Natural Reward Pathways Exist in the Brain
Neurons Transmit Messages in the Brain
-Neurons send chemical and electrical messages through the brain. They send messages to cause movements, feel pain, or even to store memories.
The Reward Pathway Reinforces Behavior
-Different areas of the brain are responsible for different things. The reward pathway, which is responsible for emotions, motivation, and reward, is in the center of the brain.
-The reward pathway gives us good feelings when we do something beneficial to our survival.
-The reward pathway connects to many important areas of the brain, which helps it make better connections to reward "good behavior."
-When engaging in this "good behavior", the five senses collect information and send it to the brain. The brain realizes that there are memories of "rewards" when this behavior occurs, like feeling full after eating. The reward pathway then uses certain neurons to release dopamine, which gives you a happy feeling. The pathway then uses is connections to memory to make sure you engage in this behavior often.
-When the reward pathway interacts with motor controls, it strengthens connections that will help this behavior happen. For instance, picking up the sandwich, chewing, and swallowing.
Neurons Communicate Via the Synapse
-Information crosses between neurons over the synapse. In this area, the signal is transferred from electrical to chemical to electrical again.
Other Cells in the Brain
-Glia cells play a role in complex brain functions.
-Types of glia: oligodendrocytes, microglia, astrocytes
-Oligodendrocytes make up the myelin sheath, which makes the action potential move up to 30 times faster than it would without the sheath.
-Microglia are unique immune cells that can detect infected or damaged neurons and destroy bacterias and viruses.
-Astrocytes hold neurons in place, bring them nutrients, and digest dead neurons. Though it remained unknown for a good amount of time, the astrocytes do interact with neurons and their messages. They can interact with thousands of synapses at once, but they don't overlap each other.
-Astrocytes release a substance called a "gliotransmitter", which sends messages much the same way that a neuron sends its messages.
Drugs Alter the Brain's Reward Pathway
The Physiology of the High
-Drugs can cause dramatic changes within seconds.
-Drugs pass the senses and go directly to the brain.
The Brain's Coping Mechanism
-The brain has to adapt to the drugs it takes in, and it often does so by reducing the number of receptors for the drugs. This means that next time the drug is taken, more has to be used to be effective. This is known as "tolerance."
Drug Delivery Methods
-The faster a drug reaches the brain, the more addicting it is.
-Smoking a drug is the fastest way to experience a high.
-The speed in which the effect reaches the brain can affect different areas of the brain.
-Slow delivery can help to recover from addiction.
Hardwiring an Addict
-Overusing a drug can cause other areas besides the reward pathway to become affected.
-Affected dendrites are thicker and longer.
-Once the brain is "hardwired", an addict becomes driven by habit and need for the drug they used.
Changes Last Long After Use
-Even an addict who hasn't used drugs for 100 days still has very low brain activity.
Death By Overdose
-Changes that drugs make are so dramatic that too much of a drug can kill you.
How Drugs Can Kill
-Many drug overdose deaths are caused by using many drugs at once.
-Heroin causes more deaths by overdose than other drugs.
-Most drugs cause fatal problems through different mechanisms. Restricted breathing, unconsciousness, and constricted muscles all are examples of fatal effects of drugs.
