Nucleus AccumbensPleasure Center of the Brain

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Location in the brain:

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Functions:

•Motivation and Reward•Addiction•Laughter•Pleasure•Fear•Placebo Effect

Works on: Dopamine and Serotonin

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Three Studies:

James Oldes and Peter Milner (1950s)

Schaepfer, Sackeim, Luber et al. (2007)

Nikolai Axmacher (2010)

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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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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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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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Sackeim, Luber et al. (2007)Aim: Treat severely depressed patients who have not responded to treatment, with deep brain stimulation.

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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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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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Axmacher (2010)Aim: The relation between the nucleus accumbens and the formation of surprising events

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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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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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Dysfunctions

•Depression•Drug Addiction•Tourette Syndrome•ADHD•Impulsive Choice•Lack of Motivation

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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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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-stimulation-therapies.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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