Lesson 3
How Nicotine Interacts with the Brain
A look at the brain
Different parts of the brain are involved in different functions, like
vision, movement, thinking, memory.
The Reward Pathway
The reward pathway is a neural pathway used for
reinforcing behaviors that are important for survival.
Nicotine also stimulates the reward pathway.
This feels
Eating
makes
me
happy!
good!
VTA
NA
Dopamine is the neurotransmitter in the
reward pathway
Stimulation of neurons in the VTA area results in release of
dopamine in the NA (emotional center) and the prefrontal cortex
(thinking).
VTA
NA
How does nicotine affect neurotransmission?
•
•
•
•
•
Nicotine binds special receptors on the dendrites of certain neurons.
An electric impulse travels down the axon.
Dopamine is released at the axon terminals into the synapse.
Dopamine binds receptors on the next neuron.
This may lead to an electric impulse down second neuron.
nicotine
Synapse
How does nicotine interact with the
reward pathway?
This
feels
good!
Nicotine binds to receptors
on neurons in the VTA.
An electrical impulse
travels down the neuron
axon.
VTA
NA
Dopamine is released at
axon terminals in the NA
and prefrontal cortex.
Dopamine binds to dopamine
receptors on other neurons.
This leads to the rewarding
effects of smoking, such as
relaxation, a “buzz”, or an
increased ability to focus.
What is the impact of nicotine
interacting with the reward
pathway?
Addiction!
What genes might be involved in variation in
smoking behavior?
Nicotine
receptors
Dopamine receptors;
enzymes that make or
break down dopamine
Enzymes involved in
nicotine breakdown
What genes are included in the
smoking behavior study?
• Two regions in the dopamine receptor gene (DRD2), which codes
for a protein that binds dopamine, found on the dendrites of
receiving neurons
• One region in the dopa decarboxylase gene (DDC), which codes for
a protein involved in dopamine synthesis, found in the axons of
neurons that release dopamine
DDC
DRD2