the executive brain

Question 1

What are executive functions and why are they significant in cognitive processes?

Answer 1

Executive functions are high-level cognitive processes that manage and optimize basic cognitive processes, often likened to a “brain’s conductor.”

Question 2

How do executive functions differ from specific cognitive domains like memory or language?

Answer 2

Executive functions are domain-general, supervising cognitive processes like problem-solving and multitasking, unlike specific domains that focus on particular types of information.

Question 3

What are the 4 key executive functions in the brain?

Answer 3

Problem solving
Overcoming habitual responses
Task-switching
Multi-tasking

Question 4

What did disorders of executive functions used to be called? Why aren’t they called this now?

Answer 4

Used to be called ‘frontal lobe disorders’
We know know that executive functions are exclusively linked to the prefrontal cortex.

Question 5

What are the key regions of the PFC and what executive control function are they associated with?

Answer 5

Lateral surface - dorsolateral PFC + ventrolateral PFC - problem solving
Polar PFC - multi-tasking
Medial surface - ACC - overcoming habitual responses
Orbital surface - orbitofrontal/ventromedial PFC - task-switching

Question 6

What are the neural correlates of problem solving?

Answer 6

Increased left dorsolateral PFC activation when solving problems
Even higher in individuals with high trait deliberation (the tendency to think carefully before acting)

Question 7

Outline what has been found about problem solving through laboratory research.

Answer 7

38 ppt measured on trait deliberation - the tendency to think carefully before acting
fNIRS - used an adaptation of the Tower of London test, asked can you solve this in 2 moves?
Increased left dorsolateral PFC when solving problems - even higher for those with high trait deliberation

Question 8

What can damage to the PFC indicate about the role of executive functions?

Answer 8

Damage to the PFC often results in impaired executive functions, indicating the area’s critical role in these processes.

Question 9

Explain the concept of habitual response and how it relates to executive functions.

Answer 9

Habitual response – something we engage in automatically
This executive function is relayed to the concepts of:
 Response inhibition – reducing the likelihood of a particular thought/action
 Impulsivity – a behavioural tendency to make immediate responses or seek immediate rewards

Question 10

What are the tests used to measure overcoming habitual responses?

Answer 10

Stroop
GO/NO GO

Question 11

What does the Stroop test measure in terms of executive functions?

Answer 11

The Stroop test measures the ability to inhibit automatic responses (like reading a word) in favor of a less habitual task (naming the color of the ink).

Question 12

Outline the findings of STROOP and GO/NO GO tests in terms of the neural correlates of overcoming habitual responses:

Answer 12

Lesions in superior medial fontal lobes inc : Dorsomedial PFC, Anterior cingulate cortex (ACC) and Pre-supplementary motor area (pre-SMA) =

STROOP - slow reaction time and decreased correct responses
GO/NG - more false alarms (responding go when seeing a no go stim)

Concluded - Problem solving (what am I supposed to be doing?, dorsolateral PFC) and motor responses (doing the action, pre-SMA), and detecting errors (don’t make mistake again, ACC) are all involved in function of supressing habitual responses

Question 13

What has GO/NO GO studies found about the neural correlates of task inhibition?

Answer 13

 Lesions in superior medial fontal lobes associated with more false alarms (more responding go when seeing a no go stim):
* Dorsomedial PFC
* Anterior cingulate cortex (ACC)
* Pre-supplementary motor area (pre-SMA)
 Lesions in these areas = issues supressing habitual response

Question 14

What role does the anterior cingulate cortex (ACC) play in executive functioning, particularly in error detection?

Answer 14

The ACC is involved in error detection, showing increased activation during mistakes and aiding in error compensation.

Question 15

What evidence is there for the role of the ACC in inhibiting habitual responses, particularly in terms of error detection?

Answer 15

Usually when we make errors, we are slower and more accurate in subsequent trials. This is associated with ACC function of error detection and compensation. Evidence for this includes:
* ACC lesions in monkeys – don’t have this slower response in post trials
* EEG in humans – activation of ACC in response to errors
o Error-related negativity = a ERP detected when an error is made
o post-error, large negative deflection induced
o Appears to have its origins in ACC

Question 16

Outline the debate into the ACC’s role in error detection.

Answer 16

General agreement that ACC is part of an error prevention network - but how? Main theories:
- Strategic control processes to reduce response conflicts in a top-down manner and prevent the mistake in the future
- evaluative processes only detect response conflicts (diff neural correlated for control)
- or both

Question 17

What evidence is there to support that the ACC only plays a role in the evaluation of errors and overcoming habitual errors? What evidence is there to counter this?

