Week 11/2 Degen Disord Et Al. Flashcards Preview

Intro Behavioral Neuroscience (PSYC 211) > Week 11/2 Degen Disord Et Al. > Flashcards

Flashcards in Week 11/2 Degen Disord Et Al. Deck (31):
0

A tumor is ?
▪ A benign tumor has ?
▪ If the tumors infiltrates the surrounding tissue, it is ? (i.e. cancerous).

A tumor is a uncontrollable growth of cells that serves no useful function.
▪ A benign tumor has a distinct border between the tumor cells and the surrounding tissue (i.e. it is encapsulated).

▪ If the tumors infiltrates the surrounding tissue, it is malignant (i.e. cancerous).
Malignant tumors give rise to a process of metastasis in which tumor cells travel through vascular system and grow elsewhere in the body.

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Any tumor in the brain, benign or malignant, is harmful.
▪ Tumors are damaging to the brain because:


- the tumor occupies space and compresses the brain
tissue.

- the tumor invades the surrounding tissue as it grows
and destroys cells in its path.

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tumor of the cells of the meninges is called a?

meningioma
It has displaced the right side of the brain.
The right ventricle is almost completely occluded.
Non malignant, benign in x.

Low other types names in text?

3

Glioma are the most ?

common and serious type of tumor. Grow from glial cells
Different specific types:
- Astrocytoma (astrocytes)
- Ependymoma (ependymal cells that line the ventricle)
- Medulloblastoma (cells in the roof of the fourth ventricle)
- Oligodendrocytoma (oligodendrocytes)

Extract and then try to destroy with radiation.

4

Seizure Disorders (Epilepsy)
▪ A seizure is period of sudden, excessive activity of cerebral neurons.


▪ If the cells constitute the motor system, the seizure will cause a wild, uncontrollable activity of the muscles called a convulsion.

Types of seizures?
▪ Partial seizures have a definite focus and remain localised.

▪ Diagnosis relies on EEG; epilepsy is associated with bursts of high amplitude EEG spikes which occur during an attack.

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Types of partial seizures?

▪ Partial seizures have a definite focus and remain localised.
- Simple partial seizures involve changes to consciousness.
- Complex partial seizure lead to loss of consciousness.

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What of seizure happens during rem sleep

Act out dreams or interact with ordinary ppl.
Can report experience.

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Generalised Type Seizures: Grand Mal
Explain.
note has focus,

Generalised seizures are widespread involving most of the brain.
▪ A grand mal seizure is the most severe of all seizures. Preceding the seizure, the patient will experience:
changes in mood sudden jerks of muscular activity before waking
an aura; a peculiar sensation or psychological change
(e.g. a bad smell, hallucination, bright lights; euphoria).

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What are the Grand Mal Seizure phases?

-Clonic Convulsion
▪ The grand mal seizure begins with the tonic phase:
- muscles contract forcefully
- arms outstretch rigidly
- patient makes an involuntary cry (patient is
unconscious)
- patient holds a rigid posture for 15 seconds

▪ In the clonic phase:
- muscles tremble
- muscles jerk convulsively (quickly at first)
- eyes roll
- face is contorted (tongue may be bitten)
- sweating and salivation
- after 30 seconds, muscles relax; breathing begins
again
- patient falls into an exhausted sleep

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Generalised Seizures: Petit Mal
Aka?
EEG pattern?

▪ Children have spells of petit mal (absence) seizures:
- - - -
- -
vacant look
blink eyes repeatedly
unresponsive

can occur up to 100 times a day; they can be disruptive to normal day to day activities and often go undiagnosed

seizures frequently cease at adolescence

The EEG of a petit mal seizure shows a bilateral symmetrical pattern of a 3-per second electrical discharge.

10

Seizures have many causes including?

▪ The most common causes of seizures:
- scarring produced by stroke, injury or irritating effect of a
growing tumor.
- alcohol or barbiturate withdrawal (this can be fatal). Increase inhibit ation over firing

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Seizures have serious consequences

▪ Almost half of the patients who have seizures will show evidence of damage to the hippocampus

▪ A single episode of status epilepticus (during which the patient experiences a series of seizures without regaining consciousness) causes excessive glutamate release during the seizure.
▪ Thus, NMDA receptors are involved in seizures.

