The Brain
Using lesions helps to understand the working of the
brain. What are lesions?
Older Brain Structures
• Earliest
ancestors
had a less complex
brains system
The Brainstem
• Oldest,
• Begins
innermost
where the
spinal cords swells
slightly after entering
the skull, medulla
 Function
 Controls heartbeat
and breathing
• Above
the medulla,
pons
 Function
 Helps coordinate
movements
• Brainstem
is the
crossover point
The Thalamus
•
Above the brainstem
 Function:
 Receives info from the
senses, except smell
 Sends info to higher
brain regions that
deal with the senses
 Receives the higher
brain replies, sends
info to the medulla
and cerebellum
The Tools of Discovery – Having
our Heads Examined
•
EEG
 Reads electoral activity in
your brain
•
PET
 Shows brains use of glucose
 Like a weather radar, shows
the “hot spots”
 Injects radioactive sugar
•
MRI
 Aligns atoms, then
disorients them
 Functional MRI
 Reveals brains functioning's
as well as its structure
The Reticular (net-like)
Formation
•
Inside the brainstem,
between ears
•
Neurons which run from
the spinal cord up through
the thalamus
 Function
 Filters incoming stimuli
 Relays important info to
together brain areas
 Controls arousal
 What happens if you
stimulate it?
 Cut it?
The Cerebellum (little brain)
•
Rear of brainstem
 Function
 Enables nonverbal
learning and memory
 Judges time
 Modulates our emotions
 Discriminates sounds and
texture
 Coordinates voluntary
movement
 Alcohols affect
 Not as coordinated
•
Injured
 Hard to wake, keep balance,
shake hands
 Movements jerky or
exaggerated
•
Occurs without conscious
effort, brain processes most
info outside of our awareness
The Limbic System
•
Between the new and old part
of the brain
•
Made up of the
 Amygdala
 Hypothalamus
 Hippocampus
•
Function
 Processes conscious memories
•
Injury
 Can’t form new memories
•
Tied to emotions fear and
anger and motives for food
and sex
The Amygdala
• Tied
to
aggression and
fear
• Discuss
the
rhesus monkey
and cat
The Hypo (just below) thalamus
•
Bodily maintenance
 Hunger
 Body temperature
 Sexual behavior
 Maintain a steady
internal state
(homeostatic)
 Monitors the state of your
body, tunes into your
blood chemistry and any
incoming orders from
together brain parts.
Discuss the examples
Unfortunately, it is possible for the hypothalamus to lose its ability to
communicate with leptin. When this happens, the hypothalamus continuously
instructs the cells of the body to increase fat storage by lowering the
metabolism, by being hungry and by burning sugar for energy - the exact
opposite of what should be happening for the body to function its best and
maintain a normal weight.
What that means is that for the girl on the left, her hypothalamus is correctly
sensing leptin and maintaining her body with normal weight, while for the girl on
the right, her hypothalamus is not correctly sensing leptin and therefore, her
body cannot lose weight, but continues to store fat, virtually regardless of how
little she eats or how much she exercises.
The Hypothalamus Cont.d’
• Rewards
centers
Addictive disorders may be due to
reward deficiency syndrome
The Cerebral Cortex
• Like
bark on a tree
• Function
 Perceiving, thinking
speaking
 Control and
informational
processing center
Structure of the Cortex
• Unfolded
what?
• 20
size of
– 23 billion what?
• 300
trillion what?
• Hemispheres’
cortex
is subdivided into
four lobes separated
by fissures (folds)
Functions of the Cortex
Motor Functions
• Right
controls
left and vice
versa.
Mapping the Motor Cortex
• Brain
has no sensory
receptors
• Body
areas requiring
precise control like ?
and ? occupy the
greatest amount of
cortical space
 Discuss experiments
with paralyzed
patients
Sensory Functions
•
Receives information from the
skin senses and movement of
body parts
•
More sensitive the body
region, the large the sensory
cortex area. Discuss lips and
whiskers.
•
Also have visual cortex in the
occipital lobes
•
Helps identify words, detect
emotions, recognize faces
•
Sound processed in auditory
cortex in temporal lobe.
Association Areas
•
Interprets, integrates, acts
on sensory information and
likes it with stored
memories.
•
Hard to map
•
In all four lobes
•
Frontal lobe
 Judgment, planning,
processing new memories
 Damage
 Alter personality, no
inhibitions, moral
judgment unrestrained
 Discuss Phineas Gage
•
Parietal lobes
 Enable mathematical and
spatial reasoning
•
Temporal lobe
 Recognize faces
The Brain’s Plasticity
•
Ability to modify itself after
damage.
•
May produce new brain cells,
neurogenesis
•
Sever brain and spinal cord
neurons usually do not
regenerated
•
Master stem cells found in the
human embryo
•
Some brain areas are
reassigned to specific areas
•
Some neural tissue can
reorganize in response to
damage
•
Plasticity may occur, especially
with kids
 Discuss figure 4.17, blindness and
deafness
•
Left hemisphere slow-growing,
right may pick up the language
 Discuss possibilities
Our Divided Brain
• What
is
lateralization?
• Thought
the right
side of the brain was
minor.
• Left
side damage
impairs reading,
writing, speaking,
arithmetic reasons,
understanding
Splitting the Brain
• Severed
the corpus
callosum which
carries messages
between them
• Discuss
the
experiment by
Gazzaniga, and
bothersome left-hand
independence
Right-Left Differences in the
Intact Brain
• Right
hemisphere
 Perceptual task
 Self awareness
 Discuss people
with stroke
• Speaks
or calculates
in the left hemisphere
• Discuss
sedative into
the neck artery
Fetal Alcohol Syndrome
• Brain of baby with no exposure
to alcohol
• Brain of baby with heavy prenatal
exposure to alcohol