Neuropsychology%20of%20Memory

1
Neuropsychology of Memory

• Types of memory problems
• a pure amnesia is relatively rare
• memory problems commonly occur after a traumatic
  brain injury (TBI)
• TBI results in brain damage of two sorts
• lesions
• twisting and shearing of brain structures and
  damage from bony protuberances of brain,
  particularly of the temporal lobes

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Neuropsychology of Memory

• Memory problems following TBI
• post-traumatic amnesia
• retrograde amnesia
• anterograde amnesia

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Neuropsychology of Memory

• Memory problems following TBI
• post-traumatic amnesia
• after severe TBI, individuals typically lose
  consciousness
• after they begin to regain consciousness, there
  is often a gradual recovery during which patients
  have difficulty keeping tracking of and
  remembering ongoing events, though there may be
  islands of lucidity and memory

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Neuropsychology of Memory

• Memory problems following TBI
• retrograde amnesia
• refers to difficulty remembering events that
  occurred prior to injury
• the duration of amnesia varies but can extend
  back for several years
• duration of retrograde amnesia typically shrinks
  as time passes

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Neuropsychology of Memory

• retrograde amnesia
• duration of retrograde amnesia typically shrinks
  as time passes
• e.g., Russell (1959) described case of TBI as a
  result of a motorcycle accident
• 1 week post accident patient had lost 11 years of
  memory extending back from injury
• 2 weeks post accident patient had last 2 years of
  memory
• about 10 weeks post injury memories of the last
  two years gradually returned

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Neuropsychology of Memory

• Memory problems following TBI
• retrograde amnesia
• this pattern of results suggests that retrograde
  amnesia is a retrieval problem
• the pattern of damage/recovery -- from most
  distant to most recent -- has been argued by some
  to reflect a failure of consolidation (Ribots
  Law)

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Neuropsychology of Memory

• Memory problems following TBI
• retrograde amnesia
• formal testing of amnesics using famous
  faces/famous events has shown that there appears
  to be recall and recognition for old faces/events

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Neuropsychology of Memory

• retrograde amnesia
• Butters Cermak (1986) reported a case study of
  an eminent scientist (born 1914) who had written
  his autobiography only two years prior to
  becoming amnesic
• tested him by asking him questions all drawn from
  his autobiography

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Neuropsychology of Memory
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Neuropsychology of Memory

• retrograde amnesia
• the pattern of results in some individuals appear
  to depend upon the nature of the retrieval cue
  presented
• Warrington and McCarthy (1988) showed that an
  amnesic patient was impaired when shown faces of
  famous people and asked to recall them
• however, performance was normal when tested using
  recognition procedures

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Neuropsychology of Memory

• retrograde amnesia (RA)
• pattern of memory gradient varies across patients
  (See Moscovitch et al. 2006)
• If lesion restricted to hippocampus, RA extends
  back a few years only
• When lesion includes entire hippocampal formation
  or extends to adjacent regions, severe ungraded
  RA (ungraded means that memory loss is equivalent
  at all time periods since acquisition) some labs
  have reported graded retroactive amnesia (recent
  memories are poorer than more remote memories)

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Neuropsychology of Memory

• Memory problems following TBI
• anterograde amnesia
• refers to problems of learning new facts
• although sometimes amnesia is specific to
  learning of verbal material (following LHD) or
  visuo-spatial material (following RHD) amnesia
  usually affects learning of many types of new
  information

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Neuropsychology of Memory

• Amnesic syndrome
• dense form of memory deficit (as assessed by
  standardized testing)
• relatively spared performance in other domains

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Neuropsychology of Memory

• Causes of amnesia
• Korsakoffs syndrome drinking too much, eating
  too little, resulting in a thiamine deficiency
  and brain damage
• damage to brain following viral infection (e.g.,
  viral encephalitis)
• lesion to critical brain regions -- e.g., HM
• anoxia following heart attack, suicide attempt,
  etc.

