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60 free Dopamine trivia questions with answers — science & nature quiz, new questions added Aug 2026.
Dopamine is the most talked-about molecule in the brain and the most misunderstood, and this trivia quiz sets the record straight. It covers the chemistry (which amino acid it comes from, which enzymes make and destroy it, why it cannot cross the blood-brain barrier), the anatomy (the substantia nigra, the ventral tegmental area, the mesolimbic pathway and the surprisingly small number of neurons involved) and the science of reward, from Olds and Milner's lever-pressing rats to Wolfram Schultz's reward prediction error and the difference between wanting and liking. It also covers the medicine and the history: Parkinson's disease and L-DOPA, the dopamine hypothesis of schizophrenia, how cocaine and Ritalin work, why dopamine stops nausea and milk production, the 1910 synthesis in London, Kathleen Montagu's 1957 discovery of dopamine in the human brain and Arvid Carlsson's Nobel Prize. There are lighter questions too: which fruit is richest in dopamine, what an octopus's ink contains and what "dopamine fasting" actually means. Every answer was verified against Wikipedia's articles on dopamine, the reward system and related topics, and each question links to its source. Try our Human Brain and Nicotine quizzes next.
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Q 01Dopamine is made from its precursor L-DOPA by removing what?
A carboxyl group
The step is called decarboxylation and is done by the enzyme DOPA decarboxylase.
Q 02Rather than pleasure itself, mainstream pharmacology holds that dopamine signals what?
Motivational salience
In other words it flags how desirable or aversive an outcome is and drives behaviour toward or away from it.
Q 03To which chemical family, along with norepinephrine and epinephrine, does dopamine belong?
Catecholamines
It is the simplest possible catecholamine: a benzene ring with two hydroxyl groups and an amine on an ethyl chain.
Q 04The primary synthesis pathway for dopamine starts with which essential amino acid?
Phenylalanine
Phenylalanine becomes tyrosine, tyrosine becomes L-DOPA and L-DOPA becomes dopamine.
Q 05Which enzyme carries out the rate-limiting step of dopamine synthesis, turning an amino acid into L-DOPA?
Tyrosine hydroxylase
It needs tetrahydrobiopterin, oxygen and iron as cofactors.
Q 06Besides oxygen, which vitamin-derived cofactor does dopamine beta-hydroxylase need?
Ascorbic acid
Norepinephrine is then converted to epinephrine using S-adenosyl-L-methionine.
Q 07What is the main inactive end product of dopamine breakdown, excreted in urine?
Homovanillic acid
Its plasma levels have been used in schizophrenia research as a proxy for brain dopamine activity.
Q 08Which two enzymes, along with aldehyde dehydrogenase, break dopamine down?
Monoamine oxidase and COMT
Both MAO-A and MAO-B metabolise dopamine effectively.
Q 09How many subtypes of dopamine receptor have been identified in mammals?
Five
They split into D1-like and D2-like families, all of them G protein-coupled.
Q 10Which dopamine receptor is the most numerous in the human nervous system?
D1
D2 comes next; D3, D4 and D5 are present at much lower levels.
Q 11Roughly how many dopamine-producing neurons does the human brain contain?
About 400,000
Their cell bodies sit in a few small areas, but their axons reach much of the brain.
Q 12Which transporter packs dopamine into synaptic vesicles for storage?
VMAT2
After release and reuptake, dopamine is either repackaged by VMAT2 or broken down by monoamine oxidase.
Q 13Which two Swedish scientists first mapped the brain's dopamine cell groups (A8 to A14) in 1964?
Dahlström and Fuxe
Groups A1 to A7 in their scheme contain norepinephrine instead.
Q 21Robinson and Berridge's 1993 incentive-sensitization theory split reward into which two components?
Wanting and liking
Dopamine drives the wanting; the liking lives in separate hedonic hotspots.
Q 22Cambridge neuroscientist Wolfram Schultz discovered that dopamine neurons signal what?
Errors in reward prediction
He found it recording from macaque monkeys in the 1980s and 1990s.
Q 23Why is L-DOPA given to Parkinson's patients instead of the neurotransmitter itself?
It cannot cross the blood-brain barrier
Q 14The substantia nigra, whose dopamine neurons die in Parkinson's, sits in which part of the brain?
The midbrain
Its name is Latin for "black substance".
Q 15What gives the substantia nigra its dark colour?
Neuromelanin
There is evidence that this pigment is at least partly dopamine-melanin.
Q 16The dopamine projection from the substantia nigra to the dorsal striatum is called what?
The nigrostriatal pathway
When enough of these neurons die, the result is a parkinsonian syndrome.
Q 17Which projection carries dopamine from the ventral tegmental area to the nucleus accumbens?
The mesolimbic pathway
Together with the mesocortical projection to the prefrontal cortex it forms the mesocorticolimbic system.
Q 18Dopamine from the hypothalamus is the main inhibitor of which pituitary hormone?
Prolactin
Without dopamine the pituitary's lactotroph cells secrete it continuously.
Q 19Dopamine-releasing amacrine cells in the retina are active when?
During daylight hours
They boost cone cells and suppress rods, sharpening colour and contrast in bright light.
Q 20Which two researchers accidentally discovered brain-stimulation reward in rats in 1954?
James Olds and Peter Milner
Rats would press a lever hundreds or thousands of times an hour to zap their own brains.
It is usually paired with carbidopa or benserazide to stop it being converted before it reaches the brain.
Q 24L-DOPA was first isolated in 1913 from the seeds of which plant?
The broad bean
Swiss biochemist Markus Guggenheim did it; velvet beans of the genus Mucuna are an even richer source.
Q 25Which Vienna-based scientist found that Parkinson's disease stems from a dopamine deficiency?
Oleh Hornykiewicz
He shared the 1979 Wolf Prize with Carlsson and Roger Sperry for opening the L-DOPA approach.
Q 26Oliver Sacks's memoir Awakenings, filmed in 1990, describes giving L-DOPA to survivors of which epidemic?
Encephalitis lethargica
Robin Williams played the Sacks-based doctor and Robert De Niro the patient Leonard Lowe.
Q 27Which misfolded protein clumps into Lewy bodies in Parkinson's disease?
Alpha-synuclein
Because of it, Parkinson's is classed as a synucleinopathy.
Q 28Long-term dopaminergic Parkinson's treatment can cause compulsive gambling and sex in a condition called what?
Dopamine dysregulation syndrome
It involves overuse of the medication as well as compulsive pursuit of natural rewards.
Q 29Cocaine and methylphenidate raise synaptic levels of the neurotransmitter mainly by doing what?
Blocking the dopamine transporter
Amphetamines also raise synaptic dopamine but by different mechanisms.
Q 30How long do the effects of cocaine typically last?
5 to 90 minutes
That rapid, brief action is a big part of why it is so addictive; pill-form methylphenidate can last 12 hours.