CHAPTER 2: NEUROSCIENCE
Neurons and Neurotransmitters
ORIGINS OF STUDYING THE BRAIN
Plato believed that the mind
was located in the spherical
head
 Aristotle believed that the mind
was located in the heart
 Phrenology – Studying bumps
on the head to reveal a person’s
mental abilities and character
traits,

Franz Gall invented phrenology
 Gall was correct to conclude parts
of the brain have specific
functions. VIDEO: Racing and
the brain.

BIOLOGY AND BEHAVIOR
Biology is the foundation for our behavior and
mental processes
 Biological Psychologists – study links between
biology and behavior
 Neuroscience – interdisciplinary field studying
how biological processes relate to behavioral and
mental processes.

NEURAL COMMUNICATION
 Neuron
– nerve cell, the building block
of the nervous system
Each neuron consists of a cell body
(sometimes called the soma) and branching
fibers
 Neurons send out electrochemical
communications to the brain and the rest of
the body

 Dendrite
– receives information coming
from the neuron
NEURAL COMMUNICATION
 Axon
– Passes information to other
neurons, muscles and glands

Axons can be very long (unlike the dendrite
which is very short)
 Myelin


Sheath – insulates the axon
Helps impulses travel quickly
Importance of the myelin sheath is seen in
Multiple Sclerosis.

Consider MS – the myelin sheath breaks down and results
in slow communication to the muscles.
NEURAL COMMUNICATION
 Axon
Terminal Buttons ( aka end
buttons / branches, synaptic vessicles) –
the branched end of the axon that
contains the neurotransmitters. Reaches
right up to another neuron, muscle, organ.
PARTS OF A NEURON
ACTION POTENTIAL
 Neural

impulses are called action potential
Action Potential is a brief electrical charge that
travels down an axon
 Where
does an electrical charge come from?
During the resting potential axon gates are
closed and do not allow positively charged ions in.
negatively charged ions are on the inside.
 Electrical activity must get past the threshold to
fire.

ALL OR NOTHING


Neuron fires (aka Action Potential) --- + charged
ion comes into axon. Negative ions rush out.(this
depolarizes the axon) --- depolarizing causes the
next gate to open and then the next… etc. (like
dominoes)
Neuron’s Action Potential
 An “all or nothing response”


Like a gun firing or camera taking a picture… it does not go
halfway
Refractory Period
When the positive ions are pumped outside of the
axon. During the phase the neuron can’t re-fire as in
needs to recharge. FIELD TRIP TIME. YEAH!
FIELD TRIP

When you come back from our very brief field trip
answer how the flushing of a toilet is analogous
to the firing of a neuron. During which part of the
demonstration did the following occur?
“all or nothing” principle
 Resting potential
 Threshold
 Action Potential (neural impulse)
 Refractory Period

ACTION POTENTIAL
NEURON COMMUNICATION




Individual neurons function
as independent agents
within the nervous system
Synapse – junction between
the axon tip of the sending
neuron and the dendrite of
the receiving neuron
(junction is called the
synaptic gap)
From the axon terminal
buttons, neurotransmitters
travel across the synapse
ACTIVITY: Neural Network
NEURAL COMMUNICATION

LIVE!Psych (The Synapse and
Neurotransmitters)
NEURON COMMUNICATION (CONT.)



When the action potential reaches the end of
the axon, it triggers the release of
neurotransmitters (chemical messengers)
Neurotransmitters cross the synaptic gap and
binds to the receptor sites on the receiving
neuron
Excess neurotransmitters are reabsorbed by
the sending neuron – this is called reuptake

Many drugs today block the reuptake of
neurotransmitters. Ex Zoloft, prozac, Paxil for
Serotonin.
AN EXAMPLE OF REUPTAKE …
NEUROTRANSMITTERS
Neurotransmitters –
chemicals produced by
neurons that travel across
the synaptic gap and are
then used for
communication between
neurons for the performance
of mental and physical
activities.
 Q ANY EXAMPLES?

ACETYLCHOLINE (ACH)


Enables cognitive skill - learning and memory
Undersupply marks Alzheimer’s disease
DOPAMINE



Motor Movement
Oversupply is linked to schizophrenia.
Undersupply is linked to tremors and
decreased mobility (ex. Parkinson’s disease)
m Cell
Stem cell
Reading
PARKINSON’S DISEASE AND DOPAMINE
Michael J Fox Parkinson's Disease
 Michael J. Fox has Parkinson's
 Michael j fox on family guy

SEROTONIN


Mood Control
Undersupply is linked to
clinical depression
Selective Serotonin Reuptake
Inhibitors (SSRI) are a
frequently used drug for
depression (ex. Prozac, Paxil,
Lexapro, Zoloft) These drugs
increase the activity of
Serotonin.
 Anti-depressants and Placebo
effect. VIDEO- Penn and
Teller, Korea, college
students and alcohol, talking
to one person you can fully
trust.

NOR EPINEPHRINE


Influences
alertness and
arousal
Undersupply
can depress
mood
ENDORPHINS



Released in response to pain and vigorous exercise –
linked to pain and pleasure. Ex.- Donovan McNabb,
Jack Youngblood.
“morphine within”. Runner’s high, exercisaholics
Involved in addictions – Ex. Heroine
DRUGS AND HOW THEY AFFECT
COMMUNICATION AT THE SYNAPSE

Agonist v. Antagonist Drugs
 Agonist – mimic neurotransmitters (Excite)
Blocks reuptake of neurotransmitters
 Fits into the receptor site and function as
neurotransmitters


Antagonist – blocks neurotransmitters
(Inhibit)
Inhibit neurotransmitters from releasing
 Block receptor sites
 LIVE!Psych

AGONIST V. ANTAGONIST EXAMPLE

Ex. Dopamine
 Undersupply (Parkinson’s) – Agonist Drug.
Overdosage and hallucinations (grandfather)
 Oversupply (Schizophrenia) – Antagonist.


dyskenesia
Drugs such as heroine and morphine can take the
place of natural neurotransmission
 Brain stops producing natural opiates
 Body is in pain until the natural production of
endorphins begins again.