BIOL 100 Chapter Notes - Chapter 4: Peripheral Nervous System, Limbic System, Reward System
Textbook Notes
Chapter 44
Drug Addiction
Concept 1: The Brain and the Limbic System
The Brain and the Limbic System
Brain can cope with complex tasks because of the way it is organized
It shapes your thoughts, emotions, concept of reality and behavior by following a rule known as
localization of function
Limbic system - controls the brain reward system
Connects the parts of your brain that are responsible for your ability to feel pleasure
Pleasure - reward given to you by doing an action necessary for your survival
Neuronal communication - utilizes neurons or nerve cells that have networks for passing messages back and
forth through the brain, the spinal column, and the peripheral nervous system
Communicate with each other via an electrochemical process
Synapses - neurons are special cells that connect with other cells by space connections which is
mediated by chemicals known as neurotransmitters
Neurotransmitters - chemical messengers are sent from one neuron to another through the synapse
Dopamine - key player in the reward system of the brain
Mesolimbic Dopamingeric System
Core of your brain reward system originates here
Thought to play a vital role in the development of addiction
Reward system is controlled by the release of dopamine
Dopamine - neurotransmitter found in regions of the brain that regulate movement, emotion, cognition,
motivation, and feelings of pleasure
The exact role of dopamine in reinforcement remains an active research area, and it is thought that the function
of dopamine is to enable reward-related stimuli to promote the learning of adaptive behavior that enables
survival
Dopamine triggers a cascade of reactions that allows a system to be motivated to perform a task and
repeat it if the reward is good
Addiction - necessity to repeat a behavior that leads to euphoric effect
Concept 2: What is a Drug?
What Is a Drug?
Drug - substance that when absorbed into the body of a living organism, alters normal bodily function
Have been used for centuries for medical indications
People can abuse and become addicted to both pharmacological drugs and recreation drugs
Food and Drug Administration - government agency responsible for regulating the 'legal' drug market
Drug Classifications
Drug - often classified according to the chemical structure
Depressants - slow down the CNS and produce a feeling of relaxation
Narcotics - slow down the CNS and block pain
Stimulants - speed up the CNS, increasing alertness and producing a sense of euphoria
Hallucinogens - slow down and speed up the CNS randomly, and alters perception
Concept 3: Disruption of Regulation Systems
Disruption of Regulation Systems
Drugs of abuse induce a larger level of dopamine than natural systems, and as a result, the regulation mechanism
used by the body to control this process is not followed
Illicit drugs of abuse can lead to downregulation of the reward system which means that the neurons begin to
reduce the number of dopamine receptors because they sense an unnatural flood of neurotransmitters
All drugs of abuse alter dopamine in some way
Reuptake - when the stimulus is removed, the neurons that released the dopamine reabsorb it and repackage it
into vesicles for later use
More dopamine accumulates in the synapse because it cannot be removed
Effect of dopamine lasts longer because it cannot be removed
After frequent use, the brain recognizes that there is too much dopamine floating around and that
dopamine overexposure is disruptive to the system
Down-regulation - leads to addiction because with a decrease in the number of receptors for dopamine, there will
be a decrease in how happy you feel when dopamine is released
You would then use more of that substance because there is not enough dopamine being released
People use drugs because drugs activate the rewarding system in the limbic system
Document Summary
Concept 1: the brain and the limbic system. Brain can cope with complex tasks because of the way it is organized. It shapes your thoughts, emotions, concept of reality and behavior by following a rule known as localization of function. Limbic system - controls the brain reward system. Connects the parts of your brain that are responsible for your ability to feel pleasure. Pleasure - reward given to you by doing an action necessary for your survival. Neuronal communication - utilizes neurons or nerve cells that have networks for passing messages back and forth through the brain, the spinal column, and the peripheral nervous system. Communicate with each other via an electrochemical process. Synapses - neurons are special cells that connect with other cells by space connections which is mediated by chemicals known as neurotransmitters. Neurotransmitters - chemical messengers are sent from one neuron to another through the synapse. Dopamine - key player in the reward system of the brain.
