Live Lecture: Hormones and Behavior

Testosterone: hypothalamus - pituitary - gonads (HPG) axis:
→ Testosterone drives dominance behavior in a highly dynamic manner.

Challenge hypothesis:
- High testosterone for competition and challenge
- Low testosterone for parental care and social bonding

Testosterone works recursively: it can build up, and it can decline.
→ It motivates us to go into competition with others, and by going into competition, the testosterone goes up too. So it motivates, but it also goes up by the motivation itself.
→ But if you lose these competitions, the testosterone will go down, and the motivation will decline as well.

Cortisol: hypothalamus - pituitary - adrenal glands (HPA) axis
→ Cortisol is produced in response to stress (reactive threat system: amygdala - hypothalamus - autonomous nervous system)
Cortisol is an end product! → High cortisol is not the cause of stress but the result of stress.
→ Serves a homeostasis function.
→ Can also build up (promotes threat anticipation): it will help to focus your attention on stressors more strongly.
- When this happens, you can reach an excess point of cortisol = allostatic load (when cortisol is overloaded, you won’t be able to reach a point of homeostasis anymore, chronic overload of cortisol).
- Related to different types of diseases, like obesity, cardiovascular diseases, hypertension, etc.

Cortisol (HPA) versus testosterone (HPG): the HPA axis inhibits the HPG axis and thus testosterone production, on all its levels, and cortisol also inhibits the action of testosterone in the brain.
→ This balance helps explain how testosterone can contribute to dominance behaviors.
- For example, when testosterone is high, when in competition, it can inhibit cortisol. And also the other way around.
- The inhibition is not perfect; both hormones can be high or low at the same time as well.

Testosterone and social hierarchy:
- Social hierarchy favors the individual (higher individuals have, for example, more power, food, sex, more chance of surviving).
- It also favors the group (makes the group stronger, more food, in war situations they are stronger, etc.)
Hierarchy dynamics:
- Social aggression: forms and maintains social hierarchy
- Physical violence: causes damage or is symbolic (fight without harm)
- Displays of dominance:
  → Physical displays (without physical contact)
    - Like having gorilla groups, the upper gorilla is dominant, shows that in his behavior (eye contact, for example).
  → Cultural displays
    - Things like clothing in humans
  → Signaling behavior:
    - Staring contest

Eye contact/staring contest:
- Social confrontation: prevents aggression (like a referee looking at a footballer in the eyes with a severe gaze, to make clear he must not show that kind of behavior again).
- Gaze aversion is a subordinate gesture

The (classical/emotional) stroop task compared to eye contact/gaze aversion studies:
→ They used a pictorial emotional stroop task (interference of expression)
→ After seeing the face, you have to name the color of it.
The idea is that the expression of the face will interfere with your cognitive ability to name the color. They measured the differences in reaction time between neutral and angry faces or angry versus happy faces.
→ So higher scores mean more interference from the particular expression
Results show that with higher testosterone levels there is more interference with naming the color.
But, higher levels of cortisol (so more stressed) show less interference, so a faster response at angry faces.

In a follow-up study, they looked at levels of social anxiety disorders.
→ The people with higher levels of SAD show a facilitation of response to angry faces.

Nonhuman primate (neuro-evolutionary) models of SAD, three important factors:
1. Variable foraging demand (early environmental stress)
2. Attachment (lack of mother-child bonding)
3. Low in the social hierarchy: subordinate stress (cost of submissiveness)

Testosterone (cortisol) and SAD:
- Cortisol levels are high in all anxiety-related disorders.
- Social anxiety disorder is particularly associated with low testosterone.

From this, the idea came that this stroop effect might have something to do with the staring contest: because if you are dominant and confronted with an angry face, you will have the motivation or automatic reaction to maintain eye contact, because that is what you do as a dominant person. And this will slow you down in color naming.
However, when you are fearful of the angry face, your testosterone is low and cortisol is high, then you will want to have that face away and thus react rapidly and react faster to name the color of the face.
→ So a new experiment was done with tracking the eye gaze to the correct color of the face.
→ Positive correlation score with dominance
→ In a placebo-controlled testosterone administration: there is a strong anger interference score in the testosterone group. Because they are more dominant, so hold contact with the angry face a little longer.
→ In a selection of SAD patients: there was a strong effect of the high SAD group, who very rapidly gazed away from the angry faces and thus had a faster response.
- Finally, they tried to treat the people with SAD, with testosterone
→ This showed that although they have SAD, with the testosterone, they become dominant as well and longer keep contact with the angry face, and thus have a slower reaction compared without testosterone.

This research shows that testosterone could be used as a treatment for people with SAD.
- But it must be limited to a few weeks; otherwise, the physical effects will show.
- And it’s best to combine it with cognitive-behavioral therapy

Social hierarchy and Testosterone/Cortisol ratio:
- In gorillas, the T/C ratio predicts hierarchy position (high testosterone, low cortisol)
→ They also use intimidation, instead of fighting for dominance
- But in baboons: the alpha male has high testosterone, but also high cortisol
→ In baboons, there is a constant fight for dominance. So there is always a threat for the alpha male. Therefore, the cortisol levels are high in the alpha male of baboons.
→ But when the alpha male uses, or can use intimidation, the cortisol is low and testosterone is high.

In humans, it is hard to replicate this effect because:
- We have a lot of different hierarchies in different groups.
- Violence is not tolerated (pathology)
→ But there are exceptions, for example: prisons, war. It is confirmed here, that the people higher in the hierarchy indeed have higher levels of testosterone, and lower levels of cortisol.

What does this do on brain level: neural circuitry of T/C aggression:
→ Testosterone:
- Decouples OFC from amygdala (multiple mechanisms): reduces the communication between the regular system and the reactive system, so there is less control over this threat system, resulting in a more reactive form of behavior when confronted with a threat.
- Promotes central amygdala (CMA) vasopressin gene expression, biasing the CMA’s (reactive system) effect on threat reactivity towards fight (instead of flight).
→ So on two levels, testosterone helps you to go into competition and not being