Ruhr University Bochum in Germany is finding a way to make people fearless. Their research was a result of the fear and anxiety resulting from Post-traumatic stress disorder (PTSD). This disorder requires the people suffering from it to make a substantial effort to overcome it.
PTDS is a result of people going through traumatic events. The disease is often debilitating as patients could experience anxiety leading to a traumatic mental state. Researchers are now hoping to improve extinction learning which decreases the manifestation of behavior due to external stimuli.
Serotonin influences anxiety and fear. For this reason, the scientists focused their study on the hormone. They genetically engineered mice that lacked 5-H2TC, a serotonin receptor, and taught them to link a certain sound to a negative stimulus.
Katharina Spoida, a study co-author, states that the mice demonstrated a fear response where they would pause in response to the sound. They called this response freezing. Afterward, the scientists would play the sound without introducing the unpleasant stimuli. They found that the mice without the 5-H2TC receptors learned faster to dissociate the tone from the trigger. Spoida says this shows how lacking the receptor is advantageous in extinction learning.
The team conducted more studies to evaluate their findings. It realized that mice have neuronal changes in two areas. These were the basal nucleus of the stria terminalis (BNST) and the dorsal raphe nucleus (DRN). The DRN produces serotonin, while the BNST, a component of the amygdala, does emotional processing after stimuli.
Sandra SÜB, another study author, adds that the researchers initially found high activity along cells of the DRN that produce serotonin. They later realized that removing the receptor caused less sensitivity in two BNST subnuclei, thus improving extinction learning.
The scientists concluded that the results meant there was a relationship between the nuclei which play a role in extinction learning. Furthermore, the study could help scientists understand how selective serotonin reuptake inhibitors affect these two regions as antidepressants.
SüB suggests that these drugs could make serotonin receptors less sensitive to stimulation leading to the same effect as the mice with no serotonin receptors.