Executive processes

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Executive processes

• Properties of executive processes
• Executive processes coordinate mental activity so
  that a particular goal is achieved
• They do this by modulating the operation of other
  processes (modulate to guide or modify)
  however, executive processes do not actually
  carry out these activities

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Executive processes

• Different types of executive processes
• Several different types of executive processes
  have been identified. There is currently
  controversy about whether there are several types
  of executive processes or a single type (we are
  assuming several)
• 1. selective attention. (sometimes called
  executive attention (sustained attention) this
  type of attention is believed to act on the
  contents of working memory and directs future
  mental activity in order to achieve a goal (e.g.,
  driver focuses on traffic signs in order to take
  correct exit)
• 2. switching attention switching attention from
  one activity to another (e.g., having a
  conversation and driving)
• Inhibiting information that has been perceived
  (e.g., ignoring music on radio when traffic is
  heavy and one is driving)
• Scheduling a sequence of activities planning
  the order in which a activities will be carried
  out in order to achieve goal(s) (e.g., order in
  which you will pick up groceries, dry cleaning,
  medications)
• Performance monitoring review performance to
  ensure it is acceptable (e.g., checking speed
  limit while driving)

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Executive processes

• It is generally agreed that the frontal lobes
  play an important role when executive functions
  are carried out
• The frontal executive hypothesis proposes that
  executive processes are primarily mediated by the
  prefrontal cortex (PFC)
• PFC anterior to motor cortex (and for some
  authors the premotor cortex)
• PFC includes dorsolateral PFC, anterior
  cingulate, Brocas area, and the medial and
  orbital regions of the frontal lobes

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Executive processes

• Frontal lobes
• Prefrontal cortex massive network that links the
  motor, perceptual, and limbic (emotional network)
  regions
• Limbic system include amygdala, cingulate gyrus,
  orbitofrontal cortex and parts of basal ganglia

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Executive functions
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Executive functions

• Frontal lobe
• Major subdivisions of prefrontal cortex lateral
  prefrontal cortex, ventromedial prefrontal
  cortex, and anterior cingulate

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Executive processes

• Frontal lobes
• About third of cerebral cortex in humans frontal
  lobes are much larger in humans and are much
  larger than in other mammals, especially its
  anterior aspect
• Frontal lobes separated from parietal lobes by
  central sulcus and from temporal lobes by lateral
  sulcus

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Kolb Whishaw frontal lobe figure

• Lateral area 6 premotor cortex
• Medial area 6 supplementary motor cortex
• Area 8 frontal eye field

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Executive processes

• Dorsolateral prefrontal cortex (areas 9 and 46)
• Medial frontal cortex (areas 25 and 32)
• Inferior (ventral) prefrontal cortex (areas 11,
  12, 13, and 14) also called orbitofrontal cortex

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Executive processes

• Anatomical properties of PFC that are crucial for
  executive processing
• Perceptual, motor, cortical, and subcortical
  brain structures project to PFC
• This makes it possible to combine information
  from diverse sources, thereby enabling complex
  behavior
• PFC has multiple projections to multiple brain
  structures
• This permits it to modulate (exert top-down
  guidance) on other neural processes

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Executive processes

• Working memory and lateral prefrontal cortex
• A previous lecture discuss working memory
• Baddeleys model of working memory was presented

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Baddeleys working memory model
Visuo-spatial sketchpad
Phonological loop
Central Executive
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Executive processes

• Content-based model of working memory
• This is known as a content-based model of working
  memory because it assumes that different systems
  represent different content
• Phonological stores linguistic info and
  visusospatial represents visual and spatial
  information
• Model based on behavioral data reviewed in prior
  lecture

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Executive processes

• Process-based models of working memory
• It has been hypothesized that different regions
  of the PFC are recruited to carry out different
  tasks
• In other words different processes are associated
  with different brain regions

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Executive processes

• Different types of working memory
• In some tasks a participant is presented a
  stimulus, then is required to internally maintain
  a representation of that stimulus, until a probe
  is presented (maintenance condition)
• In an n-back task the participant is required to
  keep in mind a stream of stimuli and respond only
  if the stimulus was presented n-back
• Requires maintenance manipulation

