Transcript Module 5 PowerPoint

The Biology of
Mind
PowerPoint®
Presentation
by Jim Foley
© 2013 Worth Publishers
Module 5: Tools of Discovery
and Older Brain Structures
Looking Deep into the Brain
What We’ll See:
How we learn about the brain:
Scans and more
The primitive, life-sustaining, inner parts of the
brain:
 The brainstem and limbic system
The Brain
What we’ll discuss:
how we learn about the brain
the life-sustaining inner parts of the
brain: the brainstem and limbic system
the outer, wrinkled “bark”: the cortex
left, right, and split brains
Questions about parts of the brain:
Do you think that the brain is the
sum of its parts, or is the brain
actually about the way they are
connected?
What do you think might happen if
a particular area of the brain was
stimulated?
What do you think might happen if
a particular area of the brain was
damaged or not working well?
Is it possible to
‘understand’ the brain?
“If the human brain were
so simple that we could
understand it, we would
be so simple that we
couldn’t.”
–Emerson M. Pugh
…but we can try.
for finding out
Investigating the BrainStrategies
what is different about the
mind when part of the
and Mind:
How did we move beyond
phrenology?
How did we get inside the
skull and under the
“bumps”?
by finding what happens
when part of the brain is
damaged or otherwise
unable to work properly
by looking at the structure
and activity of the brain:
CAT, MRI, fMRI, and PET
scans
brain isn’t working
normally:
case studies of accidents
(e.g. Phineas Gage)
case studies of split-brain
patients (corpus callosum
cut to stop seizures)
lesioning brain parts in
animals to find out what
happens
chemically numbing,
magnetically deactivating,
or electrically stimulating
parts of the brain
Studying cases of brain damage
When a stroke or injury damages part of the brain, we
have a chance to see the impact on the mind.
Intentional brain damage:
Lesions (surgical
destruction of brain
tissue)
 performed on animals
 has yielded some insights,
especially about less
complex brain structures
 no longer necessary, as
we now can chemically or
magnetically deactivate
brain areas to get similar
information
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Split-Brain Patients
 “Split” = surgery in
which the connection
between the brain
hemispheres is cut in
order to end severe
full-brain seizures
 Study of split-brain
patients has yielded
insights discussed at
the end of the chapter
We can stimulate parts of the brain
to see what happens
 Parts of the brain, and even neurons, can
be stimulated electrically, chemically, or
magnetically.
 This can result in behaviors such as
giggling, head turning, or simulated vivid
recall.
 Researchers can see which neurons or
neural networks fire in conjunction with
certain mental experiences, and even
specific concepts.
Monitoring activity in the brain
Tools to read electrical, metabolic, and magnetic
activity in the brain:
EEG:
electroencephalogram
PET: positron emission
tomography
MRI: magnetic
resonance imaging
fMRI: functional MRI
EEG:
electroencephalogram
An EEG (electroencephalogram)
is a recording of the electrical
waves sweeping across the
brain’s surface.
An EEG is useful in studying
seizures and sleep.
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PET: positron emission
tomography
The PET scan allows us to see what
part of the brain is active by
tracing where a radioactive form
of glucose goes while the brain
performs a given task.
MRI: magnetic
resonance imaging
MRI (magnetic resonance imaging)
makes images from signals produced by
brain tissue after magnets align the spin
of atoms.
The arrows below show ventricular
enlargement in a schizophrenic patient
(right).
fMRI: functional MRI
Functional MRI reveals
brain activity and
function rather than
structures.
Functional MRI
compares successive
MRI images taken a
split second apart, and
shows changes in the
level of oxygen in
bloodflow in the brain.
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Areas of the brain and their functions
The brainstem
and cerebellum:
The limbic
(border) system:
The cortex (the
outer covering):
• coordinates
the body
• manages
emotions, and
connects
thought to
body
• integrates
information
The Brain:
Less Complex Brain Structures
Our tour of the brain begins with parts of the human
brain found also in simpler animals; these parts
generally deal with less complex functions:
Brainstem (Pons and Medulla)
Thalamus
Reticular Formation
Cerebellum
Limbic System
The Brainstem:
Pons and Medulla
The Base of the
Brainstem:
The Medulla
 The medulla controls the most basic functions
such as heartbeat and breathing.
 Someone with total brain damage above the
medulla could still breathe independently, but
someone with damage in this area could not.
The Brainstem:
The Pons
The pons helps
coordinate automatic
and unconscious
movements.
The Thalamus (“Inner Chamber”)
 The thalamus is the “sensory
switchboard” or “router.”
 All sensory messages, except
smell, are routed through the
thalamus on the way to the
cortex (higher, outer brain).
 The thalamus also sends
messages from the cortex to
the medulla and cerebellum.
Reticular (“Netlike”) Formation
 The reticular formation is a nerve
network in the brainstem.
 It enables alertness, (arousal) from
coma to wide awake (as demonstrated
in the cat experiments).
 It also filters incoming sensory
information.
Cerebellum (“little brain”)
The cerebellum
helps coordinate
voluntary
movement such as
playing a sport.
The cerebellum has many other
functions, including enabling
nonverbal learning and memory.
The Limbic (“Border”) System
The limbic system coordinates:
 emotions such as fear and
aggression.
 basic drives such as hunger
and sex.
 the formation of episodic
memories.
The hippocampus
(“seahorse”)
 processes conscious,
episodic memories.
 works with the amygdala
to form emotionally
charged memories.
The Amygdala (“almond”)
 consists of two lima beansized neural clusters.
 helps process emotions,
especially fear and
aggression.
The Amygdala
 Electrical
stimulation of a
cat’s amygdala
provokes aggressive
reactions.
 If you move the
electrode very
slightly and cage
the cat with a
mouse, the cat will
cower in terror.
The Hypothalamus:
 lies below (“hypo”) the
thalamus.
 regulates body temperature and
ensures adequate food and
water intake (homeostasis), and
is involved in sex drive.
 directs the endocrine system via
messages to the pituitary gland.
Thalamus
The Hypothalamus as a Reward Center Riddle: Why did the rat
cross the grid?
Why did the rat want to
get to the other side?
Pushing the pedal that
stimulated the electrode
placed in the
hypothalamus was much
more rewarding than food
pellets.
Review of Brain Structures