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Neuropsychology of Memory

• Korsakoffs syndrome
• History
• 1881, a neurologist Carl Wernicke described a
  syndrome involving ataxia, oculomotor problems
  (gaze palsies and nystagmus), peripheral
  neuropathy, and confusion. This condition came
  to be known as Wernicke's encephalopathy
• Korsakoff identified several patients with
  confusion, confabulation, sensory loss
  (especially of the feet), and anterograde amnesia

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Neuropsychology of Memory

• Korsakoffs syndrome
• Terminology
• Ataxia problems of muscular coordination e.g.,
  people duck walk, feet apart, stiff-legged
• oculomotor problems (gaze palsies and
  nystagmus) abnormal eye movementspalsy
  paralysis nystagmus involuntary rapid eye
  movements
• peripheral neuropathy functional disturbance
  of peripheral nervous system

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Neuropsychology of Memory

• Korsakoffs syndrome
• History
• 1901 Bonhoffer realized Korsakoffs patients had
  passed through the Wernicke's encephalopathy
  stage
• today syndrome is called alcoholic Korsakoff
  syndrome. There are seven primary defining
  features of this disease

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Neuropsychology of Memory

• Defining features of alcoholic Korsakoff syndrome
• a. a retrograde amnesia with a temporal gradient
  (i.e., better preserved memories from the remote
  than from the more recent past)
• b. anterograde amnesia, meaning a nearly complete
  inability to learn new information from the time
  of the disease onset onward.

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Neuropsychology of Memory

• c. confabulation, which is a tendency to "fill in
  the gaps" of one's memories with plausible
  made-up stories.
• confabulations are rare among chronic Korsakoff
  patients who've had the disease for more than 5
  years. Patients in the chronic stage are more
  likely to say "I don't know" or remain silent
  when faced with memory failures rather than to
  invent stories.

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Neuropsychology of Memory

• d. generally preserved IQ, including a normal
  digit span.
• e. personality changes, the most common of which
  is apathy, passivity and indifference
• inability to formulate and follow through a
  series of plans
• f. lack of insight into their condition.
• How can someone with a shattered memory remember
  that he has become unable to remember?

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Neuropsychology of Memory

• Korsakoffs syndrome
• worst impairments are on episodic memory tests,
  including list learning of words, figures, or
  faces, paragraph recall.
• relatively preserved semantic memory, including
  normal verbal fluency, vocabulary, rules of
  syntax, and basic arithmetic operations
• intact sensori-motor memory (mirror tracing,
  mirror reading, pursuit rotor)
• intact performance on implicit memory tests

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Neuropsychology of Memory

• Neuropathology of Korsakoffs syndrome
• most sources attribute the amnesia to combined
  lesions in two diencephalic structures regions
  of the thalamus and the mammillary bodies of the
  hypothalamus

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Neuropsychology of Memory

• HM, Hippocampal man
• prototype of amnesia attributable to hippocampal
  damage
• bilateral mesial temporal lobe resection
  extending 8 cm. back from the temporal tips,
  including the uncus and amygdala, and destroying
  the anterior two-thirds of the hippocampus and
  hippocampal gyrus, for the treatment of
  intractable epilepsy in 1954.
• surgery led to a permanent, severe anterograde
  amnesia, limited retrograde amnesia, and normal
  intelligence.