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Executive functions

• Illustration of n-back task
• Note, the need to maintain information in memory
  and manipulate it

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Executive processes

• DEsposito et al. (1998)
• Meta-analysis
• DEsposito and colleagues performed a
  meta-analysis to investigate content-based and
  process-based accounts of working memory
• meta-analysis quantitative review of findings
  from several studies

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Executive processes

• DEsposito et al. (1998)
• One might expect based on the content account of
  working memory that the phonological loop might
  be left lateralized and the spatial sketchpad
  should be right lateralized as it is for
  perception
• To investigate this possibility DEsposito
  categorized studies based on their content
  (spatial, nonspatial)

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Executive processes

• DEsposito et al. (1998)
• Results support the hypothesis that spatial tasks
  tend to be associated with activation of the
  right prefrontal cortex, whereas nonspatial tasks
  are associated with activation of the left
  prefrontal cortex
• However, there was bilateral activation in many
  studies
• See top panel

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DEsposito et al. (1998)

• Top panel shows active foci for spatial and
  nonspatial tasks (content)
• Bottom panel shows active foci for maintenance
  and maintenance tasks

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Executive processes

• DEsposito et al. (1998)
• to investigate the process-based account of
  working memory, tasks were categorized as
  requiring maintenance or maintenance plus
  (maintenance manipulation)
• Results showed that tasks requiring maintenance
  plus had more dorsolateral activation
• See bottom panel

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DEsposito et al. (1998)

• Top panel shows active foci for spatial and
  nonspatial tasks (content)
• Bottom panel shows active foci for maintenance
  and maintenance tasks

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Executive functions

• Stroop test
• This test assesses the ability to maintain a goal
  and ignore/suppress habitual (prepotent)
  responses

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Executive functions

• Stroop effect demonstration
• in this next slide I want you to name the ink
  colours of the words as rapidly as possible

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Stroop (slide 1)

• red yellow blue red
• green red yellow green
• blue green red yellow
• red green red yellow

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Executive functions

• Stroop effect demonstration
• in this next slide I want you to name the ink
  colours of the words as rapidly as possible

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Stroop (slide 2)

• red yellow blue red
• green red yellow green
• blue green red yellow
• red green red yellow

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Executive functions

• Stroop effect demonstration
• in this next slide I want you to name the ink
  colours of the colour patches as rapidly as
  possible

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Stroop (slide 3)
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Executive functions

• Stroop effect
• The increase in time it takes to name of color
  when the word name does not match the color
  versus naming color patches is called the
  color-word interference effect (slide 1
  time/slide 3 slide)
• Note different versions of the Stroop assess
  interference in slightly different ways

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Executive functions
Age Dot time (DT) M (SD) Color word time (CWT) M (SD) Interference CWT/DT Errors Color word M (SD)
18-39 11.0 (2.5) 22.1 (7.2) 2.0 (0.6) 0.8 (1.0)
75-74 13.3 (3.6) 32.6 (9.6) 2.6 (0.9) 0.6 (1.2)
Dot time name dot color color word time name
word color
DT Name color of dot CWT Name color of word
designating color
Troyer, Leach, Strauss (2006), 13, 20-35
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Executive functions

• Stroop effect
• Age effects age significantly increases the
  magnitude of the interference effect
• Gender differences are not always present in the
  interference score
• The higher the IQ score the lower the
  interference effect

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Executive functions

• Stroop effect
• Standard interpretation of Stroop participant
  must selectively attend to the name of the ink
  color and ignore the word name (of a color)

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Executive functions

• Wisconsin Card Sort
• Used to assess for frontal lobe damage
• 4 stimulus cards are arranged in front of a
  participant cards vary on 3 dimensions shape,
  color, number
• Participants are given a deck of cards and must
  match each card with 1 of the stimulus cards, but
  are not told on which dimension they are matching
• Participants are told right or wrong

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Executive functions
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Executive functions

• Participants are given a deck of cards and must
  match each card to 1 of the 4 stimulus cards
• Participants guess at first, but since they are
  given feedback, they learn the correct attribute
• After sorting about 10 cards correctly, the
  examiner changes the attribute without warning
• Normal participants soon figure out correct
  attribute for sorting

