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Cog neuro (y2s2) > Week 10 Lecture 10 - the executive brain > Flashcards

Week 10 Lecture 10 - the executive brain Flashcards

1
Q

What is executive function?

A
  • Control processes that enable an individual to optimise performance, requiring coordination of basic cognitive
    processes
  • Presumed necessary for ‘controlled’ behaviour in contrast to ‘automatic’ behaviour
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2
Q

Is executive function tied to a specific cognitive domain?

A

no

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3
Q

What can disorders of executive function result in?

A

difficulty with:

e.g.,

  • decision making
  • multi-tasking
  • paying attention
  • regulating emotions
  • ….. etc.
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4
Q

What post-injury changes occurred to Phineas Gage?

A
  • Impulsive decision making
  • Impaired planning
  • Poor regulation of social behaviour
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5
Q

What did a modern reconstruction of the damage to Phineas Gage’s skull reveal?

A

Damage in the left orbitofrontal/ ventromedial region and the left anterior region

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6
Q

What did disorders of executive function used to be called? What is executive function linked to now?

A
  • Disorders of executive function used to be called ‘frontal lobe disorders’
  • Now executive function is linked to the prefrontal cortex (PFC)
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7
Q

What are the 3 cortical surfaces in the PFC?

A
  • lateral
  • medial
  • orbital
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8
Q

What are the functional specialisations in the PFC?

A
  • refer to summary sheet for answers
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9
Q

How can executive function be measured in the lab?

A
  1. Task-setting and problem solving
  2. Overcoming potent or habitual responses
  3. Task switching
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10
Q

What are problem solving tasks (EF)?

A

Related to generalised measures of intelligence

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11
Q

What are task setting tasks (EF)?

A

Being presented with a goal and a starting point, then coming up with a solution

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12
Q

Give 2 example of task-setting and problem solving tests?

A
  • Tower of London
  • “FAS” test
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13
Q

What is the Tower of London task?

A

Beads should be moved from an initial position to a specified end-point according to the rules

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14
Q

What does the Tower of London task measure?

A
  • time to complete task
  • number of moves taken
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15
Q

A study by Shallice (1982) conducted a study using the Tower of London task.

What was the method?

A
  • 20 healthy controls
  • 61 patients with unilateral PFC lesions

CT scans used to group based on lesion
location:
- Anterior (L/R)
- Posterior (L/R)

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16
Q

A study by Shallice (1982) conducted a study using the Tower of London task.

What was found?

A

Damage to PFC results in poor performance, especially ‘left anterior’ PFC

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17
Q

Cognitive estimates is another example of tests of problem solving.

Give some examples of the questions that are asked in this test

A
  • “How many camels are in Holland?”
  • “How many brushings can someone get from a tube of toothpaste?”
  • “How high off a trampoline could a person jump?”
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18
Q

What is the FAS test?

A
  • ‘Produce as many words as you can starting with the letter F (or A or S)’
  • In 1 minute
  • No names
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19
Q

A study by Stuss et al., (1998) used the FAS test (a.k.a. letter fluency).

What was the method?

A
  • 37 healthy controls (CTL)
  • 74 patients with focal lesions in frontal and non-frontal areas
  • FAS letter fluency task
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20
Q

A study by Stuss et al., (1998) used the FAS test (a.k.a. letter fluency).

What was found?

A
  • Damage to the ‘left frontal dorsolateral
    cortex’ (LDL) particularly decreases
    performance
  • Fewer words in total vs. CTL (control group)
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21
Q

What is a habitual response?

A
  • A habitual response is one that we engage in automatically
  • This aspect of executive function is related to the concept of inhibition
  • Reducing the likelihood of a particular thought or action
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22
Q

Give 2 examples of tests that measure overcoming habitual responses (EF)?

A
  • Stroop test
  • go/no go test
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23
Q

What is the suggested explanation for the difficulty of the Stroop test?

A
  • Reading the word is automatic, so generates an incorrect response
    which must be inhibited
  • Incorrect response competes with the less-automatic task of naming the ink colour
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24
Q

A study by Alexander et al., (2007) used the Stroop test to investigate neural correlates with EF.

What was the method?

A
  • 38 healthy controls
  • 42 patients with frontal lesions
  • Stroop task (modified)

fMRI to relate lesion location to:
* Reaction times
* False positive – responding to Distractors/ Other with Button 1
* False negative – responding to Targets with Button 2

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25
Q

A study by Alexander et al., (2007) used the Stroop test to investigate neural correlates with EF.

