memory disorders Flashcards
brain structures
- different types of memory involve different structures
- damage to hippocampus, poor episodic
- damage to para hippocampal cortex, poor semantic memory
- damage to both regions, poor episodic and semantic
causes of amnesia
- damage to different structures of the brain cause different syndromes
- causes:surgery, chronic alcohol abuse, brain tumour, dementia, bilateral stroke, closed head injury.
retrograde amnesia
- poor recall for memories formed before onset of amnesia
- greater for episodic than semantic
- temporal gradient, older memories less impaired
consolidation theory
- physiological process in the hippocampus leads to formation of long lasting memories
- consolidated memories stored elsewhere, protecting them from effects of hippocampal damage
semanticization
episodic memories become more like semantic memories over time= protected from the effects of damage
reduced learning opportunity
- episodic on a single learning experience= explains amnesia
- semantic memories depend of several learning experiences
anterograde amnesia
- loss of ability to form new memories after onset of amnesia
- results from damage to areas of the brain that are involved in forming new memories
- damage to hippocampus the main cause in most instances
- mammillary bodies and fornix also commonly involved
global amnesia
- moderate retrograde and severe antergrade
- results from lesions in medial temporal lobe, hippocampus
patient hm
- amnesic
- suffered from severe epilepsy from age 10
- at age 27 had surgery to remove entire medial temporal lobe
korsakoffs syndrome
- also known as diencephalic amnesia
- vitmain b1 deficiency from chronic alcoholism
- damage to mammillary bodies in hypothalamus
- poor ability to remember events before or after onset amnesia
- some new learning ability, motor skills
- slight impairment of stm, digit span
symptomology
- typically has a gradual onset
-Brain damage widespread (hippocampus and frontal) - a precise pattern of damage varies across
-brain plasticity and learning of compensatory strategies
issues
- events happened before or after amnesia onset?
-damage to frontal lobe = other cognitive deficits
difficult to generalise across patients
does not provide a direct assessment of the impact of brain damage on ltm
semantic dementia
- severe problems with semantic memory but intact episodic
- severe loss of info about meanings of words and concepts
- difficulty naming pictures/pbjects, single comprehension, categorising and knowing uses and features of objects
- episodic memory and most executive functions reasonably intact in the early stages.
- patient differ in symptoms
- always involves degeneration of anterior temporal lobe
double dissociation
- amnesia and semantic dementia point to a double dissociation in ltm
- identify that brain damage to one structure disrupts one cognitive process (x) but not another (y)
- also identify brain damage to different structure disrupts cognitive process y but not x
amnesia=hippocampus
- poor episodic (x)
- intact semantic (y)
semantic dementia= anterior temporal lobe
- poor semantic
- intact episodic
dissociation
identification of a brain region responsible for cognitive process
single dissociation
brain damage to one structure disrupts one cognitive processes (x) but not (Y)
eyewitness testimony
- accuracy of an individuals memory is sometimes of enormous importance
- you are sole witness to a serious crime
- you have to identify perpertrator in a line up,used as evidence
Misinformation effect
Refers to the finding that memories are easily distorted by misleading information presented afterward.
confirmation bias
Tendency to recall information in a way that confirms pre-existing beliefs.
