Transcript Biology and Behaviour

Biology and Behaviour
Psychology 1106
Introduction



Seems to me that if we are to truly
understand behaviour and that if we
accept that the brain controls it, we
must understand the brain
The nervous system is built out of
neurons or nerve cells, and glial
cells, which are sort of the glue
Glial cells do other support functions
too
Neurons

Three basic parts
• Cell body
• Axon

Sends out info
• Dendrite


Receives info
Myelin sheath
• Insulates neurons, speeds transmission
Neurons

The neuron fires when stimulated
• Heat
• Light
• Pain
• Other neurons
• Pressure

The impulse is called an action
potential
Electrical activity of the neuron

Resting potential
• About -70 mV
• Selectively allowing certain ions in
• With stimulation Na+ is allowed in

Action potential
• Changes in one area lead to changes in
another
• Chemical to electrical, very cool
The action potential



Resistance and myelin affect
transmission rate
Less resistance with a big axon
Normally you have a resting
potential because a process called
Active Transport pump out Na+ and
pulls K+ in (3:2) so you get a
negative charge across the cell
membrane
The Sodium Potassium Pump





Active transport takes
energy
Easier encoding?
Faster reaction?
An Action potential
happens when
stimulation causes the
pump to sort of stop,
Na gets in, K goes out
Sort of reversed later
My neurons are firing right now

After a neuron fires it must recharge
so to speak
• Refractory period



A neuron is either on or off
At the end of the axon there is a gap
between it and the next dendrite
This gap is called the synapse
• A Greek word meaning ‘gap’
Every mall in Athens has a store
called The Synapse….






Neurotransmitters are released
across the synapse by the axon
Bind to a receptor site at the
dendrite
Lock and key sort of
Key opens an ion channel
Causes an action potential in the
next neuron….
Great place for drug interactions
The Neurotransmitters


Acetylcholine (Ach)
Monoamines
• Catecholamines



Norepinephrine (NE)
Epinephrine (E)
Dopamine (DA)
• Indoleamine

Seretonin (5-Ht)
• Others

Histamine (H)
More neurotransmitters

Amino Acids
• Glutamate (universally excitatory)
• GABA (universally inhibitory)
• Glycine
• Proline

Peptides
• Substance P
Finally….

Morphine like substances
• Endorphins
• Enkephalins

Other peptides
• Insulin
• Prolactin
• HGH
• Vasopressin
More on synapses

Agonists
• Mimic neurotransmitters or make brain make
more
• Morphine is an endorphin agonist

Antagonists
• Bind to receptor sites or neurotransmitter
molecules

Sometimes the brain can’t get a drug
because of the blood-brain barrier
• Glial cells around blood vessels
The Nervous system

Central Nervous system (CNS)
• Brain, spinal column, cerebellum
• Communication is neural

Peripheral Nervous system (PNS)
• Nerves that make you move basically
• Communication is neural
How does it work?





Bicep curl for example
Muscle needs an agonist and an
antagonist
Motor neuron sends message to
bicep to curl up
Sensory neuron tells you when to
stop
Simple behaviour LOTS of neurons
In a Moth’s Ear….


Moth Ear basically
has two neurons
A1 and A2
They are not
frequency
sensitive, but do
not respond to low
frequencies
Those would be some tiny Q
tips…..
Do Moths Have Ear Wax?




A1 is responsive to
intensity
More firing with
closer bat
A2 only fires with
very loud sounds
A2 fires, bat must
be very close
Moths and Bats, Charts and
Graphs





A1 on the left fires,
that wing beats faster
Moth’s course corrects
to 180 degrees from
bat
So very and totally
cool
A2, go crazy
2 neuron ear can
encode where a
predator in in 3
dimensional space!!!
Autonomic Nervous System







Different communication than in the CNS
and PNS
Not neural, more chemical
Hormones secreted into bloodstream by
‘ductless glands’
Pituitary gland is the master gland
Example, pituitary controls release of
pitocin and oxytocin which start labour
Another example, effects of testosterone
on spatial ability
psychoneuroendocrinology
THE BRAIN
BRAIN BRAIN BRAIN
One more brain diagram
EEG

