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Year 1: 07. Neuro Exam 3 > Lecture 7: Neurophysiology of Reward and Addiction > Flashcards

Lecture 7: Neurophysiology of Reward and Addiction Flashcards

1
Q

What is motivation?

A

A process that mediates goal-directed responses or goal-seeking behavior to changes in the external or internal environment

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2
Q

What is saliency?

A

Something important in the surrounding env. worth paying attention to

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3
Q

What is a reward?

A

Objects, stimuli, or activities that have positive value

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4
Q

What is aversion?

A

A negative reinforcement of behavior that the individual will learn to avoid future encounters

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5
Q

What is pleasure?

A

A positive sensation

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6
Q

What is the purpose of pleasure?

A

Promote behaviors that are consistent with survival of self and the species

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7
Q

What NT plays a role in pleasure reward seeking behavior?

A

Dopamine

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8
Q

How do drugs affect dopamine concentration?

A

Will increase extracellular concentration of dopamine in limbic areas and prevent reuptake of dopamine

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9
Q

What is a salience stimuli?

A

A noticeable stimuli that can be arousing or elicits a behavioral switch

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10
Q

Why are addicts at a great risk for relapse when they visit places they had taken drugs at?

A

The stimuli around them are salient (noticeable)

The stimuli itself can increase dopamine and elicit desire for drugs.

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11
Q

Briefly, how does the mesolimbic system work?

A

Dopamine is produced in VTA

VTA dopaminergic fibers are projected to nucleus accumbens.

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12
Q

What is the main function of the nucleus accumbens?

A

Suppress sensations of pleasure and reward

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13
Q

What structures constitutively activate (via EAA like glutamate) nucleus accumbens?

A

Hippocampus
Amygdala
Prefrontal cortex (PFC)

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14
Q

What type of neurons does the nucleus accumbens release?

A

GABA (inhibitory)

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15
Q

What pathway occurs when you do something that elicits a reward?

A
  1. Dopamine neurons synthesized in VTA project to nucleus accumbens.
  2. Dopamine released into NA, inhibits it.
  3. NA activity decreases, resulting in a sensation of pleasure
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16
Q

What stimulates the VTA when you engage in behavior or activity that results in rewards?

A

Pre-frontal cortex: EAA
Tegmental nuclei: ACh
Hypothalamus: Orexin (from food)

17
Q

What suppresses the VTA?

A
  1. Nucleus Accumbens: GABA

2. Nucleus Accumbens: Dynorphin (transmitter)

18
Q

What is the dopamine-hypothesis reward?

A

Inactivation of nucleus accumbens via dopamine from VTA

19
Q

What activities can increase endogenous opioid signaling?

A

Exercise
Ethanol
Other stuff

20
Q

What receptors do opioid signaling utilize to activate dopaminergic receptors at VTA?

A

Mu receptors

21
Q

How does opioid signaling work?

A
  1. Inhibit local VTA interneurons that normally suppress dopaminergic neurons in VTA
  2. Disinhibit dopaminergic neurons
  3. Activate nucleus accumbens local interneurons to inhibit the release of GABA
  4. Activate pre-frontal cortex
22
Q

What is the result of endogenous opioid signaling?

A

Pleasure

Euphoria

23
Q

From a neurobiological perspective, what does addiction probably result from?

A

Recurrent supraphysiologic perturbations in dopamine system

Chronic drug exposure alters the morphology of neurons in dopamine-regulated circuits

24
Q

How can drugs change things at a cellular level?

A

Alter expression of certain transcription factors and proteins involved in neurotransmission in brain regions regulated by dopamine

25
Q

How can drugs change things at a neurotransmitter level?

A

Abnormal NT levels for dopamine, glutamate, GABA, opioids, serotonin

26
Q

Where are lasting memories of the good feelings associated with drugs created?

A

Memories made in hippocampus

27
Q

What structure mediates craving?

A

Amygdala

28
Q

When the abuser seeks out drugs, what structure is involved in the poor decision making?

A

Orbitofrontal cortex

29
Q

How does the activation of calcium-calmodulin-CREB mechanism work?

A

Promotes production of dynorphin in nucleus accumbens to shut off VTA and dopaminergic signaling

30
Q

What is physical dependency?

A

Chronic use of a tolerance-forming drug, in which abrupt or gradual drug withdrawal causes unpleasant physical symptoms

31
Q

Why does physical dependency occur?

A

Excessive noradrenergic output from the locus ceruleus (involved in arousal and vigilance)
CREB dependent up-regulation of target genes in locus ceruleus.

32
Q

When are the FosB and AP-1 genes up-regulated?

A

Stress

Drugs of Abuse

33
Q

How do natural reinforcers (food, sex, exercise) differ from drugs?

A

Natural Reinforcers: Firing of neurons stop when event concludes
Drugs: Dopamine release continues after activity

34
Q

How does dopamine change the reward circuitry?

A

Dopamine can alter a fearful stimuli to a pleasurable one

Ex: Before hearing a bell could be scary, but now hearing a bell is associated with euphoria from drugs

35
Q

How do addicted brains differ from non-addicted brains?

A

Conditioned cues reinforce saliency of substances, increasing behavior to find and consume drugs.
These cues override prefrontal cortex’s control of behavior

36
Q

What role does the substantia nigra and dorsal striatum play in pleasure/reward-seeking behavior?

A

Control motor response associated with navigating the environment for desirable activity

37
Q

What are differences between conditioned responses and drug-associated cues?

A

Conditioned responses: cues to drug-taking in specific social circumstances
Drug-associated cues: powerful cues that can elicit drug urges and physiologic responses w/o taking drug

38
Q

What role does the locus ceruleus play?

A

Involved with physiological responses to stress and panic

Synthesis of norepinephrine

39
Q

What does CREB mediate in the locus ceruleus?

A

Physical dependency due to excessive noradrenergic output from locus ceruleus

Year 1: 07. Neuro Exam 3 (16 decks)

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