The Basic Brain
Chapter 2, Lecture 4
“Our brain processes most information
outside of our awareness.”
- David Myers
The Brain:
Older Brain Structures
The Brainstem is the oldest part of the brain, beginning
where the spinal cord swells and enters the skull. It is
responsible for automatic survival functions.
Brainstem
The Medulla [muhDUL-uh] is the base of
the brainstem that
controls heartbeat and
breathing.
Brainstem
The Thalamus [THALuh-muss] is the brain’s
sensory switchboard,
located on top of the
brainstem. It directs
messages to the sensory
areas in the cortex and
transmits replies to the
cerebellum and
medulla.
Brainstem
Reticular Formation is
a nerve network in the
brainstem that plays an
important role in
controlling arousal.
Cerebellum
The “little brain”
attached to the rear of
the brainstem. It helps
coordinate voluntary
movements and
balance.
Listen to some interesting
research on tickling…
Cerebellum
Research also indicates that part of the
cerebellum’s function is to tell the brain what
to expect from the body’s own movements. In
this way, the brain can ignore expected
pressure on the soles of the feet while walking
and attend to more important sensations such
as stubbing a toe.
Cerebellum
Sarah-Jayne Blakemore and her colleagues at
University College, London, have addressed the
interesting question, “Why can’t we tickle ourselves?”
For their study, the researchers had six volunteers lie
in a brain-scanning machine with their eyes closed. A
plastic rod with a piece of soft foam attached to it
moved up and down, tickling the participants’ left
palms. The experimenter and the volunteers took
turns moving the rod, so the volunteers were either
tickling themselves or were being tickled. In a third
condition, the foam was secretly removed, so the
volunteers moved the rod by felt nothing.
Cerebellum
Throughout this process, the researchers used
functional MRI (fMRI) scans to compare activity in
different parts of the brain. On the basis of the
results, they concluded that during self-tickling one
part of the brain tells another: “It’s just you. Don’t get
excited.” The cerebellum is involved in predicting
the specific sensory consequences of movement. It
provides the signal that is used to cancel the sensory
response to self-generated stimulation. In short, it
tells the somatosensory cortex what sensation to
expect and this dampens the tickling sensation.
Blakemore, S., Wolpert, D., & Frith, D. (1998). Central cancellation of
self-produced tickle sensations. Nature Neuroscience, 1, 635-640.
The Brain
Techniques to Study the Brain
A brain lesion
experimentally
destroys brain tissue to
study animal behaviors
after such destruction.
Hubel (1990)
Clinical Observation
Clinical observations have shed light on a
number of brain disorders. Alterations in brain
morphology due to neurological and
psychiatric diseases are now being catalogued.
Tom Landers/ Boston Globe
Electroencephalogram (EEG)
An amplified recording of the electrical waves
sweeping across the brain’s surface, measured
by electrodes placed on the scalp.
AJ Photo/ Photo Researchers, Inc.
PET Scan
Courtesy of National Brookhaven National Laboratories
PET (positron emission
tomography) Scan is a
visual display of brain
activity that detects a
radioactive form of
glucose while the brain
performs a given task.
MRI Scan
MRI (magnetic resonance
imaging) uses magnetic
fields and radio waves to
produce computergenerated images that
distinguish among
different types of brain
tissue. Top images show
ventricular enlargement in
a schizophrenic patient.
Bottom image shows brain
regions when a
participants lies.
Both photos from Daniel Weinberger, M.D.,
CBDB, NIMH
James Salzano/ Salzano
Photo
Lucy Reading/ Lucy
Illustrations
The Limbic System
The Limbic System is a
doughnut-shaped
system of neural
structures at the border
of the brainstem and
cerebrum, associated
with emotions such as
fear, aggression and
drives for food and sex.
It includes the
hippocampus, amygdala,
and hypothalamus.
Amygdala
The Amygdala [ahMIG-dah-la] consists
of two lima beansized neural clusters
linked to the emotions
of fear and anger.
Hypothalamus
The Hypothalamus lies
below (hypo) the
thalamus. It directs
several maintenance
activities like eating,
drinking, body
temperature, and
control of emotions. It
helps govern the
endocrine system via
the pituitary gland.
Reward Center
Sanjiv Talwar, SUNY Downstate
Rats cross an electrified
grid for self-stimulation
when electrodes are
placed in the reward
(hypothalamus) center
(top picture). When the
limbic system is
manipulated, a rat will
navigate fields or climb
up a tree (bottom
picture).
Page 67
Homework
Read p.68-75
“To be learning about the neurosciences now is
like studying world geography while Magellan
was exploring the seas. This truly is the golden
age of brain science.”
- David Myers