The nucleus accumbens is located in the basal ganglia and is involved in motivation, reward, pleasure, and addiction. Three key studies are summarized: James Olds and Peter Milner in the 1950s found that rats would compulsively press a lever to stimulate their nucleus accumbens with electricity, even to the point of starvation. A 2007 study used deep brain stimulation of the nucleus accumbens to treat severely depressed patients, finding short-term improvements in mood and motivation but no lasting effects. Axmacher's 2010 study used EEG to find that the nucleus accumbens and hippocampus activate in response to surprising events, indicating its role in memory formation and responding to both pleasurable and aversive experiences.

1. Nucleus Accumbens
Pleasure Center of the Brain
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2. Location in the brain:
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3. Functions:
•Motivation and Reward
•Addiction
•Laughter
•Pleasure
•Fear
•Placebo Effect
Works on: Dopamine and Serotonin
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4. Three Studies:
James Oldes and Peter Milner (1950s)
Schaepfer, Sackeim, Luber et al. (2007)
Nikolai Axmacher (2010)
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5. Oldes & Milner (1950s)
Aim: Determine how rats would respond to the
opportunity of stimulating their pleasure centers
by pushing a lever.
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6. Oldes & Milner (1950s)
Procedure:
•Implanted electrodes
into the rats.
•Each time they pressed
the lever, they would
receive an electric
shock to their nucleus
accumbens.
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7. Oldes & Milner (1950s)
Results + Findings:
•The rats became addicted with pressing the lever.
•They preferred pressing the lever to eating or
drinking -- Many starved themselves.
•They ran across the electrified grid to reach the lever.
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8. Sackeim, Luber et al. (2007)
Aim: Treat severely depressed patients who
have not responded to treatment, with deep
brain stimulation.
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9. Sackeim, Luber et al. (2007)
Procedure:
•Implanted electrodes
into the nucleus
accumbens of the
depressed patients.
•Turned on the
stimulator, which sent
electrical signals to the
pleasure centers.
•Turned the stimulator
on and off over a
period of a few weeks.
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10. Sackeim, Luber et al. (2007)
Results and Findings:
•Most results showed that it was effective short
term, but not long term.
•It produced short term pleasure, instant
gratification that did not last.
•Did not treat long term depression
•Some patients found more motivation right after
the stimulation.
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11. Axmacher (2010)
Aim: The relation between the nucleus accumbens
and the formation of surprising events
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12. Axmacher (2010)
Procedure:
•Implanted electrodes in
the nucleus accumbens
and the hippocampus.
•Showed participants
various images
•ie. Face on red
background and house
on green background
•Used EEG to see brain
patterns
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13. Axmacher (2010)
Results + Findings:
•Switching the images activated the two different
areas of the brain
•The hippocampus, to the nucleus accumbens,
back to the hippocampus.
•Allows prediction of memory formation.
•The pleasure centers do not only activate
‘pleasurable’ memories, but also responds to bad
experiences.
•Something scary can release dopamine.
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14. Dysfunctions
•Depression
•Drug Addiction
•Tourette Syndrome
•ADHD
•Impulsive Choice
•Lack of Motivation
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15. Depression
•NAc role in pathophysiology of
depression
•Hypothesized that adhedonia produced
from NAc dysfunction
•Stress, Drugs produce depressive
phenotype->
•Change functions in NAc->
•Inhibited Dopaminergic activity in NAc
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16. Work Cited
Hanson, Dirk. "Addiction Inbox: The Nucleus Accumbens." Addiction Inbox. N.p., n.d. Web. 18
Oct. 2013. <http://addiction-dirkh.blogspot.com/2010/02/nucleus-accumbens.html>.
"How does the reward center in the brain work? - Curiosity." Curiosity : Discovery Channel. N.p.,
n.d. Web. 16 Oct. 2013. <http://curiosity.discovery.com/question/reward-center-in-brain-work>.
"NIMH · Brain Stimulation Therapies."NIMH · Home. N.p., n.d. Web. 17 Oct. 2013. <http://
www.nimh.nih.gov/health/topics/brain-stimulation-therapies/brain-stimulationtherapies.shtml#Lisanby>.
"Science Daily." Science Daily. N.p., n.d. Web. 16 Oct. 2013. <www.sciencedaily.com>.
"THE BRAIN FROM TOP TO BOTTOM."Brain from top to bottom. N.p., n.d. Web. 17 Oct. 2013.
<http://thebrain.mcgill.ca/flash/i/i_03/i_03_cr/i_03_cr_par/i_03_cr_par.html>
"What is the nucleus accumbens? - Functions of the Brain - Sharecare."Expert Health
Information - Questions and Answers - Sharecare. N.p., n.d. Web. 16 Oct. 2013. <http://
www.sharecare.com/health/functions-of-the-brain/what-is-the-nucleus-accumbens>.
" This Strange Experiment from the 1950s. Motherboard | Home | Motherboard. N.p., n.d. Web.
16 Oct. 2013. <http://motherboard.vice.com/read/wireheading-1950s-wetware-hacking>.
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