Psychology 2221A/B Study Guide - Final Guide: Benzodiazepine, Sympathetic Nervous System, Radial Arm Maze
23 Jun 2018
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Final Exam Review
Brain Damage and Neuroplasticity
Brain Tumors
- Tumor neoplasm- mass of cells that grows independently of the rest of the body- a cancer
- 20% of the brain tumors are meningioma’s (encases in meninges)
- encapsulated
- usually benign, surgically removable
- cause damage through pressure
- Most brain tumors are infiltrating
Grow diffusely into surrounding tissue
Malignant (potential to grow and spread elsewhere)
Difficult to remove or destroy
- About 10% of brain tumors are metastatic –originate elsewhere, usually the lungs
Cerebrovascular Disorders
Stroke A sudden onset cerebrovascular event that causes brain damage
- 2 types:
Cerebral Hemorrhage (bleeding in the brain)
Aneurysm: a weakened point in a blood vessel that makes a strokes more
likely; may be congenital (present a birth) or due to poison or infection
Cerebral Ischemia (disruption of blood supply)
Thrombosis: a plug forms in the brain
Embolism: a plug forms elsewhere and moves to the brain
Arteriosclerosis: wall of blood vessels thicken, usually due to fat deposits
(most common)
Damage Due to Cerebral Ischemia: does not develop immediately- i-2 days to
develop fully, most damage is a consequence of excessive NT release. Blood-
deprived neurons become overactive and release all of glutamate. Glutamate
over activates its receptors, leading to influx of Na+ and Ca+-- This triggers:
more glutamate, internal reactions that ultimately kill the neuron
- Leading cause of death and adult disability
- Symptoms include aphasia, amnesia, paralysis, cognitive impairments and coma
- Infarct: where the actual stroke occurs- tissue is dead and remains dead
- Penumbra: area surrounding infarct- potential to reverse effects of stroke
- Diagnosis? Cerebral angiogram
Closed Head Injuries
- Blow to head: does not penetrate the skull- the brain collides with the skull, causing
injury
Contrecoup injuries get hit on one side and injury will be found on other side
- Contusions: damage to the cerebral circulatory system: hematoma forms (bruise on brain)
- Concussions: disturbance of consciousness following blow to the head but no evidence of
structural damage
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- Chronic Traumatic Encephalopathy: (CTE) progressive degenerative disease occurs after
repetitive mild traumatic brain injury Symptoms include memory loss, social instability,
erratic behaviour, slowness of muscular movement
Infections to the Brain
Encephalitis: inflammation of the brain due to invasion of microorganisms
- Bacterial Infections
Often leads to abscesses, pockets of puss
May inflame meninges, creating meningitis
Syphilis- general paresis
Treat with penicillin and other antibiotics
- Viral Infections
Some preferentially attack neural tissues
Rabies, measles, mumps, influenza
Some can lie dormant for years
- Neurotoxins
May enter general circulation from the GI tract or lungs, or through the skin
Toxic Psychosischronic insanity produced by a neurotoxin
The Mad Hatter hat makers often has a toxic psychosis due to mercury exposure
Some antipsychotic drugs produce a motor disorder called tardive dyskinesia
Some neurotoxins or endogenous (produced by the body) e.g. autoimmune
disorders
Epilepsy
- Primary symptom= seizures
- Not all who have seizures have epilepsy
- Epileptics have seizures generated by their own brain dysfunction
- 1% of population
- Difficult to diagnose due to diversity and complexity of epileptic seizures
- No cure, frequency and severity reduced by meds, surgery in extreme cases
- Causes?
Brain damage- caused by viruses, neurotoxins, tumors, closed head injuries
Genes- over 70 known so far
Faults at inhibitory synapses
- Diagnosis
EEG- electroencephalogram
Seizures associated with high amp spikes (spikes can last up to 12 hours)
- Seizures often preceded by aura (e.g. smell hallucination or feeling)
- Aura’s nature suggests the epileptic focus
- Warns epileptic of an impending seizure
- 2 major categories of epilepsy:
1. Partial Seizures (part of brain)
Simple
Symptoms are mainly sensory or motor or both
Symptoms spread as epileptic discharge spreads
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Complex
Often restricted to temporal lobes
Patient engages in compulsive and repetitive behaviours (automatisms)
2. Generalized Seizures (whole brain)
Grand Mal
Loss of consciousness and equilibrium
Tonic-clonic convulsions: rigid (tonus) & tremors (clonus) and
Cyanosis
Resulting hypoxia may cause brain damage
Petit Mal
Not associated with convulsions
A disruption of consciousness associated with a cessation of ongoing
behaviour
Kindling Model of Epilepsy
- Mild electrical stimulation administered via implanted electrodes; Convulsive response
becomes progressively stronger with repeated administration
- Produced by stimulation distributed over time (min. 2 hours)
- Neural changes are permanent. If kindled, can leave untouched for months- next
stimulation= convulsions
- Problem? Very rarely occur spontaneously (like human epilepsy)
- Kindling phenomenon= development of epilepsy seen following a head injury
Parkinson’s Disease
- Movement disorder of middle and old age affecting about 1-2% of population
- Tremor at rest most common symptom of full blown PD
- Muscular rigidity, difficulty initiating movement, slowness of movement
- Dementia is not typical
- No single cause
Neurotoxins, brain injury, concussions, genetics, herbicides, pesticides
Lower incidence in coffee drinkers and smokers
- Associated with degeneration of the substantia nigra
Release DA to striatum of the basal ganglia
- MPTP Model of Parkinson’s Disease
The case of the frozen addicts
Synthetic heroin produced the symptoms of Parkinson’s
Contained MPTP
MPTP causes cell loss in the substantia nigra, similar to PD
Animal studies led to the finding that deprenyl can retard the progression of PD
- Mexico has more causes of Parkinson’s disease, because used to use MPTP on crops
Huntington’s Disease
- Degenerative motor/cognitive disorder
- Incidence: 1/10 000 (rare); males>females
- Symptoms:
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Document Summary
Tumor neoplasm- mass of cells that grows independently of the rest of the body- a cancer. 20% of the brain tumors are meningioma"s (encases in meninges) encapsulated usually benign, surgically removable cause damage through pressure. Malignant (potential to grow and spread elsewhere) About 10% of brain tumors are metastatic originate elsewhere, usually the lungs. Stroke a sudden onset cerebrovascular event that causes brain damage. Aneurysm: a weakened point in a blood vessel that makes a strokes more likely; may be congenital (present a birth) or due to poison or infection. Thrombosis: a plug forms in the brain. Embolism: a plug forms elsewhere and moves to the brain. Arteriosclerosis: wall of blood vessels thicken, usually due to fat deposits (most common) Damage due to cerebral ischemia: does not develop immediately- i-2 days to develop fully, most damage is a consequence of excessive nt release. Blood- deprived neurons become overactive and release all of glutamate.
