dopamine

(noun)

A neurotransmitter associated with movement, attention, learning, and the brain's pleasure and reward system.

Related Terms

  • narcotic
  • delusion
  • narcolepsy
  • bipolar disorder
  • ADHD
  • hallucination
  • schizophrenia
  • neurotransmitters
  • serotonin
  • neurotransmitter

Examples of dopamine in the following topics:

  • Neurotransmitters

    • Dopamine is the best-known neurotransmitter of the catecholamine group.
    • The brain includes several distinct dopamine systems, one of which plays a major role in reward-motivated behavior.
    • Most types of reward increase the level of dopamine in the brain, and a variety of addictive drugs increase dopamine neuronal activity.
    • Other brain dopamine systems are involved in motor control and in controlling the release of several other important hormones.
    • On the other hand, when an excess of the neurotransmitter dopamine blocks glutamate receptors, disorders like schizophrenia can occur.
  • Types of Neurotransmitters by Function

    • Biogenic amines include the catecholamines, such as dopamine, norepinephrine (NE), and epinephrine, as well as indolamines such as serotonin and histamine.
    • Dopamine and NE are synthesized from amino acid tyrosine.
    • NE, dopamine, and histamine can be excitatory or inhibitory depending on the receptor type.
    • Addictive drugs such as cocaine and amphetamine exert their effects primarily on the dopamine system, while addictive opiates and functional analogs of opioid peptides which regulate dopamine levels.
  • Etiology of Schizophrenia

    • The dopamine hypothesis of schizophrenia is a model used by scientists to explain many schizophrenic symptoms.
    • The model claims that a high fluctuation of levels of dopamine can be responsible for schizophrenic symptoms.
    • The dopamine hypothesis has helped progress the development of antipsychotics, which are drugs that stabilize positive symptoms by blocking dopamine receptors.
    • The fact that these medications have been shown to treat psychosis supports the dopamine theory.
    • Dopamine is not the only neurotransmitter associated with schizophrenia, although it can be argued that it is the most studied.
  • Stimulants

    • Some stimulants facilitate the activity of certain neurotransmitters, specifically norepinephrine and/or dopamine.
    • Over time, stimulants can disrupt the functioning of the brain's dopamine system, dampening users' ability to feel any pleasure at all.
    • MDMA differs from most stimulants in that its primary pharmacological effect is on the neurotransmitter serotonin rather than dopamine, epinephrine, or norepinephrine.
    • MDMA also decreases the release of dopamine.
    • Norepinephrine and dopamine reuptake inhibitors (NDRIs) (such as the antidepressant Wellbutrin) inhibit the uptake of dopamine and norepinephrine, effectively increasing their amounts in the brain and causing a stimulating effect.
  • Neurodevelopmental Disorders: Mental Illnesses

    • Treatment for the disease usually requires anti-psychotic medications that work by blocking dopamine receptors and decreasing dopamine neurotransmission in the brain.
    • This decrease in dopamine can cause Parkinson's disease-like symptoms in some patients.
    • For example, dopamine may also be decreased in depressed patients, or it may actually be an increase in norepinephrine and serotonin that causes the disease, and antidepressants force a feedback loop that decreases this release.
    • For example, monoamine oxidase inhibitors (MAO inhibitors) block the enzyme that degrades many neurotransmitters (including dopamine, serotonin, norepinephrine), resulting in increased neurotransmitter in the synaptic cleft.
    • Other types of drugs, such as norepinephrine-dopamine reuptake inhibitors and norepinephrine-serotonin reuptake inhibitors, are also used to treat depression.
  • Arousal Theory of Motivation

    • While drive-reduction theory focuses primarily on biological needs as motivators, arousal theory examines the influence of the neural transmitter dopamine as a motivator in the body.
    • Reward sensitivity is located in the mesolimbic dopamine system.
    • For example, substance use is associated with overactivity in the dopamine system; depending on how strongly an individual's brain interprets that as a "reward," they may be more or less motivated to continue using that substance.
    • This study provided evidence that animals are motivated to perform behaviors that stimulate dopamine release in the reward center of the brain.
    • Dopamine pathways in the brain play an important role in the regulation of reward, which, in turn, motivates behavior.
  • How Emotion and Mood Influence Behavior

    • Emotions can be influenced by hormones and neurotransmitters, such as dopamine and seratonin.
    • Dopamine can affect a person's energy level and mood, while seratonin can affect critical-thinking skills.
    • An active lifestyle has been shown to produce an increased level of dopamine, which can enhance energy and mood.
  • Epinephrine and Norepinephrine

    • It is the hormone and neurotransmitter most responsible for vigilant concentration in contrast to its most-chemically-similar hormone, dopamine, which is most responsible for cognitive alertness.
    • Norepinephrine is synthesized from dopamine by dopamine β-hydroxylase in the secretory granules of the medullary chromaffin cells and is released from the adrenal medulla into the blood as a hormone.
  • Neurodegenerative Disorders

    • Parkinson's disease causes the loss of dopamine neurons in the substantia nigra, a midbrain structure that regulates movement.
    • One of the most-commonly prescribed drugs for Parkinson's is L-DOPA, which is a chemical that is converted into dopamine by neurons in the brain.
    • This conversion increases the overall level of dopamine neurotransmission and can help compensate for the loss of dopaminergic neurons in the substantia nigra.
    • Other drugs work by inhibiting the enzyme that breaks down dopamine.
  • Cerebral Lobes

    • The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex.
    • The dopamine system is associated with reward, attention, short-term memory tasks, planning, and motivation.
    • Dopamine tends to limit and select sensory information that the thalamus sends to the forebrain.
    • A report from the National Institute of Mental Health indicates that a gene variant that reduces dopamine activity in the prefrontal cortex is related to poorer performance in that region during memory tasks; this gene variant is also related to slightly increased risk for schizophrenia.
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