Dopamine Neurotransmission

Question 1

How is dopamine synthesised and broken down?

Answer 1

Tyrosine > Tyrosine Hydroxylase > DOPA > DOPA decarboxylase > Dopamine > Dopamine Beta Hydroxylase > Noradrenalin > Phenylethanolamine N methyl-transferase > Adrenalin

Question 2

What are the four key dopamine pathways and their function?

Answer 2

Nigrostriatal - affects motor function (implicated in Parkinson’s)
Mesolimbic - Ventral tegmental area > nucleus accumbens, reward learning
Mesocortical - Ventral tegmental area > Dorsolateral and ventromedial prefrontal (implicated in reward anticipation and consumption)
Tuberoinfundibular - Hypothalamus > anterior pituitary, prolactin secretion (frequent dopamine prevents prolactin release)

Question 3

The primary reinforcer has…

Answer 3

direct benefit to survival

Question 4

The secondary reinforcer has….

Answer 4

no value, but enables access to the primary reinforcer

Question 5

Explain dopaminergic neuron firing in reward.

Answer 5

Dopamine neurone fire in the ventral tegmental area in response to reward. After conditioning, action potentials fire in response to presentation of the predictor, but in the absence of reward there is decreased firing.