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Lecture 3

PSY100H1 Lecture Notes - Lecture 3: Resting Potential, Frontal Lobe, Motor Cortex

Course Code
Ashley Waggoner Denton

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Biological foundations
Deadline for online questionaire
PSYNUp- open for experiments
Tutorial – thursday January 31st -5-6 LM159 – Q and Answer session
Academic success centre – 3-4 14 college street
nature and nurture are intertwined
Research on twins- monozygotic twins – helpful for research because they are genetically
identical- what is nature vs nurture?
The nervous system
body's electrochemical communication circuitory
nerve cells – make up nervous system
1 cm ^3 cube would contain 50 million nerve cells; brain = 80 billion nerve cells
CNS – the brain + spinal cord
peripheral nervous system- deals with every other part of the body
somatic nervous system- external environment
autonomic nervous system – internal sensation
sympathetic system
parasympathic system
are the basic unit of the nervous system
operate through electrical impulses
are excitable- communicate with other neurons through chemical signals
3 types
Sensory neurons- info from environment to the brain- I am feeling this in my hand right now
Motor neuron- info from the brain to the external world- tell your hand to hold the water bottle
interneuron – reflect arc
SAME – sensory afferent motor efferent
Neuron parts
come in all different shapes and sizes
the picture is just the general part idea
Dendrites- branch like extension from neurons- receive info from the other nearby neurons
cell body- integrates all the info that dendrites receive
axon – along which axon potential flows or propogates
mylein sheath- help info move quickly down the axon
White matter- axon
Cell body = grey matter
terminal button- contains vesicles with neurotransmitters
neurons don't touch one another- they use electrochemical signal- released into the synapse and
collected by the other dendrites
How is a neuron like a 14 year old girl?
one presynaptic neuron, one post-synaptic
is the person excited enough to pass the information along to other person
is she being encouraged by other people or inhibiting? Whole bunch of peopple= whole bunch
of neurons?
A single neuron gets info from many other neurons – it has to decide what to do with the info

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Excitatory signals
increase the likelighood of passing on the neuron- depolarize the neuron- making it likely that
they will fire
Inhibitory signal- make it hyperpolarized- doesn't fire
The whole reason neurons works is because they are polarized
When do neurons fire?
Action potential- neuron impulse that passes along the axon – causing the release of chemicals
(neurotransmitters) from the terminal buttons to be picked up by other neurons
All- or – none – neurons either fire or don't. What can differ the frequency of firing – it can keep firing
or stop- but it doesn't kind of fire- you either pass the info or you don't
Blue = outside the neuron
Inside = neuron
polarization – when neuron is not firing – the inside is more negatively charged than outside at its
resting state
the two ions we focus on are potassium and sodium ions
these ions can only travel through their specific channels
if the gates are closed they can't travel through
Resting membrane potential – stick figure diagrams
K+ = females
Na+= males
boy specfic and girl specific doors
bouncers are blocking the doors
at the resting membrane potential- the guys only let girls through – so more potassium ions
inside- na+ outside
as soon as sodium channels open- the guys rush in; girls freak out and rush out second later
Things balance back out – repolarization – more negative inside than outside
stored in vesicles
during an action potential- at the end of an axon- the neurotransmitters fuse at the membrane
and get let otut
synapse = space between pre and post synaptic neuron
particular neurotransmitter locks on to a specific post synaptic neuron
**What's a synaptic cleft?
3 things can happen
If there is a lot of neurotransmitters in synapse – to stop signalling, it can lock onto autoreceptor
to signal stop sending neurotransmitters
Reuptake- neurotransmitter is released back into the neuron
Enzyme deactivation- breaks down neurotransmitters so can't attach to the receptor
A lot of common neurotranmitters
1. acetylcholine- responsible for motor control at muscles and joints- bottocks- small dose of
bottulism- prevents acetly choline from working – it paralyzes movement- no wrinkles
2. epinephrine- adrenaline -old school term- responsible for rapid energy
3. norepinephrine- similar – responsible for alertness
4. serotonin- low levels of serotonin = depression disorder;*** SSRI what increases serotonin and
decreases obsessive compulsive disorder?

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5. Dopamine- rewarding behaviour
6. GABA- major inhibitory neurotransmitter; glutamate- major excitory neurotranmitter
How drugs work? 2 types
1. Agonist- enhance neurotransmitters' actions
- it can do this in a number of ways:
- drug might increase the release of neurotransmitters (release more)
-block the re-uptake of neurotransmitter
- mimicking a neurotranmitter- lock onto post synaptic receptor – and by activating it-
e.g. cocaine, methamphetamine- increase the effect of dopamine – by limiting it's uptake
2. Antagonists- inhibit neurotransmitters actions by:
- block the release of neurotranmistters
- destroy the neurrotranmitters in the synapse
- mimick a neurotransmitter- but instead of activating the postsynaptic receptor, it locks onto it
and blocks it by preventing the actual neurotransmitter from binding
e.g. beta-blocker – prevent epinephrine from locking to the beta receptors
botox- inhibits the effect of acetyl choline
Brains clearing up myth
1. size of the brain has no correlation to their intelligence- elephants and whales have a larger
brain than humans- if you look at the ratio of body mass to brain mass – 1:15; others' is 1:180-
we have an advantage – particular parts of the brain like cortex tend to be larger
2. We only use 10% of our brains = myth came from William James – the average person rarely
achieves portion of his/her potential – fernology – you can figure out a lot about person's
personality depending on where the bumps on someone head were
plasticity – brains are extremly adaptive
The brain- from the bottom up
1. brain stem- survival
2. cerebellum- cauliflower looking important for movement
3. subcortical structures- emotions and basic drive
4. Cortical structure- complex mental activity as well as motor control
The brain stem
responsible for those things that keeps you alive – super basic survival needs – e.g. digestive
system control
reticular formation- network of neurons extends from brain stem and go all the way to
cerebellum -responsible for allertness structure
cor coordinated movement and balance
belly dancing for coordinated movement and balance -bell = cerebellum
What happens when alcohol reaches cerebellum? - you lose control
master regulatory structure
hypothalmus links neurochemical system to hormone system(endocrine system)
Vital to 4 things:
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