Oldest form of
brain imaging
CAT Scan

Computerized axial
tomography
PET scan

Positron emission
tomography
MRI

Magnetic
Resonance
Imaging
Function and Form

Brainstem
• Medulla
• Reticular formation

Thalamus
• Sort of a ‘sensory switchboard’

Cerebellum
•
•
•
•
‘little brain’
Walking
Balance
Skilled movement
Form and Function

Limbic system
• Hippocampus

Memory
• Amygdila

Emotion (?)
• Hypothalamus

Homeostasis
• Nucleus accumbens

reward
Cerebral Cortex


Covers the hemispheres
Wrinkled
• More area


Lots of connections to other regions
Different lobes
• Frontal -> complex cognition
• Parietal -> space, vision
• Temporal -> sensory stuff, language
• Occipital -> vision
Hemispheres








Left and right
Left Language
Right spatial
Split brain patients do not
have a corpus collossum
Recognize pictures faster
in left visual field
Recognize words faster in
right
Very cool
This left brained right
brained stuff is nonsense
Genetics, Evolution and Behaviour



We have no problem accepting that
“animals’” behaviour is somehow
affected by genetics
What about us?
OF COURSE IT IS, WHAT MAKES YOU
THINK YOU ARE SO SPECIAL?
Introduction
‘Trying to determine how much of a
behaviour is due to genetics and how
much is due to the environment is
like trying to determine how much
the area of a field is caused by its
length and how much by its width’
Donald Hebb
 Nature v. Nurture is a stupid
argument

A little background




You get half of your genes from your
mother and half from your father
Single genes can affect a
characteristic
Many genes can affect a
characteristic
It is always an interaction
An Example

Human Ocular cutaneous albinism
•





I wonder where that example came from…..
Single gene for the production of
melanin
A – normal
a - bad
Dominance / Recessive relationship
AA, aA, Aa all lead to normal, aa
leads to me


Leslie and Rick
Aa and Aa
•
•
•
•

Or some variation
aA and Aa
Aa and aA
aA and aA
Phenotypically
normal



1 in 4 chance of
having a kid with
aa
They did, on June
23, 1965
My genotype MUST
be aa because
there is no
dominance
They got the looks, but I got the brains……..


Danny and
Stephanie may be
carriers, or they
may not be, they
are phenotypically
normal
Their kids could
carry the allele,
assuming they do


My kids MUST
carry the allele, as
they had an a from
me, and, an A from
Isabelle
We know they got
an A from Isabelle
by looking at their
phenotype
Behavioural Effects






I don’t spend much time in the sun
I have very poor vision (20/200,
melanin guides the growth of the
visual system)
No binocular vision
Can’t drive a car
Not very good at baseball
Huge IQ…….
Evolutionary Psychology





Homo sapiens sapiens showed up
somewhere between 100 000 and
200 000 years ago
Civilization happened 10 000 years
ago.
For most of our existence we were
hunter/gatherers
Men hunted
Women gathered, did child care
Evolution rocks


Evolutionary psychology takes our
history into account and makes some
amazing predictions
Predictions that no other type of
psych makes, and it helps organize a
very diverse data set
Predictions of evolutionary
psychology







More abuse towards
adopted kids
Men want youth
Women want
resources
Incest taboo
Racism
Sugar is sweet
We are better at
detecting cheating in a
social context



Men are more
promiscuous than
women
Women having affairs
have more orgasms
with their lover
Men sleeping around
have more killer
sperm in their
ejaculate
Misinterpretations

Just because someone says they are
an evolutionary psychologist does
not mean that
• They believe in the status quo
• They believe things cannot change
• They believe things are morally right

Evolutionary psychologists believe
that natural selection has affected
our behaviour
Further Reading



‘The Selfish Gene’ and ‘The Blind
Watchmaker’ by Richard Dawkins
‘Sex, Evolution and Behavior’ by Daly
and Wilson
‘Evolutionary Psychology’ by
Cosmides and Tooby