The Nucleus Accumbens

By: Nicole, Tobias & Kristine

Where is it located?

The nucleus accumbens is located at the base of the forebrain, the largest part of the brain.

The word accumbent is defined as lying down or leaning against something in a position of comfort.

Description The nucleus accumbens is a brain

region involved in functions ranging from motivation and reward to feeding and drug addiction.

The Nucleus accumbens is typically divided into two major subdivisions, the shell and the core.

Sometimes called the brain’s “pleasure center”, this cluster of neurons modulates the effects of the neurotransmitter dopamine, on which many neural circuits depend.

The nucleus accumbens is a link in the brain pathways that cause addiction and depression.

Connection the Rest of the Brain

The major interaction is with the ventral tegmental area (VTA) which connects via the mesolimbic pathway

Dopaminergic input from the VTA activates the Nucleus Accumbens

Dopamine is a neurotransmitter and it activates the Nucleus Accumbens whenever we feel pleasure

Addiction Lab research points to a relationship

between addiction and the release of seratonin and dopamine in the nucleus accumbens.

The surge of these neurotransmitters triggers neural activity correlating with the addicts’ high and the sensation of reward on which addiction depends.

When someone craves a substance, neural activity increases in anticipation of future pleasure.

Placebo Effect Nucleus Accumbens is

responsible for the expectancy for reward

When a fake reward is administered, the dopamine is released

High Dopamine release causes a high and a “good feeling,” which helps heal the body

Research 1) Dean Sabatinelli, 2007

• Pleasure rather than salience activates human nucleus accumbens and medialprefrontal cortex

2) Mary Kay Lobo, 2010

• Why Cocaine Is So Addictive: Activation of Specific Neurons Linked to Alterations in Cocaine Reward

3) Traute Flatscher-Bader, 2010

• According to researchers from Australia, the connection between nicotine and alcohol addiction may lie in the nucleus accumbens.

Dean Sabatinelli Pleasure rather than salience activates human nucleus

accumbens and medial prefrontal cortex

Free viewing of pleasant images of erotic and romantic couples prompts clear, reliable increases in nucleus accumbens (NAc) and medial prefrontal cortex (mPFC) activity

However, equally arousing (salient) unpleasantimages, and neutral pictures, do not

Data suggest that in visual perception, the human NAc and mPFC are specifically reactive to pleasant, rewarding stimuli, and are not engaged during by unpleasant stimuli, despite high stimulus salience.

(Sabatinelli, 2007)

Mary Kay Lobo

Why Cocaine Is So Addictive: Activation of Specific Neurons Linked to Alterations in Cocaine Reward

Cocaine corrupts the brain and becomes addictive

Discovered connected activation of specific neurons to alterations in cocaine. The results may help researchers in developing new ways of treating those addicted to the drug.

Two main neurons (D1 and D2) in the nucleus accumbens region of the brain, exert opposite effects on cocaine reward.

• Activation of D1 neurons increases cocaine reward

• Activation of D2 neurons decreases cocaine reward

(Lobo, 2010)

Traute Flatscher-Bader According to researchers from Australia, the connection between

nicotine and alcohol addiction may lie in a pleasure center in the brain, called the nucleus accumbens, which also plays an important role in addiction.

Describes an overlap of the effect of alcohol and nicotine in the brain

Analyzed the expression of thousands of genes in the post-mortem brain tissue of smokers, alcoholics and those who enjoyed both drugs

Discovered that a specific group of genes expressed in the nucleus accumbens were most active in people who abused both alcohol and nicotine

When overactive, these genes alter the structure of cells in the nucleus accumbens and may rewire this brain region

• This finding may help us understand why both drugs are often consumed together ; each drug appears to enhance the addictive properties of the other

Flatscher-Bader, 2010

Dysfunction of the Nucleus Accumbens

Research shows that damage to the Nucleus Accumbens can cause:

Lack of motivation and inhibits addictive behavior.

Impulsive choice

ADHD (attention deficit hyperactivity disorder)

Tourette syndrome

Thanks for listening