What was found?

A
  • Lesions in left ventrolateral PFC = more false positives to Distractors
  • Lesions in a right superior medial region (anterior cingulate, pre-supplementary motor area, and dorsolateral areas) = slow reaction time and decreased correct responses
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26
Q

What is the go/ no go test?

A
  • Make a response (‘Go’) for certain stimuli but inhibit (‘No-go’) for other stimuli
  • In the experiment, more trials with ‘Go’
    stimuli ‘No-go’
  • Start to respond habitually to stimuli
    with ‘Go’ response
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27
Q

Picton et al., (2007) used the go/ no go test to study EF.

What was the method?

A
  • 38 healthy controls
  • 43 patients with focal frontal lesions
  • Grouped using MRI or CT scans

Go/No-go paradigm:
* Letters A, B, C, D all with equal probability

  • Stage 1 – “improbable go”:
  • Go: A
  • No-go: B, C, D
  • Stage 2 – “improbable no-go”:
  • Go: B, C, D
  • No-go: A subjects must inhibit “an infrequent, prepotent response”
    [habitual – typical no-go condition]
  • Reaction times
    Errors -
  • Misses
  • False alarms – related to impulsivity
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28
Q

Picton et al., (2007) used the go/ no go test to study EF.

What was found in terms of reaction times?

A
  • All subjects slower after making a false
    alarm in Stage 2
  • SM group: lesions in superior medial frontal lobe were slowest of all

Variability of reaction times:
* More variable in group with lesions in
ventrolateral PFC, possibly reflecting
impaired monitoring of performance

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29
Q

Picton et al., (2007) used the go/ no go test to study EF.

What was found in terms of errors: false alarms?

A

SM group: lesions in superior medial frontal lobe associated with more false alarms
* Dorsomedial PFC
* Anterior cingulate cortex (ACC)
* Pre-supplementary motor area (pre-SMA)

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30
Q

What is an evaluative point for task-setting and problem solving tasks (EF)?

A

Accuracy of lesion identification with CT scans?

31
Q

What are 2 evaluative points for tests concerning overcoming habitual response (EF)?

A
  • Not all models of executive function rely on the concept of ‘inhibition’ but instead consider biasing activation signals
  • Maybe a bias towards the ‘correct answer’ (ink colour) is needed, rather than an inhibition of the ‘incorrect answer’ (colour name)
32
Q

What is task switching? (EF)

A

Related to the concept of perseveration: failure to shift away from a previous response

33
Q

Give an example of task switching?

A

Wisconsin Card sorting test

34
Q

What is the Wisconsin Card Sorting Test?

A

Match a card to 1 of 4 reference cards

Symbols on cards vary in:
* Shape
* Number
* Colour
* But subjects not specifically told this!

35
Q

What do reaction times in the Wisconsin Card Sorting Test tell us?

A
  • A: minimal change in RT between No-switch and No-switch trials
  • B: Big difference in reaction times between No-switch and Switch trials
  • The Switch Cost
36
Q

What is the switch cost?

A

a slowing of response time due to
discarding a previous schema and setting up a new one

37
Q

Meuter & Allport (1999) conducted a study investigating the switch cost.

What was the method?

A
  • 16 Bilinguals
  • Numeral naming from text

Measured difference in reaction times when switching:
* 1st (dominant) to 2nd (weaker) language
* 2nd to 1st language

38
Q

Meuter & Allport (1999) conducted a study investigating the switch cost.

What was found?

A
  • Bilinguals are slower at switching from 2nd language (hard task) to 1st language (easy task)
  • The Switch Cost is greater because inhibiting the more complex schema has a cost
39
Q

Shallice et al., (2008) looked at the neural correlates for task-switching.

Who were the participants, what lesions were involved?

A

*38 healthy controls
41 patients with focal PFC lesions:
* Left lateral (LL)
* Right lateral (RL)
* Inferior medial (IM)
* Superior medial (SM)

40
Q

Shallice et al., (2008) looked at the neural correlates for task-switching.

What was being measured?

A

Task switching effects on RT and errors:
* Trial type (Switch/Repeat)
* Congruent/Incongruent button press
* Delay of cue (e.g., “Left or Right?”) on the screen long before or not long before
trial

41
Q

Shallice et al., (2008) looked at the neural correlates for task-switching.

What was found?

