monkeys and avoided eye contact, they were significantly less afraid than the other five unvaccinated monkeys.
Andrew Fox and colleagues don’t know exactly how the NTF3 gene keeps fear at bay, but they hypothesize that the signaling molecule stimulates the formation of a network of neurons that suppress the activity of the amygdala.
Researchers will now investigate this in more detail. They expect the method to be the start of a completely new way to treat and prevent anxiety in humans.
“NTF3 is the first molecule that we have been able to demonstrate its association with fear in monkeys. There could be hundreds or even thousands of these,” says Andrew Fox.