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BHS 499-07 Memory and Amnesia

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