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Neuropsychology of Memory

• HM, Hippocampal man
• Perceptual, motor, and cognitive functioning
• IQ above average language function intact,
  speech fluency slightly impaired spelling poor
• Appreciation of puns and linguistic ambiguities
• Difficulty with some spatial tasks (e.g., could
  not use spatial floor plan to navigate through a
  novel building, but could reproduce a floor plan
  of family home)

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Neuropsychology of Memory

• HM, Hippocampal man
• Memory
• Almost no capacity for new learning regardless of
  materials (short stories, word lists, pictures,
  etc.)
• But there are certain tasks requiring memory that
  are intact in H.M.
• Mirror drawing

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Neuropsychology of Memory

• Multiple memory systems perspective
• HM also has a retrograde amnesia that is, he
  forgets events that occurred prior to surgery
• His retrograde amnesia is temporally graded The
  closer the event to surgery the less likely he is
  able to recall it
• This finding suggests that the medial temporal
  lobes are not always required to retrieve
  memories (One possibility is that some process
  occurs that makes it possible to retrieve
  information that does not rely on medial temporal
  lobes)
• Long-term memory consists of all the different
  types of memory shown in the previous slide
• Explicit (declarative) memory refers to memory
  that can be declared or described to other people
• It includes episodic memory, memory for events in
  our personal past. Episodic memories are
  temporally dated, spatially located, and
  personally experience
• semantic memory, our general knowledge about
  things in the world

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Neuropsychology of Memory

• Multiple memory systems perspective
• In 1962 Milner and colleagues showed that HM
  improved on tasks requiring skilled movements
• HMs improvement was comparable to controls
• Skill was called mirror tracing because it
  requires participants to draw the outline of a
  star while looking at the reflection of his hand
  and the star on the mirror
• HM from had no conscious recollection of having
  done this task in the past
• This is now viewed as a form of non-declarative
  or implicit memory tasks

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H.M.s skilled learning performance
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Encoding and Retrieval from long-term memory (LTM)

• Multiple memory systems perspective
• Other forms of implicit memory include priming
  effects that were reported by Warrington
  Weiskrantz (1968)
• In this study amnesics shown list of words (e.g.,
  absent) at test participants were given word
  stem completion task (e.g., abs_____), and
  instructed to complete with first word that comes
  to mind
• Results showed that amnesics (and controls) were
  more likely to complete word stems with
  previously studied words

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Neuropsychology of Memory

• HM, Hippocampal man
• Gollins partial picture task
• Task involves recognition of fragmented line
  drawings of 20 objects
• 5 cards for each object with each card showing
  more and more fragments of the completed drawings
• Participants are shown the 20 most difficult
  cards, then the next-most-difficult cards etc.

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Neuropsychology of Memory

• HM, Hippocampal man
• Gollins partial picture task (Warrington
  Weiskrantz, 1968 Nature, 217, 972-974
• HM and normal controls performed this task, and
  then after an hour of intervening activity
  performed the task again
• Results shown in next figure show that H.M. and
  controls made fewer errors on immediate tests as
  figures became more complete and when tested
  after a 1 hour delay there was memory retention
• Conclusion. Perceptual memory is intact in H.M.
  perceptual memory does not appear to be mediated
  by medial temporal structures

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Neuropsychology of Memory

• HM, Hippocampal man
• Dot pattern study (Gabrieli, 1990,
  Neuropsychologia, 28, 417-427)
• H.M. and controls were shown a series of 5 dots
  arranged in a unique pattern
• Baseline draw. Participants (Ps) were instructed
  to draw any pattern they wanted (to control for
  pre-existing biases)
• Experiment. Ps were shown a target pattern
  copied that pattern on dots
• After 6 hour delay, Ps were shown dots and were
  instructed to draw on dots any pattern they
  wanted

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Neuropsychology of Memory

• HM, Hippocampal man
• Dot pattern study (Gabrieli, 1990,
  Neuropsychologia, 28, 417-427)
• Implicit memory percentage of target figures
  drawn that were identical to the copied target
  pattern (dots drawn in the baseline condition
  were not scored)
• Explicit memory Recognition memory Ps were
  shown 4 dot patterns that drawn on the dots and
  selected the dot pattern that had been copied

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Dot pattern

• Top figure shows dot pattern and target stimuli
• Left panel of bottom figure shows explicit
  performance and right panel shows implicit
  performance of H.M. and Controls

