Amygdala and it’s Relationship to Testosterone and Fear

The amygdala is the center of emotional activity in the brain, but recent studies have shown that it's powered by motivation rather than the emotions themselves.

This conclusion came from research into the hormone testosterone.

Testosterone ramps up amygdala activity when we approach a socially dangerous situation and lessens the activity when these situations are avoided.

It was a known fact that the amygdala reaction to images of angry faces was more intense in someone who had received testosterone.

This new study shows that this only happens when people approach angry faces and not when they avoid them.

Testosterone or Placebo

In a double-blind, placebo-controlled study, 54 young, healthy women were given 0.5 mg of testosterone (or a placebo) four hours before a brain scan.

This amount is a far lower dose than used for a sex change treatment, or as a supplement for athletes, but it is enough to have a measurable effect on brain activity.

Happy or Angry

While in the MRI-scanner, the participants were shown photos of happy and angry faces and were asked to give a sign of rejection (avoiding) or approach (moving towards).

People usually have less of a problem approaching someone who looks friendly and non-threatening than someone who seems angry.

Approaching an angry face requires considerably more effort and control.

The reaction times confirmed this as they were slower than when an angry face approached.

Meanwhile, the researchers measured amygdala activity.

The activity was higher in women who had been given testosterone only when they approached angry faces, and only then.

Amygdala and Motivation

"Previous research has shown that higher testosterone levels lead to an intensified amygdala reaction in the presence of angry faces," says Karin Roelofs, Professor of Experimental Psychopathology at the Donders Institute for Brain, Cognition, and Behaviour, Radboud University.

"Those earlier investigations looked at what happens in non-active situations and not during an action.

The focus was on what you should do if you see an angry face.

The theory is that testosterone assists social approach by explicitly activating the amygdala only if a social strategy is wanted.

There are two reasons why this is intriguing.

First, it explains previous research that concluded that testosterone makes approaching a social threat easier.

Second, and far more critical, it demonstrated that the amygdalae are not necessarily linked to emotions, but rather to motivation.

Most studies completely ignore motivation.

We are the first to show that the impact of testosterone on amygdala response depends on the motivational context."

What About Cases of Social Anxiety?

"We're now going to repeat this study in people with social anxieties.

We have already discovered that these people have lower testosterone levels.

We are going consider how we can apply these results with testosterone to improve the treatment of anxiety disorders" Dr. Roelofs concluded.

Reference

Endogenous testosterone is associated with lower amygdala reactivity to angry faces and reduced aggressive behavior in healthy young women.

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