Memory Problems

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Memory Problems

• Amnesia and More

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Case Study

• 66 year old mechanic suffered from an embolic
  infarct (stroke) affecting both medial temporal
  lobes, the left hippocampus
• Initial tests indicated severe anterograde and
  retrograde amnesia. Some difficulty naming
  certain objects and experiences
• He could talk, read, write,working memory in
  tact, could acquire new procedural skills

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How Do We Classify Memory Problems ?

• Typed of Problem - Disease (Viral Encephalitis /
  Alzheimers / Korsakoff), Trauma (concussion /
  stroke), Emotional (PTSS), or Neurochemical
• Localization -Brain structures involved in the
  problem (sometimes difficult to find)
• Functional Deficit - Location of the damage may
  be the same between subjects but the functional
  deficit may be different
• Difficulty in studying memory problems due to the
  high variability

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Memory Disorders

• Agnosias - deficits in recognizing familiar
  stimuli
• Aphasias - language deficits (alexia/reading,
  agraphia/writing)
• Apraxia - motor deficits (no disruption of motor
  pathways)
• Working Memory Disorders - resulting from
  injuries to the temporoparietal region of the
  frontal lobes
• Amnesia - usually a loss in explicit memory

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Agnosias

• Prosopagnosia - failure to recognize faces
• Damasio (1990) described a woman who could not
  recognize her familys faces or her own. She
  could recognize people through voices, hair
  color, eye color
• Semantic Agnosias - Doctor, Does a mouse have a
  beak? Subject, If I knew what a beak was I
  could tell you.
• Subjects episodic memory remained intact

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Agnosias

• Agnosias are not always uniform - one subject
  might have more difficulty with living than
  nonliving objects
• When asked to name objects in categories (land
  animals, water animals, birds, vegetables, fruit,
  body parts...) one subject showed an advantage of
  animal over food identification, another subject
  did better on foods, furniture, and body parts

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Working Memory Deficits

• Impairments of the phonological system have been
  observed in patients with lesions in the
  posterior left hemisphere (CT/MRI)
• Recall difficulty with spoken names, prices of
  goods seen on a label
• Performance is very poor on auditory and word
  span tests
• Is this a problem in the Phonological Store or
  the Articulitory Loop?

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Working Memory Deficits

• Sketchpad
• Subject sustained bilateral lesions in the
  temporo-occipital regions
• There was a clear dissociation on tests of
  spatial processing (mental rotation) and visual
  processing (color detection)

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Working Memory Deficits

• Damage to the frontal lobes may result in
  impairments of Executive Control
• Often shows Prospective Memory impairment -
  failing to remember to execute a task in response
  to an external cue or after a certain time has
  elapsed
• Failure to remember the frequency of occurrences
  of events in retaining spatial sequences and
  temporal order
• Failure to remember the source of the information

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Aphasias

• Wernickes - impairment in the comprehension of
  word elements
• Patients speak nonsense words. Phrase and
  sentence length, intonation and articulation are
  fine
• Can not read or understand auditory information
• Posterior Perisylvian region damage

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Aphasias

• Pure Word Deafness
• Cannot hear words. Patients are not deaf and can
  distinguish between nonverbal sounds
• Pure Word Blindness
• Person has no visual concept of lexical
  information
• Loses the ability to read (alexia)

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Agraphias

• Difficulty in writing
• Aphasic agraphia - many spelling and grammatical
  errors
• Constructional agraphia - words are formed
  clearly but wrongly arranged on the page
• Apraxic agraphia - can not form written letters

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Amnesic Disorders

• Include the loss of memories for past experience
  and of the ability for new learning
• These disorders are attributed (in part) to
  damage in the medial temporal lobe including the
  hippocampus, the diencephalon, and the basal
  forebrain

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Amnesic Syndrome

• Retrograde - involves impairment in the
  recollection of facts and episodes experienced
  before the injury/problem
• Anterograde - involves impairment of remembering
  new facts and episodes experienced after the
  injury
• Relatively spared functions may include memory
  for skills, implicit, semantic, and performance
  on such working memory tasks such as the digit
  span

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Retrograde Amnesia

• May include the loss of autobiographical,
  semantic, or general event memory
• Tests of autobiographical memory - asked to
  recall or is cued about such life periods, or
  themes such as school, friends, marriage
• Recollection failure is usually uniform across
  preceding decades
• Some times of information is lost while others
  are retained (i.e. forget family faces not famous
  faces)