A
  • Reaction times slowest for SM group
  • Greater Switch Cost than controls
  • Error rates highest IM group

Linked to lesions in:
* Ventral orbitofrontal cortex
* Medial and orbitofrontal PFC

42
Q

What is the Supervisory Attentional
System?

A

A model consisting of a set of tasks and behaviours (schemas) and a biasing mechanism to activate/inhibit these according to current goals

43
Q

What does the supervisory attentional system look like?

A

look at summary sheet for answers

44
Q

Evaluation: tests of executive function:

What is evidence from lesion studies highly dependent on?

A
  • The nature of the task (and any modifications)
  • How patients with lesions are grouped
45
Q

Evaluation: tests of executive function:

Real-world evidence?

A
  • Sometimes, individuals with damage to PFC can pass standard laboratory tests despite exhibiting impairments in real-world behaviour
  • How much is the Wisconsin Card Sorting Test really like task-switching in the real world?
46
Q

Evaluation: tests of executive function:

How are the tests developed?

A

Tests developed coincidentally as we learned more about neural correlates of executive function?

47
Q

Give 3 examples of contrasting areas involved in EF.

A
  1. Orbital/ventromedial vs. lateral PFC
  2. Posterior vs. anterior lateral PFC
  3. Anterior cingulate cortex (ACC) vs. lateral PFC
48
Q

What are Hot vs. Cold control processes?

A

Control processes differ based on the nature of the stimuli being processed

  • ‘Hot’ stimuli – affective or reward-related
  • E.g. food (non-human animals) or money (humans)
  • ‘Cold’ stimuli – purely cognitive
  • E.g. sensory dimensions such as shape, colour
49
Q

What are the different neural correlates in the PFC for Hot vs. Cold control processes?

A
  • ‘Hot’ stimuli – orbitofrontal cortex
  • Which has connections with posterior affective areas
  • ‘Cold’ stimuli – lateral frontal cortex
  • Which has connections with posterior sensory/motor areas
50
Q

In terms of Orbitofrontal/ventromedial PFC vs. lateral PFC:

What is reversal learning?

A
  • Learning that a previously rewarded stimulus or response is no longer rewarded
  • ‘Hot’ control process
51
Q

In terms of Orbitofrontal/ventromedial PFC vs. lateral PFC:

What is set shifting (a.k.a task-switching)?

A
  • Discarding a previous schema and establishing a new one
  • ‘Cold’ control process
52
Q

In terms of Orbitofrontal/ventromedial PFC vs. lateral PFC:

Dias et al. (1996) conducted a study on marmoset monkeys.

What was the procedure?

A
  • Compound stimuli made of lines and
    shapes
  • Training to respond to certain items in a
    dimension (e.g., a circle Shape) through
    reward until learned, regardless of the
    other dimension (any Lines)

Lesions in either:
* Orbitofrontal cortex
* Lateral frontal cortex

Post-lesion training:
* Reversal: same Shapes and Lines, but
rewarded for different Shape (unlearn
old rule)
* Dimension shift: new Shapes, rewarded
for a certain Line (learn a new rule)

53
Q

In terms of Orbitofrontal/ventromedial PFC vs. lateral PFC:

Dias et al. (1996) conducted a study on marmoset monkeys.

What was found?

A
  • a double dissociation (see summary sheet)
  • Suggests dissociable neural correlates for control of reward-related (‘Hot’) vs. purely cognitive (‘Cold’) stimuli
54
Q

For individuals with PFC lesion, what could a distinction between brain areas responsible for ‘Hot’ and ‘Cold’ control processes explain? What did this lead to?

A

could explain individuals with PFC lesions who are:
* Impaired in the real-word (e.g., impaired regulation of social behaviour)
* ‘Hot’ – salient rewards for appropriate social interactions (e.g., in-group benefits)
* Spared in laboratory tests of executive function
* ‘Cold’ – cognitive dimensions such as shape/colour without salient rewards
* (unless money…?)

lead to development of the somatic marker hypothesis

55
Q

What is the Somatic Marker Hypothesis (Damasio, 1996)?

A

Proposes that emotional and bodily states
associated with previous behaviours are used to influence decision making

  • Emotional events (e.g., a risky situation) store ‘somatic markers’ in memory
  • Somatic markers are believed to be stored in orbitofrontal/ventromedial PFC
  • Somatic markers may be unconscious or conscious
  • Retrieving that event reinstates the somatic marker (if PFC undamaged…)
  • This guides behaviour (e.g., making a response more or less likely)
56
Q

What evidence is there for the Somatic Marker Hypothesis?