Too much calcium, enters cell

Causes supsensitity, essp. Alcohol abuse, increase nmda.
Known as up regulation. Over acticity of glutamate

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Seizures are related to NMDA receptor activity

▪ NMDA receptors control calcium channels.
▪ Alcohol blocks NMDA receptors.
▪ Long-term suppression of NMDA receptors (due to alcohol abuse) causes supersensitivity (up-regulation).
▪ When an alcoholic suddenly stops drinking, the suppressed NMDA receptors suddenly rebound.
▪ The increased activity of NMDA receptors cause seizures.

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Cerebrovascular Disorders aka?

▪ Strokes are sudden-onset cerebrovascular disorders that cause brain damage.

▪ A hemorrhagic stroke is caused by bleeding within the brain. It occurs when a cerebral blood vessel ruptures due to high blood pressure.

▪ Ischemic strokes are caused by a disruption of the blood supply to an area of the brain. These are three main types

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There are three main causes of ischemia:

- a blood clot (thrombus) that forms in the blood vessels (e.g air bubble, tumor, fat).
- an embolus, carried through the bloodstream, lodges itself preventing the flow of blood.
- an arteriosclerosis is caused by thickening of the arteria

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Stroke-induced release of glutamate kills neurons

▪ Sodium-potassium channels stop functioning due to lack of oxygen and glucose.
▪ The neuron membrane depolarises which causes excessive glutamate release.
▪ Excessive glutamate triggers excessive influx of Na+ and Ca2+ ions by way of NMDA receptors.
▪ Excessive Na+ and Ca2+ is toxic to the cell.
• excessive Na+ causes the cell to absorb water and swell.
• inflammation attracts white blood cells which obstruct capillary walls.
• Damaged mitochondria produce free radicals

See process photo

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Stroke Treatments for you to know?

▪ Administer an anticoagulant to prevent blood clotting (e.g. warfarin). Used mainly for thrombotic cases.

▪ Desmetoplase is an anticoagulant derived from a enzyme found in vampire bats. It can be injected directly into the brain. It can reduce stroke related clinical symptoms 9 hours after the stroke.

▪ Dissolve blood clot to re-establish blood circulation (e.g. tPA: tissue plasminogen activator). However, tPA can be toxic if it crosses the blood brain barrier.

▪ Reduce risk factors: high blood pressure, cigarette smoking, diabetes, high cholesterol.

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Developmental Disorders: Toxic Chemicals

▪ The presence of toxic chemicals during pregnancy (e.g rubella) can lead to abnormal fetal development and cause mental retardation.

▪ Chronic alcohol consumption during pregnancy can lead to fetal alcohol syndrome. Issue d facial deformation and abnormal brain dev. Drink during critical period. Uh oh!

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Developmental Disorders: Inherited Metabolic Disorders

▪ “Errors of metabolism” refer to genetic abnormalities in which the recipe for a particular enzyme is in error so the enzyme cannot be synthesized.

▪ Children with phenylketonuria (PKU) are unable to convert phenylanine into tyrosine (both are amino acids).
- Excessive phenylanine interferes with myelinization of
neurons after birth.
- Place child on low-phenylamine diet otherwise severe
mental retardation

▪ Tay-Sachs disease is caused by an accumulation of waste products in the brain.
- Lysosomes lack an enzyme that normally breaks down
waste products.
- The lysosomes get larger as waste accumulates causing
eventual swelling of the brain.
Symptoms! See book, incl. seizure?

19

Developmental Disorders: Downs Syndrome

▪ Downs syndrome is a congenital disorder (present at birth).
▪ It is caused NOT by a faulty gene, but because of an extra
21st chromosome.
▪ The syndrome is associated with the mothers age; a higher risk of downs syndrome with age.
▪ Down syndrome is easily recognisable:
What happens after 30? Brain degenerate, thin dulcimer, ad

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Down syndrome is easily recognisable by?

- round heads
- thick, protruding tongues. Keep mouth open.
- stubby hands, low set ears, slanting eyes, short stature.
- slow to learn
- brains are 10% lighter; sulci and gyri are smaller and
simpler.
- small frontal lobe and thin superior temporal gyrus

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▪ Transmissible spongiform encephalopathy (TSE) is a contagious brain disease which gives the brain a sponge- like appearance. They are fatal.

