Week 40- Global Brain Dysfunction and Cognition Flashcards
What is the roles of the medulla oblongata?
Control centre for most vital functions
What is the roles of the reticular-activating system (RAS)?
Network of nuclei and neurons throughout brain stem –> connected to many parts of the brain –> determines degree of arousal
What is the role of the cerebellum?
Coordination of movements
Posture and balance
What is the role of the thalamus?
Relay station for sensory impulses
What is the role of the hypothalamus?
Homeostasis
Autonomic nervous system and lots of the endocrine system
Body temp, fluid, food, sleep cycles, stress,
Where is the Basal ganglia located?
Deep in the hemispheres
What does the basal ganglia control?
Coordination and control of skeletal muscle
What is the limbic system involved in?
Aversion/reward
Emotions and memory
What structure is involved in Parkinson’s disease?
Basal ganglia
What area is involved in fear and anxiety?
Amygdala
What neurons are important for reward/pleasure?
Dopaminergic neurons
Where do dopaminergic neurons act for the reward centre?
N Accumbens
Where is the source of Dopaminergic neurons?
VTA (ventral tegmental area) –> in the midbrain
What increases increased release of dopaminergic neurons in the N.Acc?
5-HT
What releases 5-HT?
Raphe neurons in the midbrain
What is aphasia?
Inability to comprehend or express language
What is expressive aphasia?
Inability to speak or write –> damage to Broca’s area –> motor aphasia
What is Receptive aphasia?
Inability to understand written or spoken words –> damage to wernicke’s area –> sensory aphasia
What is Dysarthria?
Inability to clearly articulate words –> motor dysfunction affecting muscles used in speech
What are the two branches of memory?
Short term (including working memory) Long term
What are the two branches of long term memory?
Explicit (conscious)
Implicit (unconscious)
What is the two branches of Explicit long term memory
Episodic (events that happen to a person)
Semantic (general knowledge of the world)
What are the two branches of Implicit long term memory?
Priming (Stimulus A affects stimulus B)
Procedural (motor)
What is the entire bases of memory?
Synaptic plasticity
What does synaptic strength determine?
The affect on the post synaptic side and the generation of an action potential/affect there
How do synapses increase their synaptic strength?
More neurotransmitters released
Larger number of post-synaptic receptors
New formation of synapses
What is the importance of the temporal lobe in memory?
Partial retrograde and extreme anterograde amnesia for long term factual “declarative” memories
What is Retrograde amnesia?
When there is memory loss before the event/trauma
What is Anterograde amnesia?
Memory loss after event/trauma
What is the importance of sleep in memory consolidation?
Neuronal replay
What is the hippocampus required for in memory?
Forming long term memories –> especially declarative
What is the amygdala required for in memory?
Emotionally-coloured memories –> emotional charged memories are better preserved
Where are memories stored after they are formed?
Mainly in the association cortex
Why is it unlikely that memories are stored in particular discrete places?
Because like for thoughts they may be a result of activity of interactive neuronal networks
How does damage spread during Alzheimer’s disease?
Starts in the Temporal and prefrontal cortex –> continues along the base structures as well as the parietal lobes –> eventually spreads to all areas outer from the corpus callosum
What happens to the size and weight as people age?
Reduction in size and weight.
Narrower gyri
Wider sulci
Enlarged subarachnoid space
Do the number of neurons change as we age?
Yes –> they decrease
How does cerebral blood flow change with ageing?
Decreases
What are the anatomical changes of the brain with age linked to?
Less efficient neural processing
What is Dementia?
Cognitive impairment that interferes with the ability to function at work or at usual activities
- -> decreases of prior levels of functioning
- -> cognitive impairment not explained by delirium or major psychologic disorder
How is dementia diagnosed?
Combination of history taking from patient and a knowledgeable informant
Objective cognitive assessment
What is the prevalence of Dementia at >65 years?
Approx. 7%
What ranked killer is Alzheimer’s for women in Australia?
2nd
What can cause dementia?
Many diseases
How is Alzheimer’s disease characterised and what percentage of dementias does it account for?
Degenerative cerebral disease –> slow decline of cognition and function
- -> Driven by protein abnormalities (Plaques and NFT)
- -> Accounts for 60% of dementias
What is Parkinson’s disease and how many sufferers develop dementia?