A

Iowa Gambling task

57
Q

What is the Iowa Gambling task?

A

Iowa Gambling task
* Subjects given a “loan” of $2000
* Each round, choose a card from 1 of 4 decks
* Receive either a gain or a penalty

Decks have different returns over the entire test:
* A+B = ‘Bad’ decks
* C+D = ‘Good’ decks

58
Q

What are the results from the Iowa Gambling task for healthy controls?

A
  • Learn to switch from ‘Bad’ decks (A+B) to ‘Good’ decks (C+D)
  • Show anticipatory skin conductance response when selecting from ‘risky’ (‘Bad’)
    decks during the game
59
Q

What are the results from the Iowa Gambling task for Patients with orbitofrontal PFC lesions?

A
  • Fail to switch from ‘Bad’ decks to ‘Good’ decks
  • Do not show anticipatory skin conductance response when selecting from ‘risky’ decks
  • Show intact performance on other tests of executive function (Stroop, WCST)
60
Q

Patients with orbitofrontal PFC lesions fail to switch from ‘Bad’ decks to ‘Good’ decks in the Iowa Gambling task.

Explain how this could be a failure of reversal learning

A
  • Early in the game: Decks A+B are rewarded
  • Because Decks C+D have smaller gains
  • Late in the game: Decks C+D
    are rewarded
  • When early-game gains are equivalent for ‘Bad’ and ‘Good’ decks, patients with
    ventromedial PFC perform as controls (Maia & McClelland, 2004)
61
Q

What does the posterior PFC include?

A

premotor cortex, and regions such as
Broca’s area

62
Q

Is the anterior PFC understood?

A

less well-understood until recently

63
Q

What is the anterior PFC though to be involved in?

A

Multi-tasking:

  • Carrying out several tasks in succession
  • Requiring both task-switching and maintaining future goals in mind,
    while dealing with current goals
  • These tasks in isolation do not recruit anterior PFC
  • Combined, the PFC is implicated
64
Q

Koechlin & Summerfield (2007) proposed a hierarchically ordered executive system.

What did this look like?

A

anterior→posterior gradient for simple→complex tasks

65
Q

Koechlin & Summerfield (2007) proposed a hierarchically ordered executive system.

Explain the hierarchy in detail

A

Sensory control:
* Premotor cortex
* Simple stimulus-response mappings

  • Contextual control:
  • Posterior lateral PFC
  • Learned contextual information (rule set)
    guides response
  • Branching control:
  • Anterior lateral PFC
  • Using episodic control to switch to a different context (rule set)
  • Branching control:
  • Polar lateral PFC
  • Maintaining current episodic control and a pending context (other task goals - complex multi-tasking)

(also see summary sheet)

66
Q

What are the subdivisions of the Anterior Cingulate cortex (ACC)?

A
  • Dorsal region implicated in executive functions
  • Ventral region implicated in emotional
    processing
67
Q

Humans and non-human primates are slower and more accurate after making an error

What evidence is there to suggest that this process recruits the ACC?

A
  • ACC lesions in monkeys → Error +1 is not slower or more accurate
  • EEG evidence of a response in the ACC to errors
68
Q

What is error related negativity?

A

an event-related potential component in EEG detected when an error is made

69
Q

Where does error related negativity appear to have its origin?

A

in the ACC

70
Q

van Veen & Carter (2002) investigated the role of the ACC in terms on response conflict.

What was the method?

A

Stroop with modification about response conflict expectancy

Trial types:
* Congruence expected – low involvement of strategic processes
* C/c = congruent trials
* C/i = incongruent trials

  • Incongruence expected – high involvement of strategic processes
  • I/c = congruent trials
  • I/i = incongruent trials
71
Q

van Veen & Carter (2002) investigated the role of the ACC in terms on response conflict.

What was the result?

A

ACC activation when trials are unexpectedly incongruent, i.e.,
involving most response conflict

72
Q

What can Orbital/ventromedial vs. lateral PFC also be known as?

A

emotional vs. cognitive control

73
Q

What can Posterior vs. anterior lateral PFC also be known as?

A

simple vs. complex/multiple tasks

74
Q

What can ACC vs. lateral PFC also ben known as?

A

error detection vs. control of responses

Cog neuro (y2s2) (11 decks)

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