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Executive functions

• Frontal lobe patients and normal participants do
  not differ in learning first critical trial, but
  they differ in the ability to switch attributes
• Normal participants switch after a few trials of
  negative feedback frontal lobe patients are less
  able to switch

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Executive functions

• Executive attention is needed whenever multiple
  representations in working memory or multiple
  processes are competing for control of behavior
  and thought
• In Stroop task there is competition, but this
  sort of competition is a feature of a broad range
  of tasks
• E.g., it has been shown that naming the color of
  a picture of a banana is slowed when it is not
  yellow (e.g., red)
• in general when there is an incompatibility
  between an automatic response and a correct
  response you get Stroop-like effects

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Executive functions

• Stimulus response compatibility exists when the
  response required is compatible with the way
  people would naturally respond to that stimulus
• E.g., high pitch respond up low pitch
  respond down
• E.g., stimulus presented on left or right side of
  display requires a response on same side as
  stimulus was presented

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Executive functions

• Stimulus response compatibility is strong and is
  observed even when position of object is
  irrelevant to response (Simon, 1990)
• E.g., suppose task is to make a right-handed
  response when a circle is presented and a
  left-handed response to a triangle reaction time
  is faster when the circle or triangle is
  presented on the side of the response
• Interpretation when there is an automatic
  connection between a stimulus and a response,
  little executive attention is required
• when 2 sources of information are incompatible,
  attention must be paid in order to focus on the
  relevant information and inhibit/ignore the
  irrelevant information

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Executive functions

• Cohen and colleagues have developed a neural
  network model of Stroop task
• It proposes that in addition to initial visual
  perceptual processing of color (occipital lobes)
  and visual words (temporal lobes), two additional
  attentional processes are required

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Executive functions

• Stroop effect demonstration
• in this next slide I want you to name the ink
  colours of the words as rapidly as possible

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Executive functions

• 1. attention controller
• This process keeps track of the task goal this
  is necessary because during incompatible trials
  in the color word condition, the name of the
  color font and the name of the word, which
  designates a color are two competing responses
• In the color-word condition it does this by
  activating more strongly the processes associated
  with the task goal (in this case the color of the
  word)

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Executive functions

• 2. conflict monitor
• This process monitors the amount of conflict
  between potential responses. When there is more
  conflict as there would be in the word-colour
  condition, the conflict monitor increases
  executive attention

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Executive functions

• Stroop effect
• Other points neuroimaging and lesion studies
  are consistent with hypothesis that frontal lobes
  are associated with Stroop
• Data also suggest that performance is mediated by
  a more broadly based system

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Executive functions

• Neuroimaging evidence
• Jonides and colleagues (2002) performed a
  meta-analysis of Stroop studies and related
  studies
• Results showed that the anterior cingulate and
  dorsolateral PFC were activated this is
  consistent with theory because it is known from
  other research that the anterior cingulate is
  activated mediates conflict and the dorsolateral
  PFC is involved in executive attention

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Executive processes

• Executive processes effects on longer-term
  memory
• Individuals with PFC damage may be impaired in
  their ability to organize temporally events in
  memory
• Milner (1995) performed a recency experiment in
  which participants were required to discriminate
  which of two events was presented more recently

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Executive processes

• Memory for temporal order Milner (1995)
• Participants were presented pairs of stimuli
  (e.g., 2 pictures of objects)
• Every so often a probe card is presented with ?
• Task to choose picture with more recently
  presented object

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Executive processes

• Milner (1995) Memory for temporal order
• Experimental condition both objects had been
  presented previously
• Control condition one picture presented
  previously one picture new (Recognition test)

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Executive processes

• Memory for temporal order Milner (1995)
• 3 groups of participants were tested
• Controls
• Unilateral damage to dorsolateral PFC px
• Unilateral damage to temporal px
• Px underwent surgery for relief from focal
  epilepsy

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Milner recency discrimination experiment

• Top panel shows stimuli used in expt
• Bottom panel shows that PFC participants were
  impaired relative to other 2 groups on recency
  discrimination test but not on recognition test

