How the Brain Works The Facts Visually Explained by DK (z-lib.org)

COMMUNICATION

Reward Centers

Reward Centers

The brain’s reward system evolved because it helped

us seek out things that are important for our survival.

But if this system is hijacked, it can lead to addiction.

Reward pathways

When we do something that is important for our survival,

such as eating when hungry, or having sex, neurons that

trigger the release of the neurotransmitter dopamine are

activated in the ventral tegmental area (VTA). These send

signals to an area called the nucleus accumbens—a rush in

dopamine here tells the brain this is a behavior that should

be repeated. Neurons also send signals to the frontal cortex,

which focuses attention on the beneficial activity.

Route to reward

The reward system starts in the VTA in the

midbrain, then passes to the nucleus

accumbens in the basal ganglia and then the

frontal cortex. Dopamine also travels from

the substantia nigra to the basal ganglia.

This pathway affects motor control.

Stimulus

The initial stimulus can originate

outside the body, such as the sight of

food, or from within, such as falling

glucose levels.

Urge

Dopamine released from the

VTA to the nucleus accumbens drives us

to seek out and work for the reward

that is linked to the stimulus.

Reward

The reward triggers parts of the

brain known as “hedonic hot spots” to

release opioid-like neurotransmitters,

giving a sense of pleasure.

Action

A region of the frontal cortex

weighs the inputs and decides whether

to seek the reward. The body then

acts to reach it.

NUCLEUS

ACCUMBENS

V TA

SUBSTANTIA

NIGRA

LIMBIC SYSTEM

LIGHT ENTERS EYE

1

2

5

4

Desire

The urge may be registered as

a conscious desire in the cortex, but

sometimes it goes undetected, or even

opposes our conscious desires.

Learning

If the reward is better than

expected, the brain releases more

dopamine, strengthening the connection

between stimulus and reward.

3

6

Attention

focused on

activity

Dopamine neurons

activated and project

to other brain areas

Rush of dopamine tells

brain to repeat activity

Sensory

information

registers in

limbic system

RF

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US_112-113_Reward_Centers.indd 112 20/09/2019 12:36