Degeneration and recovery

Question 1

Tumor deveopment

Answer 1

• Benign and malignant

- Nerve cells cant divide (proliferate) so don’t become tumorous

Question 2

Benign tumors

Answer 2

-Does not infiltrate surrounding tissue but causes compression which can destroy brain tissue or cause hydrocephalus which can be life threatening

Question 3

Malignant tumors

Answer 3

• No defined boarders, can metastasise into the blood stream
• Can cause compression
• Contain cancer stem cells, even if tumour cells are removed, they initiate the growth of new ones (new treatments target these)

Question 4

Types of brain tumors

Answer 4

• Medulloblastoma - compresses fourth ventricle (hydrocephalus)
• Glioblastoma - glial cells
• Astrocytes - regulates chemicals in extracellular fluid
• Ependymoma - Ependymal cells (line ventricles and produce CSF)
• Oligodendrocytes - Glial cells (myelin sheath)
• Meningioma - meninges
• Pituitary adenoma - pituitary gland
• Neurinoma - schwann cells
• Metastatic carcinoma - secondary tumour
• Angioma - blood vessels
• Pinealoma - pineal gland

Question 5

Seizures

Answer 5

• Sudden distribution of the brain’s electrical activity (motor neurons) causes convulsion
• Hippocrates was first to suggest seizures are caused by brain damage

Question 6

Types of seizures

Answer 6

• Partial seizure: Affect localized regions

- Generalized seizure: Affects the whole brain

Question 7

Causes of seizures

Answer 7

• Scarring from brain injury e.g. stroke or tumour etc.
• High fever
• Alcohol and barbituate withdrawal can cause seizures as they are GABA agonists
• Alcohol and barbiturate withdrawal can cause seizures as they are GABA agonists
• Genetic factors can impact ion channels which can lead to over excitation
• Idiopathic

Question 8

Damage from seizires

Answer 8

-Damage hippocampus which creates memory problems

Question 9

Ischaemic strokes

Answer 9

• Cause: Arteries can be blocked by debris such as a blood clot or infection.
• Impacts: Blood flow is obstructed causing damage as oxygen is blocked
• Treatment: Antibiotics rid infection and anticoagulants remove blood clot.

Question 10

Hemorrhagic stroke

Answer 10

• Cause: blood vessels rupture due to high blood pressure or weak blood vessels which causes blood to leak into the brain.
• Impacts: pressure and subsequent damage due to lack of oxygen
• Treatment: high blood pressure meds or faulty vessels sealed

Question 11

Stroke damage

Answer 11

• Interruption to blood supply causes oxygen and glucose deprivation
• Attraction of microglia causes phagocytosis so white blood cells rush to the cite causing obstruction of capillaries.
• Sodium potassium transporters stop functioning leading to depolarization and the release of glutamate. Inflow of sodium increases, causing calcium to be absorbed to a toxic level which causes the cell to absorb water and swell and calcium-dependent enzymes are activated which destroy essential molecules e.g. mitochondria which produces free radicals which causes permanent damage (excitotoxic lesions)

Question 12

Stroke recovery

Answer 12

-Physiotherapy can slowly improve use of limbs impacted by stroke and also shows adjacent cortical areas take on functionality although some damage is permanent

Question 13

Traumatic brain injury

Answer 13

• Even Mild TBI can lead to neuro-degenerative disorders such as Alzheimer’s and Parkinson’s Diseases.
• Traumatized brain tissue leads to an increased production of glutamate and adenosine which promotes inflammation and causes damage

Question 14

Fetal alcohol syndrome

Answer 14

• Drinking alcohol during pregnancy is linked to increased risk of miscarriage
• Pregnant women should not drink more than 1-2 UK pints 1-2 times a week
• Exposure to alcohol affects neural plasticity and brain development causing physical and neuropsychological issues e.g. deficits in IQ, attention, coordination, and social interaction

Question 15

Parkinsons symptoms

Answer 15

-Resting tremor in hands and face, rigidity during volitional movements

Question 16

Parkinson’s impact on Basal ganglia pathways

Answer 16

-Substantia nigra produces dopamine causing striatum to release GABA
-Parkins stops the production of dopamine so the indirect pathway is excited and the direct is inhibited
Gpi becomes hyperactive causing inhibition in the motor cortex

Question 17

Treatment

Answer 17

• L-dopa
• deep brain stimulation
• Fetal tissue transplant

Question 18

L-dopa

Answer 18

• Decreases tremors and increases speed of movements

- Stops working If there are too few dopamine terminals/neurons left and may cause hallucinations instead)

Question 19

Deep brain stimulation

Answer 19

-Implanted into subthalamic nucleus (Gpi) so patient can electrically stimulate their own brain. This removes some additional excitatory input to Gpi and reduces excessive inhibition to improve motor abilities

Question 20

Foetal tissue transplant

Answer 20

• Ethically controversial as tissue is obtained from the substantia nigra of aborted fetuses and implanted into the striatum
• Dopaminergic foetal cells are able to grow and secrete dopamine which initially reduces symptoms and can cause painful involuntary movements
• Mutated protein thought to cause dopamine neuron death may transfer to grafted neurons

Question 21

Multiple sclerosis

Answer 21

-Autoimmune disease in which the immune system attacks the myelin sheaths and creates sclerotic plaques. Interrupts normal transmission of neural messages throughout the spinal cord and brain.

Question 22

Cause of multiple sclerosis

Answer 22

-Childhood virus may weaken the blood-brain barrier or virus may attach itself to myelin or may be contracted during pregnancy which increases child’s susceptibility

Question 23

Remitting-relapsing MS treatment

Answer 23

• Interferon is a protein which modulates responsiveness of immune system which has been shown to reduce frequency and severity of attacks
• Glatiramer acetate is a random combination of amino acids found in myelin which may act as a decoy for the immune system

Question 24

HIV

Answer 24

• Targets and infects astrocytes which leads to apoptosis
• This impacts frontal regions, basal ganglia, hippocampus & white matter
• This can cause dementia, loss of language and movement difficulties

Question 25

HIV therapy

Answer 25

-Combination antiretroviral therapy, if started early after infection, can prevent or minimize brain damage. Cognitive and affective abilities should be monitored as active viruses may persist in the brain even if not detectable in the blood

Question 26

Herpes simplex

Answer 26

• Herpes simplex (usually HSV-1) can proliferate and travel down the nerve fibers to the mucous membrane of the mouth, if it travels to the brain herpes encephalitis is caused which attacks the frontal and temporal lobe
• HSV-1 (oral herpes) can become HSV-2 (genital herpes)

Question 27

Herpes treatment

Answer 27

-High doses of intravenous acyclovir (Zovirax) leads to 80% survival but long term memory and cognitive impairment may be seen

Question 28

Parkinsons and alzheimers

Answer 28

• Neurodegenerative processes cause loss of neurones and subsequent loss of function. Basal ganglia degenerates causing dopamine receptors to die which prevents voluntary movement.
• Understanding neurodegenerative processes allow us to develop neuroprotective agents and new treatments

Question 29

Phineas Gage

Answer 29

o Went from being kind to aggressive due to damage to pre-frontal lobe

• Lost moral insight, behaviour intensified by immediate reward
• Emotion based information about the world in order to help guide our future behaviour and helps consider the long-term consequences of our actions by weighing up rewarding and punishing outcomes of our behaviour
• If part of our pre-frontal cortex is damaged, then we lose this ability and our behaviour becomes driven by immediate reward.
• Understanding the neural circuity involved In emotion-driven behaviour is crucial
• It allows us to better understand many neurological and psychological disorders that have emotional dysregulation as a symptom