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BHS 499-07 Memory and Amnesia
Memory Disorders
Influences on Memory
Alcohol – Bits & PiecesStress -- Kolb & Whishaw Seg 32 (CD 2)Diabetes – Kolb & Whishaw Ch 13 Seg 6 (CD 3)
Kinds of Memory Disorders
Organic – having a physical causeFunctional – having a psychological causeDys (as a prefix) means difficulty or limited ability to perform.A (as a prefix) means complete inability or lack of a function.
Alcohol & Memory
Alcoholic amnesia – alcohol prevents consolidation so nothing is remembered and no memory can be recovered.Alcoholic blackout – state-dependent memory, so recall is possible if one is back in the same state.Because many crimes are committed while drunk, memory failure is frequently blamed on alcohol.
Sleep & Memory
New sleep studies suggest a "memory life-cycle” with three stages - stabilization, consolidation, and re-consolidation.• Initial stabilization takes up to 6 hours.• Sleep needed for consolidation, deep non-REM• Alcohol disrupts consolidation
Sleep deprivation produces affects similar to aging.• Procedural memory and recognition memory are most
strongly affected.
Sources of Organic Dysfunction
Accident• Car accidents and other injuries (e.g., N.A.)• War
Disease• Encephalitis (viral) – inflammation of the lining
of the brain, causing swelling.• Stroke• Alzheimer’s disease• Korsakov’s syndrome (prolonged alcoholism)
Alzheimer’s Disease
A fatal degenerative disease caused by cell failure – neurofibrillary tangles and plaques that interfere with cell function.• All areas of the brain are eventually affected,
but frontal lobes and memory go first.
Confusions and memory problems do not resemble normal aging, amnesia or other memory problems.
Classification of Disorders
See Parkin, Ch 5, for tests used to assess memory problems.Disorders classified by type of symptom:• Generalizing – confusion, fuzziness, mental
slowing.• Localizing – few generalizing symptoms but
impairment of specific functions.Clusters of symptoms are a syndrome.• Concern about symptoms is a symptom itself.
Frontal Lobe Deficits
Confabulation – production of a false memory.• Momentary confabulation – responses that
could be correct.• Fantastic confabulation – responses clearly
fictional.Source amnesia – fact is remembered but not the source.Memory of temporal order.
Frontal Lobe Deficits (Cont.)
Impaired recall – more “ugly stepsisters,”no categorization.Metamemory is impaired, including FOK judgments and monitoring of search.False recognization:• Increased false alarms• Increased intrusions
Frontal Lobe Deficits (Cont.)
Faulty encoding and poor representation may be a cause of poorly focused search.• Information is needed to guide search.
The left frontal lobe guides encoding.The right frontal lobe guides retrieval.
Frontal Lobe Deficits (Cont.)
Emotional deficits:• Cognitive apathy, lack of motivation• Flattened affect
Impaired awareness of memory loss:• Inaccurate assessment of performance• Lack of distress
If confabulations are believed by others, no feedback on normalcy.
Alien Hand (Anarchic Hand) Syndrome – a Frontal Lobe Deficit
Peter Sellars in “Dr. Strangelove: or How I learned to story worrying and love the bomb”
Damage to the Parietal Association Cortex
Confusion about directions, inability to use words describing spatial relations:• Under, up, down
Inability to name body parts or point to parts of the body.Capgras syndrome (rt. Posterior parietal) inability to recognize close family members• Sometimes animals or even furniture• Invasion of the body snatchers
Reading & Writing Disorders
Alexia – inability to readAgraphia – inability to writeCaused by damage to the left angular gyrus which integrates information from the sensory modalities.
Pure Word Deafness
A person can hear and speak, read and write normally but cannot understand speech.Occurs with bilateral destruction of the auditory cortex or disconnection from Wernicke’s area.Because Wernicke’s area is not damaged, speech producted is OK.
Perceptual Deficits
Aphasia – involves inability to name something.Agnosia – involves inability to recognize something.Visual agnosias – inability to combine individual visual impressions into complete patterns.
Types of Visual Agnosias
Object agnosia – inability to recognize common objects.Prosopagnosia – inability to recognize faces.Color agnosias:• Achromatopsia (cortical color blindness)• Color anomia – inability to name colors.• Color agnosia – inability to recognize colors
Other Agnosias
Amusia – tone deafness, melody deafness, disorders of rhythm, measure, tempo.Astereoagnosia – inability to recognize the nature of an object by touch.Asomatoagnosia – knowledge of one’s own body.• Indifference to illness, asymbolia for pain
Pure Anomia
Loss of memory of words (anomic aphasia)• Cannot name pictures of common objects• Difficulty reading and writing
Produced by damage to either Broca’s or Wernicke’s area (fluent anomia).Use circumlocutions to get around missing words.
Broca’s Aphasia
Broca’s area may contain memories of the movements needed to produce speech.Produces three deficits:• Anomia – word-finding difficulty• Agrammatism – loss of grammatical construction• Difficulty with articulation
Slow, laborious, nonfluent speech without function words with with content words.
Conduction Aphasia
Disruption of verbal short term memory due to damage to the subcortical axons that connect Broca & Wernicke’s areas.Results in poor repetition – only meaningful words can be repeated (through other means).• Non-words cannot be repeated (blaynge).
Amnesic Syndrome
Short term memory is intact (unimpaired)Anterograde amnesia present affecting both recognition and recall tasks.Retrograde amnesia present, but extent varies.Semantic memory largely intact but can be affected by antero & retro amnesias.Procedural memory is intact.
Causes of Amnesic Syndrome
Damage to:• Hippocampus• Temporal cortex• Diencephalon (especially mamillary bodies)
Herpes simplex encephalitisKorsakoff’s syndrome (thiamine deficiency plus chronic alcoholism)Direct injury (H.M., N.A.)
Anterograde Amnesia
No new declarative information can be added to long-term memoryEvents from the present are quickly forgottenUsually accompanied by retrograde amnesia.Performance on IQ tests is unimpaired because it relies on info learned in past.
Retrograde Amnesia
Declarative information from the past is forgotten.Information is forgotten in a temporal gradient (based on time):• Ribot’s law – newer information forgotten first.• Both semantic and episodic information show this
gradient.
Difficult to test due to differences in life experiences, impairment varies.
Focal Retrograde Amnesia
Loss of remote memory unaccompanied by anterograde amnesia.May occur when the temporal cortex is damaged but not the hippocampus.Cases reported without head injury and with loss of procedural memory are probably malingering (faking).
Evidence for Implicit Memory
Alzheimer’s patients show impaired priming.Huntington’s Chorea patients show normal priming but impaired procedural memory.Procedural memory and priming are spared by amnesia.