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Executive processes

• Memory for temporal order Milner (1995)
• Other findings this experiment was also
  performed with word stimuli
• Results showed that the effect was lateralized
• Patients with LHD were more impaired on recency
  discrimination when words were used, whereas px
  with RHD were more impaired with pictures

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Executive functions

• Memory for temporal order
• Milner et al. (1991) performed an experiment in
  which frontal and parietal patients were shown
  pairs of items
• Occasionally the pairs had a question mark
  between them
• Participants task was to decide which item had
  been presented more recently
• When only 1 item had been actually presented the
  test was an item recognition test
• When both items had been presented, the test
  requires order (and item) information

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Executive functions

• Memory for temporal order
• Patients with frontal lobe damage were impaired
  in their memory for order but not item
  information
• Patients with parietal lobe damage were impaired
  in their memory for item but not order information

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Executive processes

• Memory for temporal order Self-ordered pointing
• Keeping track of previous experienced events
  (memory for temporal order) has been examined
  using a self-ordered pointing task
• In this task participant is presented n card with
  n objects depicted on it
• The same objects are present on each card but
  their order is scrambled from card to card

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Executive processes

• Memory for temporal order Self-ordered pointing
• Task of participant is to point to the a
  different object on each card (one that hasnt
  yet been pointed to)
• Results
• Frontal lobe patients made more errors than
  controls discrepency between 2 groups increased
  with n, the number of objects and cards

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Executive processes

• Source memory
• Source memory refers to when we learned a fact or
  the context in which a fact was learned e.g.,
  who told you fact or in what context you viewed a
  face
• Source memory appears to require frontal lobe
  function

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Executive processes

• Source memory
• Janowsky, Shimamura, Squire (1999)
• In this experiment participants were taught new
  facts (e.g., The name of the dog on the cracker
  box is Bingo)

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Executive processes

• Source memory
• Janowsky, Shimamura, Squire (1999)
• 6-8 days later participants were asked to answer
  questions about these newly learned facts and
  other facts that might have been acquired outside
  of the experiment if they recalled the fact they
  were asked questions about when they learned the
  fact (during the previous session or reading,
  school etc.)

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Executive processes

• Source memory
• Janowsky, Shimamura, Squire (1999)
• Results
• Controls and frontal lobe patients did not differ
  in recall of facts
• Frontal lobe participants were impaired in recall
  of source of facts

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Executive processes

• Source memory
• Glisky et al. (1995)
• Investigated role of memory and executive
  function on item and source memory
• Neuropsychological tests assessed memory
  (temporal) and executive (frontal) function
• Performance on these two types of tests was
  weakly correlated

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Executive processes

• Source memory
• Glisky et al. (1995)
• Study participants heard sentences describing
  events (e.g., The boy went to the store to buy
  apples and oranges)
• Half were read aloud in mans voice and half in a
  womans voice

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Executive processes

• Source memory
• Glisky et al. (1995)
• Memory test
• Item memory recognition test in which pairs of
  studied and unstudied sentences were presented
  together
• Source memory participant heard sentence read
  aloud in a man or womans voice and decided which
  voice matched the studied sentence

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Executive processes

• Source memory
• Glisky et al. (1995)
• Results
• Controls and frontal lobe patients did not differ
  in recall of facts
• Frontal lobe participants were impaired in recall
  of source of facts

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Glisky (1995)

• Source memory relatively more impaired than item
  memory by low frontal function
• Item memory relatively more impaired than source
  memory by low temporal function

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Executive processes

• Executive processes effects on longer-term
  memory
• Individuals with PFC damage may be impaired in
  their ability to organize temporally events in
  memory
• Milner (1995) performed a recency experiment in
  which participants were required to discriminate
  which of two events was presented more recently

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Executive functions

• Sequencing
• Many activities of everyday living require people
  to plan and then carry out a sequence of
  activities, which must satisfy certain
  requirements in order to achieve a goal
• Studies have shown that patients with PFC damage
  are impaired on certain sequencing activities,
  but not all sequencing activities

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Executive functions

• Sequencing how is temporal order coded?
• An important component of sequencing is coding
  temporal order of events
• Evidence suggests that there are several
  different ways in which temporal order might be
  coded and that the coding of temporal order often
  involves separate processes from the coding of
  item information