- BSE: Bovine spongiform encephalopathy (‘mad cow
disease’)
- Creutzfeldt-Jakob disease (transmitted to humans from
cows) chd
- Kuru (humans only), b/c eat brains
- Scrapie (sheep only)

▪ Symptoms include:
- dementia (loss of memory and personality; hallucinations)
- speech impairment
- ataxia; changes in gait, rigid posture
- seizures

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TSE is caused by a proteins called ?

prions (protein infectious agents).
▪ Healthy prions (PrPc) are found in membranes where they play a role is synaptic function.
▪ The infectious protein (PrPSc) is identical to the healthy protein.
▪ PrPc and PrPSc differ in their 3d shape; the difference is in the way the protein is folded.
▪ Once the misfolded PrPSc is introduced into the cell, it causes healthy PrPc to misfold aswell.
▪ PrPSc’s are resistant to proteolytic enzymes and heat.

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Mad cow, not reversed by overheating nor

Proteoleic enzymes. So resistant to prions poor quality,

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Degenerative Disorders: Parkinson’s Disease

Parkinson’s disease (PD) is caused by degeneration of the nigrostriatal system.

Surviving dopaminergic neurons show Lewy bodies: abnormal circular structures in the cytoplasm.

▪ PD is associated with a mutation of a gene located on chromosome 4.
The gene normally produces α- synuclein which is involved in synaptic transmission in dopaminergic neurons

Abnormal accumulation of α-synuclein is toxic to the cell and causes aggregations in dopaminergic neurons. Lewy bodies consist of these aggregations.

25

Treatments for Parkinson’s Disease

▪ L-DOPA replenishes the brain of its lost dopamine. This does not work indefinitely.

▪ In 1982; seven people in north California (mid twenties) were hospitalised for displaying dramatic clinical symptoms.
- total paralysis, no speech, constant drooling, eyes open
with fixed stare, shuffling with slow gait. ➔ Parkinsonian

▪ They had all taken a a synthesized heroin (demoral) which contained MPTP (1-methyl-4-phenyl-1,2,3,6- tetrohydropyridine).

▪ Primates treated with MPTP show cell loss in substantia nigra.

▪ Deprenyl blocks the effects of MPTP.

MPt model of Parkinson's disease

26

Surgical Treatments for Parkinson’s Disease

▪ Transplantation of fetal tissue (rare)
- tissue obtained from substantia nigra of aborted human
fetuses and implanted into the striatum.
- not a routine procedure as many patients complain of
painful, involuntary movements (dyskinesias)

▪ A potential source of dopamine cells could come from cultures of stem cells
- stem cells are undifferentiated cells that have the ability
to develop into a variety of cell types.

▪ Destruction of the the internal division of the globus pallidus (pallidotomy) or the subthalamic nuclei.

27

Alzheimer’s disease (AD) is characterised by progressive memory loss and other mental functions.
What are the neural correlates of Alzheimer’s Disease


▪ AD produces severe degeneration of the hippocampus, entorhinal cortex, subbiculum, association cortices of the frontal and temporal lobes, the nucleus basalis (ACh), raphe nuclei (5- HT) and the locus coeruleus (NA).

Two types of cellular abnormalities:
▪ Amyloid plaques consist of a dense protein core (β-amyloid) surrounded by degenerating axons and dendrites

▪ Neurofibrillary tangles comprise dying neurons that contain accumulations of twisted filaments of phosphorylated tau protein.

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Accumulation of β-amyloid in brains of Alzheimer patients

▪ The accumulation of amyloid plaques is caused by a defective form of β- amyloid.

▪There are two form of β- amyloid: a long and short form.

▪ In AD, the abnormally high concentration of the long β- amyloid causes them to misfold and aggregate which cause brain degeneration.

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Genetic causes of AD

▪ The mutation of the gene APP (amyloid precursor protein) leads to familial AD.
- This mutation is also responsible for tangle deposits.
- Mutation in the gene for tau deposits produce tangles only
and are typically associated with frontotemporal dementia.

▪ A mutation in the gene for apolipoprotein E (ApoE) increases the risk of late-onset AD by interfering with the removal of the long form of β-amyloid.

Brains of Downs Syndrome also contain β-amyloid deposits. Thus, the 21st chromosome may be involved in the production of this protein.

Seems less imp. This slide!

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Other neurological disorders to be aware of

▪ Amyotrophic lateral sclerosis attacks the spinal cord and cranial nerve motor neurons. Symptoms: spasticity, exaggerated stretch, muscle weakness and eventual paralysis.

▪ Multiple sclerosis is an autoimmune demyelination disease: myelin sheaths are attacked by the immune system. Normal neural transmission is interrupted.

▪ Korsakoff’s syndrome is caused by chronic alcoholism which leads to thiamine (vitamin B1) deficiency.

▪ Infectious disorders (encephalitus, rabies, meningitis)