Mesolimbic Circuitry Flashcards
How did James Olds study the “pleasure centers” of the brain with mice in the 1950s? What did he find?
Electrode in mouse’s brain- when mouse would press bar, it would receive an electrical impulse
Electrode in “pleasure center”- mouse would press bar at very high rates
What unethical experiments did Heath (psychiatrist) perform to measure the “pleasure centers” of the brain in people? Were his results similar or dissimilar to Olds’?
Stimulated “pleasure centers” of prisoners’ brains with electrodes
Similar
In Olds’ and Heath’s studies, what was the name of the brain path being stimulated?
Medial forebrain bundle
The medial forebrain bundle contains fibers that stretch from which region of the brain to which other region?
Hindbrain to forebrain
What was the result in animals’ bar pressing behavior after their medial forebrain bundles were severed?
Bar pressing went down
Treatment with what neurotoxin had a similar effect to severing the medial forebrain bundle? What was this behavioral effect?
6-hydroxydopamine
Reduction in bar pressing
Mogenson proposed that addiction circuits in the brain connected the ____ system with the parts of the brain that control ____.
Motor
Motivation
Mogenson’s modern day addiction circuitry:
1) Inputs from the ___ system and ____
2) Central part: ___ ___ ___ projects to the ___ ___
3) Outputs to the ___ systems
1) Limbic Cortex 2) Ventral tegmental area Nucleus accumbens 3) Motor
Exposing brain sections to ____ vapors made ____ (neurotransmitter type) fluoresce. How were the neuronal clusters numbered based on their wavelength of fluorescence?
Aldehyde
Monoamines
A or B
The “A” fluorescent pathways were linked to the presence of ____ (neurotransmitter type), whereas the “B” fluorescent pathways were linked to the presence of ____ (neurotransmitter).
Catecholamines
Serotonin
In the fluorescence experiments, what 2 catecholamines were linked to the “A” green/yellow fluorescence?
Dopamine
Norepinephrine
The “A” catecholamine fluorescence pathway was deemed to be a primary component of the ___ ____ ___ (the “pleasure centers” from older experiments).
Medial forebrain bundle
The addiction circuit of today still focuses on the ___ system, the ___ ____ ___, the __ ___, and the ___ ___ ___.
Limbic system
Ventral tegmental area
Nucleus accumbens
Medial prefrontal cortex
Projections and neurotransmitters released:
1) The ventral tegmental area projects to what two other areas and releases what neurotransmitter?
2) The medial prefrontal cortex projects back to what other area and releases what neurotransmitter?
3) The nucleus accumbens projects back to what other area and releases what neurotransmitter?
4) The nucleus accumbens also receive inputs from what other two areas, and what neurotransmitter is released from these inputs?
1) Medial prefrontal cortex, nucleus accumbens Dopamine 2) Nucleus accumbens Glutamate 3) Ventral tegmental area GABA 4) Ventral hippocampus, amygdala Glutamate
The ventral tegmental area is located on the ventral surface of the ____, just medial to the ___ ___. What is the designation for this cell group (think back to the fluorescence groups), and what neurotransmitter is synthesized here?
Midbrain
Substantia nigra
A10
Dopamine
3 forebrain pathways from the ventral tegmental area:
1) ____ (VTA to ___ system)
2) _____ (VTA to ____)
3) _____ (VTA to both ___ and ____ system)
1) Mesolimbic Limbic 2) Mesocortical Cortex 3) Mesocorticolimbic Cortex and limbic
The nucleus accumbens has what 2 subdivisions? How are they similar in terms of input and how are they different in terms of output?
Core
Shell
Both have input from VTA
Different output targets
The nucleus accumbens shell is associated with what region and has functions related to what?
Limbic system
Reward and aversion
The nucleus accumbens core is associated with what region and links what two functions?
Motor systems
Motivation and action
The nucleus accumbens also receives inputs from what 3 other brain regions?
Amygdala
Hippocampus
Thalamus
Dopmaine circuit study:
1) Either norepinephrine or dopamine pathways were damaged with what neurotoxin?
2) Depletion of which neurotransmitter had the greatest effect on cocaine self-administration? What was that effect?
1) 6-hydroxydopamine
2) Dopamine
Decrease in self-administration
Study that sought to cure addiction in humans by damaging dopamine pathway:
1) Was addiction “cured?”
2) What was the side effect?
3) Is damaging the dopamine pathway a viable treatment for addiction?
1) Yes
2) Subjects lost motivation for other activities in addition to drug taking
3) No
All drugs of abuse have pathways that converge on which of 2 possible brain structures?
Ventral tegmental area
Nucleus accumbens
How does the common anatomical pathway of addiction support the DSM IV model of substance abuse?
Diagnosis of substance abuse is substance-independent