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Neuropsychology of Memory

• HM, Hippocampal man
• Dot pattern study (Gabrieli, 1990,
  Neuropsychologia, 28, 417-427)
• Implicit memory dot pattern priming equivalent
  for H.M. and controls
• Explicit memory H.M. impaired on recognition
  memory test compared to controls

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Neuropsychology of Memory

• HM, Hippocampal man
• Dot pattern study (Gabrieli, 1990,
  Neuropsychologia, 28, 417-427)
• Gabrieli and colleagues argued that this finding
  cannot be attributable to activation of a
  pre-existing memory (e.g., a semantic
  representation)
• Proposed that it is attributable to a type of
  perceptual priming, perhaps of a non-semantic
  structural description of a pattern

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Artificial grammar learning

• Amnesics can have intact capacity for learning
  certain cognitive skills
• E.g., artificial grammar such as shown in Figure
• Participants were shown novel letter strings one
  at a time and were asked to classify the strings
  as grammatical or nongrammatical

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Artificial grammar learning

• Participants were then tested to determine
  whether they could distinguish between
  grammatical and nongrammatical letter strings
• Results showed that amnesics and normal controls
  could classify correctly about two-thirds of the
  letter strings

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Artificial Grammar

• Top panel shows an example of an artificial
  grammar
• Bottom panel shows examples of grammatical and
  nongrammatical strings
• Knowlton et al. (1992). Psychological Science, 3,
  172-179

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Types of memory

• Declarative versus procedural memory What is
  different?
• Early ideas
• Amnesics have intact motor skills, but other
  types of memory are impaired false e.g.,
  because amnesics have intact perceptual learning
  (repetition primining)
• Amnesics intact memory for simple tasks false
  e.g., grammatical reasoning

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Types of memory

• Declarative versus procedural memory What is
  different?
• Early ideas
• Amnesics intact on tasks that involve slow,
  incremental learning, but impaired on quickly
  acquired tasks false e.g., repetition priming
  occurs after a single trial

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Types of memory

• Moscovitch (1984)
• Proposed that memory preserved in amnesia when
• 1. task structured so that its goal and means to
  achieve it are apparent
• 2. means to achieve at are in repertoire of
  participant
• 3. Success does not require memory for a
  particular event

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Types of memory

• Schacter explicit versus implicit memory
• Amnesics impaired on tasks that require explicit
  memory unimpaired on implicit memory tasks
• Explicit memory. Conscious recollection generated
  by direct access to memory
• E.g., what were the words on the list?
• Implicit memory. Unconscious changes in
  performance influenced by previous experience
• Note measures are indirect

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Types of memory

• Tulving episodic versus semantic memory
• Episodic memory representations of specific
  personal experiences episodic memories have a
  unique spatial/temporal context
• Semantic memory ones world knowledge memories
  that are not bound to a specific experience

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Types of memory

• Tulving episodic versus semantic memory
• Some evidence to suggest amnesics have spared
  semantic memories (acquired prior to neurological
  insult) e.g., K.C., HM
• Amnesic learning of new facts impaired
• Note semantic and episodic memories may be
  entangled
• E.g., when asked to recall a previous memory KC
  and HM were only able to recall general aspects
  of memory not the details

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Types of memory

• Tulving episodic versus semantic memory
• Summary episodic memory versus semantic memory
  distinguished on basis of content
• Episodic memory is autobiographical semantic
  memory is factual

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Types of memory

• Relational memory (Eichenbaum Cohen)
• Declarative memory is relational memories are
  related to each other
• Nondeclarative memories lack relational
  organization
• Episodic memory relational because events have
  spatial, temporal, as well as other relations
• Semantic memories are also relational because
  they represent associated facts about the world

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Types of memory

• Relational memory (Eichenbaum Cohen)
• Proposed that relational memories can be compared
  and contrasted
• Relational memories enable inferences and
  generalization

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Recognition memory dual-process models

