Download Drug and Alcohol Abuse

DO NOW
• Make another name tag
• What is a brain cell called?
• Name the four major lobes of the brain
• Name three parts of a brain cell
• What do all drugs of abuse have in common?
Drug and Alcohol Abuse
Week 2: Introduction to the Brain
Goals of today
• (1) You will become familiar with the major
parts of the brain and be able to describe their
function.
• (2) You will be able to explain how brain cells
send and receive information.
Why do we care about the brain?
• All drugs of abuse change dopamine levels in
the brain. (this will be on your test).
• If we understand how dopamine levels in the
brain arise in the first place, we can better
understand drug abuse
• More on this later..
The Brain
The most heterogeneous part of our body
In other words—it is the most complex.
What makes up the brain?
• Brain cell, or neurons.
– ~100 billion
• Glial (glue) cells
– ~300 billion
Neurons come in different shapes and
sizes
The brain is part of the central nervous
system (CNS)
• The central nervous system (PNS) consists of
– The brain (400 billion cells)
– Spinal cord
• The peripheral nervous system (PNS)
– Most physical sensations are via PNS
– All other nerve cells
• Think taste cells on your tongue, cells in your gut that tell you that
you are full, cells that regulate your heart beat
– More cells in the PNS than CNS
– Will not talk much about the PNS, although, drugs of abuse
can affect these cells
• i.e. withdrawal symptoms, nausea, etc.
CNS
• The Brain
– 3 major divisions
• (1) Cerebellum
• (2) Brain Stem
• (3) Forebrain
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–
–
–
(a) Cerebral cortex
(b) Limbic System
(c) Basal Ganglia
(d) Diencephelon
Cerebellum
• Integration of movement and stability
• Very sensitive to alcohol
– Think field sobriety test
• Fun fact: 90% of your brain cells are in the cerebellum
• Funner fact: you can live without a cerebellum and be
pretty OK for the most part.
Brain Stem
• Medulla
• Pons
• Midbrain
• Together important for heart rate, breathing,
and reflexes
Brain Stem
• Regions of the brain stem are organized in
nuclei
– Clusters of similar neurons
– Dopamine, serotonin, and norepinephrine nuclei
Brain Nuclei You Need To Know
• Substantia Nigra/ Ventral Tegmental Area
– Dopamine (DA)
• ***rewarding properties of food, drugs, sex, etc
• *** all theories of addiction imply this brain region
• Raphe nuclei
– Serotonin (5-HT)
• Locus Coeruleus
– Norepinephrene (NE)
Diencephelon
• Thalamus
– Relay center from the sensory
• All sensory and motor input here
– Olfaction doesn’t get processed here
• Hypothalamus
– Hunger, satiety, motivation for food
– Contains pituitary gland (growth, hormones)
Basal Ganglia
• Globus Pallidus
• SN/VTA Targets
– Striatum
• (motor)
• Caudate
• Putamen
– Nucleus accumbens
• (motivation/reward)
• Shell
• Core
Limbic system
• Amygdala
– Emotion/mood
– Fear
• Hippocampus
– Memory and learning
Cerebral Cortex
• Two hemispheres
• Four lobes
– Different functions for each lobe
Four Lobes
Border of Frontal and Parietal Lobe
Motor cortex
Somatosensory cortex
Summary I
• That was a lot of information!
• How can you remember all of that?
–
–
–
–
Make a list of all the structures we covered today
Then, write down what each structure does.
Repeat about 3 times
Then, you will be good for the test.
• What is the MOST important take home?
– All drugs of abuse elevate dopamine in the nucleus accumbens.
(We will give you proof!).
– Without dopamine elevation in the nucleus accumbens,
addiction to drugs of abuse cannot occur.
What makes up the brain?
• Brain cell, or neurons.
– ~100 billion
• Glial (glue) cells
– ~300 billion
Neurons come in different shapes and
sizes
3 parts
(1) Cell body: where all major
cell functions happen (has the
nucleus and organelles)
(2) Dendrites: part of the
neuron that “receives”
information. Can listen to
many cells at once.
(3) Axon: part of the neuron
that “sends” information
• Usually wrapped in
myelin (sends signal
faster)
• Branches out into
several “axon
terminals”
• Can talk to many cells
at once
Neurons
For simplicity
• We will not talk about electrical properties of
neurons too much
– What is important is that a cell is “excited” or
“inhibited”.
– Excited: causes the neighbor neuron to release
neurotransmitter to another neuron
• When excited, neurons produce “action potentials”
• Action potential: electricity, that begins in the dendrite,
travels down the cell body, and down the axon.
– Inhibited: prevent the neighbor neuron from releasing
neurotransmitter to another neuron
• When inhibited, no action potentials are fired.
Communication between cells: axon
terminals form “synapses” with
dendrites of other cells
PRESYNAPTIC NEURON
POSTSYNAPTIC NEURON
Signal sending and Signal receiving
occurs at the synapse
• Neurons “talk” by
– Releasing neurotransmitters into the synapse
PRESYNAPTIC NEURON
POSTSYNAPTIC NEURON
Signal sending and Signal receiving
occurs at the synapse
• Neurons “listen” by
– Sensing neurotransmitters into the synapse via
proteins called “receptors”.
PRESYNAPTIC NEURON
POSTSYNAPTIC
NEURON
Synapse
• It is a space between the axon terminal and
dendrite.
– Axon terminal releases neurotransmitter into the
synapse (space)
– Dendrite picks up the neurotransmitter.
Neuron Activity
Another example
A
B
We say the flow of information is
going from cell A to D
C
D
Another example
A
B
C
In this case, cell B is a GABA neuron, and release
GABA. This shuts down cell C, which can no longer
fire an action potential.
D
Recap
• (1) Neurons release neurotransmitters from their axon terminals.
• (2) The neurotransmitter can excite or inhibit the neighbor neuron
– Excite: causes the neighbor neuron to release neurotransmitter to
another neuron
– Inhibit: prevent the neighbor neuron from releasing neurotransmitter
to another neuron
• (3) All communication in the brain works this way.
• (4) when billions of these cells work together, communicate
together, you get
–
–
–
–
Thought
Feelings
Pleasure
Pain, etc
Preview of next week
The synapse
Types of neurotransmitters
• Excitatory
– Glutamate
– Acetylcholine
• Inhibitory
– GABA
– Acetylcholine
• Modulatory (can excite, inhibit, and other things, dependng on the
context)
– Dopamine, serotonin, norepinephrine
How do neurotransmitters
excite/inhibit?
• Key (ligand, neurotransmitter) and Lock
(receptor)
https://www.youtube.com/watch?v=p5zFgT4a
ofA
More on this later
• Next week:
• Neurotransmitters and how they act in the
brain.
• Due next week: Addiction Science in the
News.
Discussion