Executive functions and memory

Question 1

What are executive functions and what brain region are they supported by?

Answer 1

Cognitive control processes mainly supported by prefrontal cortex. They regulate lower level processes such as perception, motor control and memory search.

Question 2

Give some examples of executive functions

Answer 2

• self regulation
• Self-directed behaviour towards a goal
• Break out of habits (e.g not shaking hands during corona)
• Make decisions (frontal legions)
• Evaluate risks
• Plan for the future
• Prioritise and sequence actions

Question 3

Name and describe the Miyake model of executive functions

Answer 3

The unity/diversity model

It focuses on three aspects of the executive function:

• Updating (working memory)
• Shifting
• Inhibition
• A common executive function (EF) which spans these components

Question 4

What is meant by shifting?

Answer 4

Shifting between task sets or response rules (reading a paper to email).

Question 5

What is meant by the shifting cost

Answer 5

It takes quite a cognitive load to shift between these tasks because you have to completely shift the contents to your working memory

Question 6

Name two good measures of shifting

Answer 6

Wisconsin card sorting task

Trail making task B (switch between putting digits and letters in order)

Question 7

What is meant by inhibition?

Answer 7

Suppressing or resisting a prepotent(automatic) response in order to make a less automatic but task-relevant response (checking Facebook)

Question 8

Name two tasks which measure inhibition

Answer 8

Stroop task

Go/No Go task

Question 9

What is meant by updating?

Answer 9

Monitoring and coding incoming information for task relevance, and replacing no longer relevant information with newer, more relevant information

Question 10

What task is useful for measuring updating?

Answer 10

Spatial n-back task
–First look for A, B, or C
–Then, for B, C, or D (dropped A, added D)
–Then, for C, D, or E

Question 11

What is important to note about these designated tasks?

Answer 11

They often measure multiple executive functions and cognitive processes at once

Question 12

How could ‘purer’ neuropsychological tasks help? (2)

Answer 12

Theory development and

allow better diagnosis

Question 13

In the paper, they do a re-analysis and refactoring of the original Miyake model. How did they do this?

Answer 13

They had a large sample of 17-year old twins that did a wide range of tasks and then they did a factor analysis on that to see which tasks correlated highly with other tasks.

Question 14

What did the study conclude about this model? (3)

Answer 14

The inhibition aspect correlated very highly with the common (EF) factor. Individual differences in common EF fully account for individual differences in inhibition.

Psychopathology may be more broadly associated with impairment in common EF (like common intelligence)

No very high correlation between common EF and IQ: These are different concepts

Question 15

How did they refactor the model?

Answer 15

Look at diagram

Basically inhibition is replaced by common EF which is correlated with all the tasks

Question 16

Why is it very difficult to measure the aspects of executive functions?

Answer 16

Non-EF processes and error contribute much variance
A specific EF factor is typically accompanied by a common EF factor (which you don’t want to measure)

Score on an EF task = specific ER factor < Common EF factor < Non-EF Processes < error

Question 17

What are the dangers of inadequate measurements?

Answer 17

More subtle effects of EF may be missed due to ceiling effects and error which leads to false negatives (is there really no problem with updating in Alzheimers or did we just miss it?)

Question 18

Why is there a link between EF and Addiction and depression?

Answer 18

-Reduced executive functioning
=> Reduced cognitive control
=> Less able to maintain long-term goals: Cannot resist temptations or control negative thoughts

Question 19

What was the need for a central executive?

Answer 19

There was a need for memory control processes when task demands are high. It served as a place holder for not yet well understood functions

Continuing research was going to make the role of the ‘homunculus’ smaller as we gain more understanding of the processes involved

Question 20

Describe the dual-task performance study by Baddely et al (1986)

Answer 20

They calibrated healthy ageing subjects on two tasks for maximum single-task performance:

• Remembering random digits (phonological)
• Tracking a moving target (visa-spatial)

Then they did both tasks together. It was found that there was only a 10-15% drop in performance. Therefore different systems.

Question 21

What happened when they repeated this dual-task study in people with early Alzheimers? What conclusions were drawn?

Answer 21

same performance same task but on dual task 40% drop in performance

Therefore Alzheimer’s patients had a specific problem with dual-tasks irrespective of the task difficulty (can also be seen in packing or cooking)

This appears to be a problem with

• task coordination
• temporary binding (later relegated to the episodic buffer)

Question 22

What has dual task impairment found to be related to?

Answer 22

Overlap of size of shared brain areas

Question 23

Describe a task which measures the central executive and the reasoning behind it.

Answer 23

Random generation:
Participants have to generate random digits, letters, places etc. This requires keeping switching retrieval strategies (e.g ordering ) of the letters and inhibit already used orderings.

This should inhibit retrieval from long term memory because the central executive is too busy to do this (like counting backwards in 7s disrupts rehearsal). Tests can be done to check for randomness.

It seems to strongly involve the central executive but it is difficult to use in practice.

Question 24

Describe a task which measures working memory which is a bit better than e.g digit span

Answer 24

Complex span: reading span
Subjects have to read sentences and comprehend them by answering pretty simple questions about them and also remember the last word of the sentence and previous sentences.

The number of sentences processed with all last words remembered = reading span

Question 25

What is this reading span highly correlated with? (3)

Answer 25

Language comprehension
exam performance
IQ (includes some span tasks)

Question 26

What task/ EF aspect does the span tasks have a low correlation with?

Answer 26

n-back tasks (Updating)

Question 27

How has this central executive homunculus been updated in the 90’s?

Answer 27

Now multiple cognitive processes, each of which serves a specific function in memory, therefore it is more likely that there are several networks or areas involved rather than one area. Performance is perhaps contained by the effectiveness of neural communication.

Homunculus is an emergent property of how different brain networks interact and are deployed to meet task requirements.

Question 28

What did Logie find that communication between different cognitive functions was crucial for?

Answer 28

Communication between different cognitive functions crucial for successful dual task performanceand for successful temporary feature binding

Question 29

What other form of executive process did they find?

Answer 29

Selection and implementation of retrieval strategies[howto retrieve things] appears to be another form of executive process