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Anterograde Amnesia

• In mild brain damage, subjects tend to regain the
  ability to learn new information
• Learning problems may not be uniform across tasks
• Assessment - Wechsler Memory Scale (Subtests
  paired-associate, story, digit span, reproduce
  drawings)

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Though the study of memory deficits have an
important influence on theories of the brain,
there is still the problem of how the deficits
actually work
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Explaining Amnesia

• Input Theories - (Cermak) perhaps amnesiacs do
  not spontaneously encode material at a deep
  semantic level
• Found that Amnesiacs do show Levels of Processing
  Effects
• Faster Forgetting - learning would be normal
• (Hopper) found that amnesic and control patients
  forget at the same rate

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Explaining Amnesia

• Retrieval Deficit
• Interference Hypothesis - might have a great deal
  of interference
• Results showed no difference between controls and
  amnesiacs
• Contextual Hypothesis - might not be able to
  associate cues with learned information
• Related to source monitoring errors
• Still remains popular but not conclusive

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Memory Problems Due to Disease
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Alzheimers Disease

• Effects 45 of people over the age of 85
• The disease is progressive starting with minor
  memory loss to losing track of everyday
  activities, and failing to recognize friends and
  family. Also a deterioration of cognitive and
  emotional functions
• Due to a general degeneration of the brain
  resulting in atrophy and growth of plaques

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Alzheimers (Explicit Memory)

• Learning strategies do not have an effect (levels
  of processing, list organization). Also,
  retrieval cues do not help
• Autobiographical - a temporal gradient, with more
  recent memories more vulnerable than remote
  memories
• Word naming is poor, but there is a pattern.
  Errors suggest that the fine distinctions are
  affected and the abstract distinctions are spared

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Alzheimers (Explicit Memory)

• Patients tend to perform better in visual than in
  verbal semantic tasks
• Semantic organization seems to be in terms of
  concrete dimensions, such as size, rather than in
  terms of abstract attributes, such as domesticity

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Alzheimers (Working Memory)

• The Phonologic Loop are relatively well
  preserved. Show phonologic similarity and word
  length effects
• Not much known about the Sketchpad
• Executive dysfunction is the most noticeable.
  Thus, problems with deviled attention

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Alzheimers (Implicit Memory)

• Priming effects are still found in Alzheimers
  patients, though reduced
• Still have motor memory (skills), such as making
  a telephone call or coffee
• Still can learn procedural skills such as
  tracking a moving target in the pursuit rotor task

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What Have We Learned From Studying Memory
Disorders?

• Memory does not seem to be a unitary system.

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Memory in Older Adults (60)

• There is no question that memory declines with
  age
• In older age there is a decrease in the brain
  blood flow, oxygen and protein metabolism, and
  fewer neurotransmitters
• The question is - Why does memory decline
• Overall there is a great deal of speculation as
  to the locus of the problem

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Aging (encoding hypothesis)

• One idea is that older adults fail to encode
  environmental cueing information
• There is strong support for and against this idea
  (i.e. context usually helps younger adults
  remember words in a sentence, but not so in older
  adults - yes and no)
• Overall we can agree on the fact that older
  adults take longer to encode information compared
  to younger adults

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Aging (retrieval hypothesis)

• People are generaly better at recognition than
  they are at recall. However, recall problems are
  greater in older adults
• Overall, it seems that older adults have greater
  difficulty in rinstating the circumstances under
  which they acquired information. This is called
  sources forgetting (similar to ideas associated
  with amnesia)

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Aging (semantic memory)

• There does not seem to be any difference between
  younger and older adults in semantic memory
• Older adults do however, have more frequent
  tip-of-the-tongue occurances
• It is generally believed that this may be due to
  the cognitive slowing hypothesis

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Aging (implicit memory)

• Implicit memory is often related to memory for
  skills (driving, playing an instrument)
• Overall, there does not seem to be any decrease
  in implicit memory in older adults
• Ex. A study looking at younger and older piano
  players. There were no differences in number of
  errors, force applied to keys, or interkey
  intervals
• In fact older adults may use implicit memory more
  efficiently in order to compensate for slowing
  motor responses