• Several lines of evidence support the idea that
  two distinct processes (recollection,
  familiarity) mediated by different brain regions
  underlie recognition memory
• Example. See face of a person you recognize the
  person as familiar but are unable to recollect
  anything about the person, when or where you met
  that person
• Recollection you recognize that person and can
  recollect details about that person

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Recognition memory dual-process models

• Evidence for dual process models (behavioral)
• Speeded recognition tests have shown that item
  recognition tests (was this item studied) are
  made more quickly than associative recognition
  tests (when or where was this item studied)
• Analysis of confidence intervals has shown that
  when hit rate is plotted against false alarm
  rate, curves are different for associative
  recognition (linear) versus item recognition
  (curvilinear)
• also two different parameters are required to
  account for shape of curve suggesting that two
  distinctly different cognitive processes are
  operating

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Recognition memory dual-process models

• Evidence for dual process models (behavioral)
• Yonelinas has proposed that familiarity reflects
  the strength of the memory trace (an is
  quantitative)
• Recollection reflects retrieval of qualitative,
  contextual information

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Recognition memory dual-process models

• Evidence for dual process models (lesion)
• Amnesics are much more impaired on associative
  recognition tests than on item recognition tests
• Analysis of confidence intervals has shown that
  only 1 type of process (curvilinear) is required
  to account for recognition performance
• See Yonelinas (2002) for further details

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Imagining new experiences amnesic performance

• Imagining new experiences (Schacter, Maguire,
  Addis)
• Amnesic individuals are impaired in ability to
  imagine new experiences
• E.g., when asked to describe what they imagine
  when lying on a sandy beach, amnesic
  participants were only able to describe general
  aspects of this scenario (gist)
• Normal controls could describe in specific detail
  what they had imagined

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Neuropsychology of Memory

• Functional characteristics of amnesia
• working memory is intact
• semantic memory is spared (controversial)
• episodic memory is impaired
• procedural memory is intact

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Neuropsychology of Memory

• Theoretical implications of amnesia
• provides evidence for STM versus LTM distinction
• supports the notion that there are different
  systems mediating explicit (episodic) and
  implicit (procedural memory)
• may indicate that semantic and episodic memory
  can be fractionated
• may provide insight into nature of consciousness

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Neuropsychology of Memory

• Memory and Consciousness
• Tulving has proposed that different memory
  systems have associated with them different
  levels of consciousness
• noetic -- awareness
• episodic memory -- autonoetic, self awareness
• semantic memory -- noetic, aware of the
  information, but not aware of event
• procedural memory -- anoetic no conscious
  awareness

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Neuropsychology of Memory
Autonoetic
Episodic
Semantic
Noetic
Procedural
Anoetic
59
Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory
• what is common appears to be the circuit linking
  regions in the temporal lobes, the hippocampus,
  the mammiliary bodies and regions of the thalamus
  (note review Korsakoffs)
• Next slides will review this in more detail
• See Eichenbaum (2002). The cognitive neuroscience
  of memory and Moscovitch et al. (2005). 207,
  35-66. Journal of Anatomy

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61
Neuropsychology of Declarative Memory

• Medial temporal lobe structures viewed from the
  side (saggital section)
• Moscovitch et al. (2005)

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Recollective and familiarity memory systems
63
Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory
• 3 major component brain regions involved in
  declarative memory
• Cerebral cortex, parahippocampal region
• Hippocampus
• Parahippocampal region consists of perirhinal
  cortex, parahippocampal cortex, and entorhinal
  cortex

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Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory flow
  of information
• Bidirectional connections between cortex and
  parahippocampal region
• Bidirectional connections between parahippocampal
  region and hippocampus
• Highly processed information comes from
  association areas of the cortex
• Info further processed by the parahippocampal
  region and hippocampus before being projected
  back to regions that provided the information