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Executive functions

• Sequencing how is temporal order coded?
• An important component of sequencing is coding
  temporal order of events
• Evidence suggests that there are several
  different ways in which temporal order might be
  coded and that the coding of temporal order often
  involves separate processes from the coding of
  item information

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Executive functions

• Sequencing how is temporal order coded?
• Sternberg, (1966, 1967) compared performance on
  an item recognition (was letter presented?) and
  an order task (what is the next letter?)
• Item recognition memory set (BGRD) probe (g)
  response (yes)
• Order task -- memory set (BGRD) probe (g)
  response (r)

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Sternberg, (1966,1967)
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Executive functions

• Sequencing how is temporal order coded?
• Sternberg, (1966, 1967)
• note the large slope differences between the two
  tasks
• Results suggest that different processes are
  involved item and order tasks one difficulty
  with experiment is that one task requires
  recognition while the other requires recall
  however, many studies are consistent with the
  idea that item and order information are stored
  and processed differently

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Executive functions

• Sequencing how is temporal order coded?
• For example, there is evidence to suggest that
  memory for order information (information about
  associations) depends critically upon the
  hippocampus, but item information can be carried
  out independently of the hippocampus
• There is also evidence indicating that sequential
  information can be stored and processed in a
  variety of ways

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Executive functions

• Sequencing how is temporal order coded?
• There are many ways to code temporal order and
  there is evidence for each of these ways
  depending upon the task and other factors
• 1. Associative e.g., X R C B L code as X
  precedes R R precedes C C precedes L etc.
• 2. order tags e.g., X R C B L code as X is
  first R is second C is third, etc.
• 3. familiarity e.g., a form of representation
  in which strength or familiarity of item is
  continuously represented, so more recent items
  are stronger than earlier items, allowing
  participants to make a judgement on that basis
  (e.g., B is stronger then C)

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Executive functions

• Sequencing related items
• In many everyday situations, sequences of actions
  are related to each other, and in many cases have
  been performed several times in the past
• E.g., eating out typically involves being
  greeted, taken to a table, ordering a meal,
  eating, getting a bill, paying, and leaving
  (Schank Abelson, 1977)
• It is also possible to generate a novel script
  (e.g., opening a beauty salon)

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Executive functions

• Sequencing related items
• Sirigu et al. (1985) performed an experiment in
  which patients with PFC damage, damage to the
  posterior cortex, and normal controls were tested
  on familiar and novel scripts
• Participants were asked to generate familiar
  (going to a restaurant) and novel (opening a
  beauty salon) actions and then they were asked to
  order the actions into correct sequences

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Executive functions

• Sequencing related items
• No significance difference in the number or type
  of actions generated
• Individuals with PFC damage made more errors than
  other 2 groups when asked to order generated
  actions in correct sequence and the pattern was
  amplified with novel scripts
• Similar findings were obtained when the different
  groups were given cards with actions for scripts
  written on them

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Executive functions

• Brain imaging studies
• Buckner Wheeler (2001) reviewed findings from
  neuroimaging of remembering
• Several studies have shown consistently with a
  variety of stimuli (words, faces, pictures) that
  during memory recall the dorsolateral prefrontal
  cortex and the anterior frontal-polar cortex are
  activated

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Executive functions

• Brain imaging studies
• e.g., Buckner et al. (1995)
• Participants studied a list of words (couple,
  string)
• At test, during imaging, participants were shown
  the beginning of the word and were intstructed to
  recall the word (e.g., cou---, stri---- )
• Results on next slide illustrate the pattern of
  activation

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Buckner et al. (2001)

• Typical pattern of activation during recall of
  studied material blue, dorsolateral (BA 44/6)
  green anterior frontal-polar (BA 10)

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Buckner et al. (2001)

• 2 brain regions appear to have distinct
  functional properties
• Selectivity of anterior suggests it may have a
  specific memory function late onset consistent
  strategic retrieval/monitoring

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Executive functions

• Memory retrieval success
• Evidence that MTL and PFC involved during memory
  retrieval, but are there additional regions?
• Habib and Lepage (1999) meta-analysis
• compared activation of old and new items
• Results showed that a network consisting of left
  parietal cortex, left anterior frontal lobe (near
  frontal-polar region) responded more to old items
  (i.e., retrieval success)
• This finding has been replicated in more recent
  studies with a variety of materials

