43 - Memory Disorders Flashcards
HM treatment
Had serious, non-medication sensitive epilepsy (complex seizures of temporal lobe origin).
Treated with a bilateral medial temporal lobe resection.
Effect of removal of medial temporal lobe 1 2 3 4 5
1) Reduction in seizure frequency
2) Intellect and language function normal
3) Severe anterograde amnesia
4) Retrograde amnesia
- Approximately 11 years prior to surgery
5) Procedural memory and working memory intact
Priming
Subconscious learning ability.
Use briefly encountered memories to assist functioning.
Procedural memory
Long term, implicit memory. Skill acquisition (slow, automated)
Declarative memory divisions
Episodic and semantic
Episodic memory
Association between a personal event and a specific temporal, spatial and emotional context.
AKA Autobiographical memory
Semantic memory
General facts.
Not specific to the individual, is shared knowledge
Not contextual.
EG knowledge of general word meanings
Part of brain responsible for declarative memory
Hippocampal system (in medial temporal region)
Hippocampal anatomy
Look at slide.
Look at dentate gyrus
Material specificity of memory (assuming a left-dominant person)
Left hippocampus - Verbal memory (list learning, story recall)
Right hippocampus - Non-verbal memory (visuo-spatial associations, face recall)
Example of a secondary dementia
That brought on by chronic alcoholism.
What brings on memory disturbance from chronic alcoholism?
Thiamine deficiency (Korsakoff syndrome)
Common effect of sustained hypoxia of the brain
Memory loss (hippocampus is very sensitive to lack of oxygen)
Hippocampal sclerosis
1
2
3
1) Cell loss in hippocampus (CA1 particularly affected)
2) Gliosis (“scar tissue”)
3 )“Hardening of the hippocampus”
A leading cause of complex partial seizures
Hippocampal sclerosis
Treatment of complex partial seizures from hippocampal sclerosis
Remove sclerosed hippocampus.
Good success rate for decreasing seizures.
If hippocampus is sclerosed, probably not working properly anyway
Midline episodic memory structures 1 2 3 4 5
1) Basal forebrain
2) Anterior thalamus
3) Medial temporal region
4) Mammillary bodies
5) Retrosplenial cortex
Transient global amnesia 1 2 3 4 5
1) Precipitating events include: sexual intercourse, immersion in cold water, emotional stress
2) Striking anterograde amnesia
3) No disruption to ‘self-identity’
4) Underlying cause remains unknown – possibilities include vascular, migraine, epileptic event, drug effects.
5) Resolves. Happens for ~24 hours, then person goes back to normal
Post-traumatic amnesia
Associated with non-penetrating head trauma.
Transient amnesia.
Profound anterograde amnesia.
Often associated with aggression, agitation, poor sleep.
Most common cause of dementia
Alzheimer’s (~50% of dementias)
Mild cognitive impairment
Subclinical
Transition between normal ageing and dementia
Self-reported memory complaint (6 - 12 month history)
Objective memory impairment
Unaffected general cognitive functioning.
Normal capacity to perform activities of daily living
Conversion rate from mild cognitive impairment to Alzheimers
10 - 15% conversion to Alzheimer’s per year
Where does pathology begin in Alzheimer’s
Transenterhinal cortex ('gateway' into the hippocampus).
Stage I - II Alzheimer'sWhere does pathology localise in mid-stage Alzheimer’s?
Limbic system (entorhinal cortex)
Early memory complaints with Alzheimer’s
Poor name-face association.
Poor object-place association
Language impairment with Alzheimer’s
Dysnomia (can’t name things).
Fluent, empty language.