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Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory flow
  of information
• Aside Background info about how sensory and
  motor processing makes its way to association
  areas
• Sensory info -gtprimary cortical areas (e.g.,
  visual cortex) -gt secondary and tertiary unimodal
  sensory regions -gt multimodal association areas
  located in temporal, parietal, and frontal lobes
  as well as in cingulate area

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Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory flow
  of information
• Aside Background info about how sensory and
  motor processing makes its way to association
  areas
• Motor -gtprimary cortical area (e.g., motor
  cortex) ultimately projects to prefrontal and
  cingulate areas

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Neuropsychology of Declarative Memory

• Brain regions mediating declarative memory flow
  of information
• Association areas of the temporal -- object
  identification using info from multiple sensory
  modalities
• Association areas parietal lobes process
  spatial info about visual and other sensory
  inputs
• Prefrontal and cingulate areas process info
  about the significance of stimuli, rules of
  tasks, and plans for tasks
• Each of these association areas provides input to
  the parahippocampal region

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Neuropsychology of Declarative Memory

• Parahippocampal region
• Consists of 3 distinct areas
• Perirhinal cortex
• Parahippocampal cortex
• Entorhinal cortex
• Inputs to parahippocampal region come from
  virtually every higher-order association area
• Perirhinal and parahippocampal cortices project
  to the parts of the entorhinal cortex

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Neuropsychology of Declarative Memory

• Parahippocampal region
• Anterior cortical inputs from prefrontal cortex
  and anterior cingulate project to the perirhinal
  cortex and entorhinal cortex
• Posterior cortical inputs (temporal and parietal
  regions) project to the perirhinal and
  parahippocampal cortices

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Neuropsychology of Declarative Memory

• Hippocampus
• Consists of several subfields including the
• CA1, CA3
• Dentate gyrus
• Subiculum
• Connected bidirectionally to the fornix, the
  prefrontal cortex and the parahippocampal region
• Also connected to regions of the thalamus
  (anterior)

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Neuropsychology of Declarative Memory

• Linking brain and memory
• Distinct memory systems reviewed in this lecture
  include
• Recollective memory conscious recollection of
  experiences (autonoetic)
• Familiarity memory memory for stimuli rather
  than for events stimuli are recognized as
  familiar wthout being placed in spatial/temporal
  context (noetic)
• Semantic memory memory for noncontextual
  content of experience or knowledge about the
  world (facts, concepts, word meanings, objects,
  tools etc.)
• It includes knowledge about ourselves (DOB, where
  we lived, our jobs, facts about family etc.

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Neuropsychology of Declarative Memory

• Linking brain and memory
• Recollective memory
• Relies on hippocampus, mamiliary bodies, and
  anterior thalamic nuclei via the fornix (see
  solid lines in Figure)
• Familiarity memory
• Relies on circuit involving perirhinal cortex and
  medial dorsal thalamus
• Damage to this circuit will impair recognition of
  even single items (see dotted lines in Figure)
• Parahippocampal cortex may mediate place memory

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Recollective and familiarity memory systems
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Neuropsychology of Declarative Memory

• Linking brain and memory
• Semantic memory
• Does not depend on medial temporal lobe and
  diencephalic structures
• Semantic memory relies on a network of anterior
  and posterior neocortical structures
• Precise structures depend upon attributes of
  memory (see next slidedifferent colors represent
  site of different memory attributes (e.g.,
  form, motion)
• Brain regions include lateral and anterior
  temporal lobe regions and the lateral inferior
  prefrontal cortex particularly in the left
  hemisphere (see next slide)

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Martin Chao (2001). Current Opinion in
Neurobiology

• (a) Ventral brain regions from occipital to
  temporal lobesrepresent color and shape
  properties (fusiform gyrus)
• (b) Left lateral areas motor areas in
  prefrontal cortex and parietal areas represent
  manipulation of objects posterior temporal lobes
  represent motion properties of objects

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Semantic Memory