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Buckner et al. (2001)

• Panel a. paradigm
• Expt in which activation of old versus new items
  is compared

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Buckner et al. (2001)

• Panel b.
• fMRI imaging show differential activation of
  brain regions associated with retrieval of
  success note left parietal cortex activation
  (green arrow)

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Buckner et al. (2001)

• Panel c.
• Event-related potential (ERP) shows a rapid
  positive waveform that develops over left
  parietal sites during remembered old items (red)
  as compared to new items (green)

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Executive functions

• Spontaneous confabulations
• Individuals, who spontaneously confabulate have
  also been used to investigate role of the frontal
  lobes and executive function in memory
• Spontaeous confabulation statements are actions
  that reflect unintentional but obvious
  distortions of memory
• honest lying
• Spontaeous confabulation is found sometimes but
  not always after px who survive aneurysms of the
  anterior communicating artery (ACoA)

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ACoA

• Ventral view of arteries in brain
• Damage to ACoA may result in memory loss,
  personality change and amnesia
• Damage to ACoA often results in PFC damage

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Executive functions

• Spontaneous confabulations
• Gilboa et al. (2006) investigated spontaneous
  confabulations
• Participants were ACoA individuals who
  confabulate, ACoA individuals who do not
  confabulate, and controls

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Executive functions

• Spontaneous confabulations
• Temporal context judgment experiment
• In this experiment participants were required to
  make temporal context judgments about pictures of
  objects (Was this object presented earlier in
  this list i.e., not a previous list?)
• Results
• Not all ACoA patients were impaired on the
  temporal context confusion experiment, but those
  with ventromedial prefrontal cortex damage were
  impaired

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Executive functions

• Spontaneous confabulations
• Familiar narratives experiment (fairy tales and
  bible stories)
• In this experiment participants were asked to
  recall familiar narratives
• Results spontaneous confabulators did not differ
  from ACoAs in terms of details recalled, but
  differed in terms of the number and type of
  errors (e.g., incorporation of details from other
  stories, idiosyncratic details)

91
Semantic narrative performance

• Top mean details produced
• Bottom proportion errors T total errors D
  distortions E external details (other
  stories) I idiosyncratic errors

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Executive functions

• Spontaneous confabulations
• Further analyses
• Only px with ventromedial prefrontal and
  orbitofrontal cortical damage were spontaneous
  confabulators

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Executive functions

• Spontaneous confabulations
• Conclusion spontaneous confabulation does not
  appear to be a result of confusing true memories
  in time (evidence spontaneous confabulator
  errors such as semantic narrative external
  details)
• instead it appears to be a difficulty of
  strategic retrieval and difficulties of
  monitoring
• Strategic retrieval refers to a type of memory
  retrieval in which the target memory is not
  directly elicited by the retrieval cue (e.g.,
  what did you do on your birthday?), but appears
  to require problem solving

94
Executive functions

• Spontaneous confabulations
• Evidence for strategic retrieval
• 1. Evidence from current study
• 2. Finding that spontaneous confabulation is
  observed even for remote memories acquired prior
  to brain damage (when encoding of memories was
  intact) suggests stored memory is relatively
  intact and problem is in retrieval

95
Executive functions

• Spontaneous confabulations
• Gilboa et al. proposed
• Strategic retrieval helps frame the memory
  problem and memory search
• Constrains memory search
• Once a memory is retrieved strategic retrieval
  monitors recovered memory for plausibility

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Executive functions
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Executive functions (social, personality and
emotional functions)

• Overview
• Gage walked away from accident, could describe
  the accident the next day, and within a month was
  deemed able to resume work as a foreman
• It became clear that Gage was no longer Gage
• Prior to injury Gage was a sober, responsible,
  intelligent, home body, with no peculiar or bad
  habits he was a responsible, valued employee
• After injury he was erratic, given to grossest
  profanity, impatient, unwilling to listen to
  advice, and unable to plan effectively
• Subsequent research has shown that damage to
  frontal lobes can lead to dramatic changes in
  personality while keeping perception,
  consciousness, and most cognitive functions
  intact