Lecture 8 Flashcards
What are hormones?
Hormones are usually secreted by the endocrine system. They are released into the bloodstream and they act on distant target sites. They are thought to induce biological effects via a relatively slow mode of action.
What are neurotransmitters?
Neurotransmitters are synthesised by neurons and released in the presynaptic nerve terminal in the brain. They move across the synaptic cleft to the next neuron. Neurotransmitters work locally and their actions are very fast.
What are neurohormones?
Similar to neurotransmitters, neurohormones are released by neurons. Similar to hormones, they travel in the bloodstream. In short, a neurohormone is a hormone that is produced and released by neuroendocrine cells into the blood. They are chemical messenger molecules synthesised in neurons but enter the bloodstream which carries them to distant tissues.
What are the 3 ways of measuring oxytocin? What are the issues?
One can measure it via exogenous (intranasal) oxytocin administration. For oxytocin to reach the brain it would take a long time and not all blood reaches the brain. Therefore, there is no simple way to verify whether the substance reached the brain after administration.
It can also be measured through endogenous oxytocin plasma levels. Measurement of oxytocin levels in plasma is done by the use of oxytocin antibodies. But many oxytocin antibodies are also bound to other substances. Extraction is required but it is usually skipped.
Genetic polymorphisms of the oxytocin receptor gene is the third measurement type. Though, most published candidate gene studies are dramatically underpowered and are almost surely false positives.
What are the effects of oxytocin on trust?
Some studies argue that it has something to do with trusts, some do not. Though, what is certain is that it improves the accuracy of the trustworthiness judgement of others and it promotes social learning.
What are the effects of oxytocin in the case of testosterone-cortisol ratio?
Oxytocin has a negative effect on (restoration of) trustworthiness when testosterone-cortisol ratio is high.
What is the effect of testosterone on trust?
Testosterone is an antagonist and inhibitor of oxytocin. It inhibits trust but promotes reciprocity. In the context of social challenge, testosterone is associated with competitive, potentially antisocial behaviour. In the absence of social challenge, testosterone might even enhance prosocial behaviour, increased reciprocity.
What is the effect of cortisol on trust?
Some studies argue that acute stress both increases non-social gambling (take more risk) and diminished social trusting behaviour. Though, another study showed that results go in different directions. Higher baseline cortisol is correlated with greater trust.
What is the effect of vasopressin on trust?
Individuals with a long form of AVPR1 demonstrated lower levels of trust and lower levels of reciprocity
What is the effect of oestrogen on trust?
Though it had no significant effect on trust or trustworthiness, oestrogen facilitates oxytocin receptor binding and increases the number of oxytocin receptors.
What are the roles of dopamine?
Dopamine is the main neurotransmitter associated with reward processing. It connects areas within the reward network. In the dorsal striatum, it monitors outcomes of our actions to facilitate reward-based learning. In the ventral striatum it predicts whether reward will result from a future action.
