Lesson 3

1. Lesson 3 How Nicotine Interacts with the Brain

2. A look at the brain Different parts of the brain are involved in different functions, like vision, movement, thinking, memory.

3. Eating makes me happy! 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 good! VTA NA

4. 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

5. 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

6. 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. Dopamine is released at axon terminals in the NA and prefrontal cortex. VTA NA 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.

7. What is the impact of nicotine interacting with the reward pathway? Addiction!

8. 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

9. 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