Answer 17

Stroop test - manipulated response conflict (high vs low) and strategic control processes (low or high - manipulated expectancy of trial congruency)
ACC activity was not affected by trial type (congruent or incongruent) during trials where participants had high strategic control, regardless of response conflict levels.
ACC activity was highest during trials with high response conflict but low strategic control. These are situations where participants were not prepared for the conflict.
ACC prioritizes the evaluation of response conflict over direct involvement in strategic control processes - concerned with detecting and assessing conflicts in information processing rather than actively implementing strategies to resolve them.
Rushworth - argues that the dorsal (executive) and ventral (emotional) regions of the ACC work together to assess the value or responses, - is an action going to elicit a reward or punishment? Suggests habitual responses require monitoring responses to avoid those which elicit punishment/lower value

Question 18

How is task-switching tested, and what is the ‘Switch Cost’?

Answer 18

Task-switching is assessed with the Wisconsin Card Sorting Task, where reaction times measure the difficulty in shifting from one task schema to another.
Changes in reaction time when shifting between a a NO-SWITCH rule and SWITCH rule trial is known as a switch chost.

Question 19

When is the Switch Cost the largest in task-switching tasks? What evidence is there to support this?

Answer 19

Switch Cost if greater when discarding a complex schema to set up a simple one
Study found that bilinguals were slower at switching from their second language (L2, hard) to L1 (easy)

Question 20

Define task-switching (in terms of executive function).

Answer 20

Task switching – discarding a previous schema/structure of knowledge to establish a new one we are using (aka ‘set-shifting’)

Question 21

What is the difference between ‘hot’ and ‘cold’ executive control processes?

Answer 21

‘Hot’ processes involve reward-related stimuli, while ‘cold’ processes deal with cognitive stimuli independent of reward.

Question 22

How does the IOWA gambling task relate to the assessment of task-switching capabilities?

Answer 22

This task assesses the ability to switch from disadvantageous to advantageous decision-making strategies, impaired in individuals with ventromedial PFC lesions.

Question 23

Explain why individuals with ventromedial PFC lesions may perform well on STROOP inhibition tasks but perform poorly on the IOWA gambling tasks?

Answer 23

Due to the ‘hot’ (reward) and ‘cold’ (cog stim) executive control distinction.
Task switching (STOOP, WCST) - is a cold process
Impaired by lateral prefrontal cortex - connections with posterior sensory/motor regions
Reversal learning (IOWAGT, learning that a previously rewarded stim is no longer rewarded) - is a hot process
Impaired by damage to the orbitalfrontal region - connections to posterior affective areas

Question 24

Discuss the neural basis of multitasking and its associated regions in the brain.

Answer 24

Multitasking involves simultaneous maintenance of multiple goals, associated with right polar prefrontal regions and deficits in prospective memory.
(ex - Cold = lateral frontal cortex (connections with posterior sensory/motor areas)

Question 25

What evidence is there for the neural dissociation between the neural correlates of hot and cold processes?

Answer 25

monkeys with a ventro/orbital frontal lesion - intact task switching (cold) but impaired reversal learning (hot)
monkeys with a lateral prefrontal lesion - impaired task switching (cold) but intact reversal learning (hot)

IOWA gambling - ventromed/orbital fontal lesions - perform fine of STROOP (cold) but fail to switch from bad to good decks (reversal learning, hot)

Question 26

What does the study by Koechlin & Summerfield (2007) suggest about the hierarchical organization of the executive system in the brain?

Answer 26

The study posits a posterior to anterior gradient in the PFC, where increasing the complexity of the tasks requires greater involvement of anterior areas of the PFC
Polar PFC
o Maintaining current episodic control and a pending context (other task goals –complex multi-tasking
Anterior lateral PFC
o Using episodic control to switch to a different context (rule set)
Posterior lateral PFC
o Learned contextual information (rule set) guides response
Premotor cortex
o Simple stimulus-response mappings

Question 27

How are complex multitasking processes managed according to the gradient from posterior to anterior PFC?

Answer 27

Complex multitasking involves maintaining current control and pending contexts, primarily managed by the anterior lateral and polar PFC.

Question 28

What are the implications of damage to the right polar prefrontal region on multitasking abilities?

Answer 28

Lesions in this region result in deficits in managing time-based tasks and the strategic retrieval of intentions.

Question 29

Differentiate between the roles of the lateral PFC, polar PFC, medial PFC and orbital PFC in terms of executive functions

Answer 29

Lateral PFC:
o Problem-solving
o Task-switching
o ‘Cold’ cognitive control processes
Polar PFC:
o Multi-tasking
Medial PFC (including the ACC)
o assessing response conflict?
Orbital PFC:
o Task-switching –reversal learning
o ‘Hot’ cognitive control processes