Brain Damage:
I. Brain tumors: a mass of cells that grow independently of the rest of the body
1. meningiomas: tumors that grow between meninges
2. infiltrating tumors:
3. 10% are metastatic
II. Cerebrovascular disorders (stroke or
apoplexy): 2 types
1. cerebral hemorrhage: bleeding into the brain
when a cerebral blood vessel ruptures
A. aneurysm: a balloon-like swelling in the wall of a blood
vessel.
2. cerebral ischemia: blood supply is
disrupted to a part of the brain
A. thrombosis: blockage of the blood flow by a plug at the
site of its formation
B. embolism: a plug formed in a larger blood vessel &
carried to a smaller one
C. arteriosclerosis: blood vessel walls become narrow due
to a build up of fat deposits (plaque)
3. excitatory amino acids (glutamate) cause stroke related brain
damage
A. cells in the immediate vicinity die & this can not be
helped
B. blood deprived neurons become overactive & release
excessive amounts of glutamate
a. this overstimulates
neighboring postsynaptic cells (penumbra) causing excessive ion exchange
b. the excessive ion influx ultimately kills
neighboring neurons
c. possible preventive treatments:
III. closed head injuries: caused by blows that do
not penetrate the skull
1. contusions: are internal hemorrhaging or a hematoma (brain bruise)
A. they occur when the brain slams against the inside of the
skull
2. concussion: involve a temporary
disturbance of consciousness (sometimes
not literally passing out) with no noticeable
bleeding or structural damage
3. punch-drunk syndrome (dementia pugilistica): caused by repeated
concussions
IV. Infections of the brain: these cause encephalitis or inflammation of the
brain.
1. bacterial infections: lead to cerebral
abscesses (puss pockets in the brain)
A. they often attack & inflame the meninges
(meningitis)
B. Examples:
a. syphilis is a bacterial brain infection &
may lead to insanity & dementia
b. gonorrhea:
bacteria that can infect the meninges
2. viral infections (2 types)
A. rabies in an example of a viral injection that
damages the brain
B. AIDS Related Neurological Disorders:
C. herpes: a virus that can infect the meninges
3. possible slow acting viruses:
A. Kuru: It occurred in cannibals
in
B. Alzheimer’s Disease: Diagnosis is not positive until
tissue analysis is done.
a. cortical atrophy
& ventricular enlargement
b. dendritic shrinkage
c. senile plaques: deformed axon terminals
d. neurofibrillary
tangles: pathological webs of neurofilaments
V. Neurotoxins: can enter thru the mouth, lungs, & skin
(particularly harmful in younger organisms)
1. mercury: was used in the preparation of felt
to make hats (mad as a hatter)
2. lead: British poor steeped their tea in
cracked ceramic pots with lead cores & this caused
psychosis (term “crackpot” came from this)
3. antipsychotic meds: are toxic & can
result in tardive dyskinesia
A. symptoms: smacking & sucking of the lips, tongue
rolling, lateral jaw movement, puffing
of cheeks
4. ETOH: chronic use can lead to dementia (Korsakoff’s
disease)
A. maternal use can cause birth defects
Recovery from Brain Damage
1. age of the subject appears to be important
A. prenatal damage or damage soon after birth is often more
devastating than in adulthood.
B. younger organisms are more vulnerable to toxins (e.g., ETOH)
& malnutrition
C. younger organism’s have a greater potential for axon sprouting
D. neurons that would have died normally may survive after injury
in young organisms
II. when recovered abilities may deteriorate
1. in times of stress recovered abilities may
seem to deteriorate i.e., deficits return
2. as we get older recovered abilities may
deteriorate
III. possible recovery processes
1. learned adjustments in behavior
A. example: move head more to compensate for a loss in
peripheral vision
B. example: teaching someone to use an injured limb when
they do not believe they can
2. damaged axons & dendrites may grow
back under some conditions
A. axon regrowth may follow the myelin
in the PNS
a. they may not grow to the correct destination
B. CNS damage causes scar tissue (from astrocytes)
formation which is a barrier for regrowth
C. trophic factors may be needed
a. nerve growth factor: released (when their is axon damage) by the postsynaptic cell
b. gangliosides: combined carbohydrate & fat molecules
3. denervation supersensitivity: increased number of receptors after
axonal loss
4. previously less effective synapses may be strengthened
A. when reading Braille with one finger the amount of
sensory cortex devoted to that finger increases
a. these changes in cortical maps often occur
within minutes
IV. use of some drugs (diazepan)
apparently can inhibit behavioral recovery
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Brain & Human Nature Outlines