Executive processes

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Executive processes

• What are executive processes
• Executive processes coordinate mental activity so
  that a particular goal is achieved
• modulate operation of other processes (modulate
  to guide or modify) however, executive processes
  do not actually carry out these activities
• Executive processes also called cognitive control
  processes

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Executive processes

• Properties of executive processes
• Bias our selection of thoughts and actions
• coordinate mental activity so that a particular
  goal is achieved
• Override automatic thoughts and habitual actions
• Enables simulation of plans, identification of
  consequences

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Executive processes

• Neural basis
• Frontal executive hypothesis executive processes
  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

• Neuroanatomy of the 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 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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Executive functions
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Executive functions

• Frontal lobe
• Major subdivisions of prefrontal cortex lateral
  prefrontal cortex, ventromedial prefrontal
  cortex, and anterior cingulate
• Frontal pole most anterior end of frontal lobes

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Kolb Whishaw frontal lobe figure fyi

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

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Executive processesfyi

• 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

• 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 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
• Baddeleys model 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

• Test of Content vs process-based models of WM
• 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
• Aside 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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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 processes

• Conclusions
• DEsposito findings are inconclusive, but do
  provide support for the hypothesis that
  maintenance plus processing occurs in a different
  region (dorsolateral PFC) than maintenance
  processing
• This is consistent with process-based models of WM

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Executive functions

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

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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 executive dysfunction and
  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 function needed when 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)
• An incompatibility between an automatic response
  and a correct response results in Stroop-like
  effects

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Executive functions

• Stimulus-response compatibility
• Stimulus response compatibility exists when the
  response 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
• Stimulus response compatibility 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

• Cohens model of Stroop
• Cohen and colleagues have developed a neural
  network model of Stroop task
• model 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

• Cohens model of Stroop
• 1. attention controller
• This process keeps track of the task goal
• 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

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Executive functions

• Cohens model of Stroop
• 2. conflict monitor
• This process monitors the amount of conflict
  between potential responses

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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
• Consistent with Cohen model 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 memory for temporal order
• 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 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 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?
• 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

• Spontaneous confabulations
• Individuals, who spontaneously confabulate have
  also been used to investigate role of the frontal
  lobes and executive function in memory
• Spontaneous confabulation statements are
  actions that reflect unintentional but obvious
  distortions of memory
• honest lying
• Spontaneous 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)

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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

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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

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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
• Strategic retrieval appears to be mediated by the
  ventromedial and orbito-frontal regions of the
  PFC

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Executive functions

• Goal planning
• Many goals have goal/subgoal hierarchical
  structure
• E.g., goal Do well on exam
• Subgoals complete readings go to lectures
  study before exam be well rested
• Subgoals of study before exam
• Outline lectures/readings
• Make sure all notes are available
• Study with a friend
• Subgoal of outline readings
• Read 3 sections of chapter per day outline
  reading as I go review outline when done

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Executive functions

• Many goals have goal/subgoal hierarchical
  structure
• Notes
• 1. hierarchical structure
• 2. higher-level goals are more abstract than
  lower level goals

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Executive functions

• Goal planning
• To achieve these types of goals necessary to
• Identify goal/subgoal structure
• Identify resources needed to achieve each goal
  and subgoal
• Identify consequences of different subgoals

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Executive functions

• Goal planning
• Identify resources needed to achieve goal (e.g.)
• Set aside time to attend lectures
• Be sure to outline lectures/readings
• Consequences of means to achieve subgoals (e.g.)
• Review with friend friend wants to party, you
  have romantic interest in friend oops!!)
• Study by cramming inefficient study approach
  especially because final is cumulative, and I
  will be tired dont do it!

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Executive functions

• Goal planning implications
• If complex goals are hierarchical then
• Achieving a complex goal can fail for several
  reasons
• clinical and experimental literature findings
  have showed that failure occurs for several
  different reasons

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Executive functions

• Effects of abstraction on performance and brain
  activation Neuroimaging study
• Manipulated abstraction by constructing 4
  conditions that varied in abstraction
• simplest task (a)
• More abstract task (b)
• Quite abstract task (c)
• Most abstract task (d)
• Badre et al., 3007, J of Cognitive Neuroscience

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Executive functions

A premotor cortex was sensitive to all 4
tasks B anterior premotor cortex was sensitive
to all but the most simple task C inferior
frontal sulcus was sensitive to the 2 most
abstract tasks D frontopolar cortex was only
sensitive to the most abstract task
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Executive functions

• Results
• More complex/abstract tasks activated more
  anterior regions than less abstract tasks
• More anterior regions were more sensitive, that
  is, were only activated by more abstract tasks
• Conclusions
• 1. more abstract tasks rely regions that process
  less abstract information suggests that
  participants impaired in their performance of
  less abstract tasks will fail on more complex
  tasks conversely participants, who perform tasks
  at all but the highest level should be able to
  perform less abstract tasks

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Executive functions

• Conclusions contd
• 2. Findings are consistent with the idea that PFC
  function has a gradient from more specific to
  more abstract processing
• More specific processing in the more posterior
  motor areas, more abstract in the more anterior
  brain regions, and most abstract in the most
  anterior, polar regions of the frontal lobe

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Executive functions

• Lesion studies of hierarchical goal-subgoal
  planning
• Implication of hierarchical goal-subgoal planning
  is that px who fail on simpler tasks will also
  fail on more complex tasks
• Badre et al. (2009) investigated px with PFC
  damage using the same task just described
• px with more posterior damage centred on the
  pre-motor cortex failed on all tasks
• Px with more anterior damage were unimpaired on
  less abstract tasks (a and b), but impaired more
  abstract tasks (c and d)

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

• This slide is a diagram of the skull of Phineus
  Gage
• As a result of this patient we now know that
  executive functions are also involved in
  personality, social, and emotional functions