Chronic neurodegenerative movement disorder
- -> Characterised by protein abnormalities (alpha- synuclein structures)
- -> Approx. 30% of patients will develop dementia
What is the second most common form of dementia after Alzheimer’s?
Vascular dementia –> problems of brain blood circulation
What does Dementia with Lewy bodies share similarities with?
Alzheimer’s and Parkinson’s disease
What are other diseases accounting for less than 5% of dementias?
Other degenerative diseases –> e.g. Huntington’s
Prion diseases –> e.g. Creutzfeldt-Jakob disease
What is the usual age onset of Alzheimer’s disease?
> 65 (95% of all cases)
What are the areas first affected in Alzheimer’s disease?
Entorhinal cortex
Hippocampus
What happens to cause Mild to moderate AD?
Cerebral cortex begins to shrink as more neurons stop functioning and die.
What happens in severe AD and what affects does this have on patients?
Extreme shrinkage occurs in the brain
Patients will be completely dependant on others for care
What impairments happen during Alzheimer’s disease?
Global cognitive impairment –> language, memory, visuospatial skills and personality changes
What do post-mortem tissue slicing immunohistochemistry show for AD?
Neurofibrillary tangles (p-tau) Senile/neuritic plaques (amyloid-beta)
Is the pattern of Alzheimer’s predictable?
Yes
How long does mild to moderate Alzheimer’s usually last?
2-10 years
How long can severe Alzheimer’s disease last?
1-5 years
What causes vascular dementia?
Problems in the blood supply to the brain
–> series of mini strokes leading to cognitive decline
How common is vascular dementia?
2nd most common after Alzheimer’s disease
What is commonly said about the progression of vascular dementia?
Step-wise –> as affects occur from distinct cerebrovascular events (huge drop and plateau)
What are the two kinds of vascular dementia?
- Multi-infarct dementia –> cortical strokes damaging regions of language, learning and memory
- Binswanger’s disease –> stroke related change to the white matter, hypertension and thickening of arteries
What is Parkinson’s disease clinically characterised by?
Motor symptoms –> rigidity, tremor, gait
Non motor symptoms –> mood disturbances, dementia
Difficulty starting voluntary movements –> opposing muscle groups do not relax
What is the potential pathology of Parkinson’s disease?
Alpha-synuclein aggregates form Lewy bodies in neuronal bodies and fibrils –> deposited in dopamine producing neurons
Excitatory neurons become more active
Substantia nigra (dopamine neurons that innervate the striatum) damage can give appearance of Parkinson’s disease
What co-occurs commonly with dementia with Lewy bodies?
Dementia –> with hallucinations and parkinsonism
Beginning with Parkinson’s disease and progressing to parkinsonian-dementia syndrome
What is Frontotemporal lobular dementia (FTLD)?
Progressive atrophy of frontal or temporal lobes of the brain
What are the 2 subtypes of Frontotemporal lobular dementia?
Behavioural variant–> (most common), loss of empathy, loss of inhibitions, difficulty reasoning, decline in self care
Progressive non-fluent aphasia –> ability to speak fluently is gradually lost, difficulty reading and spelling
Semantic dementia –> fluent but loss of meaning of words
What are the 3 types of protein inclusions identified in neurons and glial cells in FTLD?
Tau
TDP-43
Fused in sarcoma protein (FUS)
What are Tauopathies?
A group (over 20) of neurodegenerative diseases marked by a common feature of p-tau aggregates –> associated with synapse and neuronal loss
What causes Creutzfeldt Jakob Disease?
Prion disease
What are some symptoms of CJD?
Memory loss
Personality change
Hallucinations
Speech impairment
What is the average life expectancy of CJD?
1 year
What are the types of CJD?
Sporadic –> spontaneous misfolding (85% of all cases)
Familial –> 15% of all cases
Acquired –> 1% of cases from contaminated food
What changes happen in the brain from CJD?
Spongiform changes, neuronal loss, amyloid plaque in grey matter
Accumulation of PrP
What are tau?
Tau are proteins that help stabilise axonal microtubules
What causes tau protein related issues in Alzheimer’s disease?
Tau is regulated via phosphorylation
Hyperphosphorylation –> causes self assembly of tangles (neurofibrillary tangles)
These tangles have been found in affected areas in Alzheimer’s disease