Prefrontal Cortex and Executive Function

Where was Phineas Gage’s damage located in his brain?

Left lower forebrain and connections between left and right frontal cortices

What happened to Phineas Gage?

Personality completely changed and decline in cognitive functioning

Patients with Bilateral Prefrontal Cortex Damage have what 5 characteristics?

1. Highly distractible

2. Lack of foresight

3. Unusually stubborn

4. Lack of motivation

5. Loss of sense of what is socially acceptable

What is meant by highly distractible in patients with bilateral prefrontal cortex damage?

Turning from one activity to another according to novelty of new stimulus rather than a plan

What is meant by lack of foresight in patients with bilateral prefrontal cortex damage?

Not able to anticipate or predict future events

What is meant by unusually stubborn in patients with bilateral prefrontal cortex damage?

In the face of advice that they do not agree with, they may remain firm on an action

What are the three aspects of executive functioning?

1. Working memory

2. Inhibitory control

3. Cognitive flexibility

Short-term maintenance and manipulation of information

Working memory

Self Control: Controlling your attention, behavior, emotions to override a strong internal or external cue

Inhibitory Control

Adjusting to new demands, rules, or priorities

Cognitive Flexibility

Which part of executive functioning is N-back task associated with?

Working memory

N-Back Task

• Indicate whether each stimulus matches the one N-back (e.g. 2 trials before in the 2-back task)

What happens as N gets larger?

More errors

N-Back Task

• Indicate whether each stimulus matches the one N-back (e.g. 2 trials before in the 2-back task)

• More errors occur as N gets larger

  Usually when __-back there is no success

5

N-Back Task

• Indicate whether each stimulus matches the one N-back (e.g. 2 trials before in the 2-back task)

• More errors occur as N gets larger

• Usually when 5-back there is no success

• Shown slides of numbers and subjects think back to 2 back from the slide they are on to determine if the numbers match and if they do they report it is a match

  What two processes is this task working in working memory?

Stimulus maintenance and removal

Which aspect of executive functioning is the stroop test testing?

Inhibitory control

Stroop Test

• Name the font color when it is incongruent with the word

• resolving conflict from more dominant word reading response

What were the results?

Slower to name font color when incongruent with the color word

What is the Wisconsin test testing in executive functioning?

Cognitive Flexibility

Wisconsin Test

• Sort cards based on “set”: color, number, or shape

• Discover the rule based on the feedback from the researcher

  What happens after a bunch of correct sorts?

The rule changes

Wisconsin Test

• Sort cards based on “set”: color, number, or shape

• Discover the rule based on the feedback from the researcher

• The rule changes after a bunch of correct sorts

  How is inhibitory control being tested?

Need to inhibit shape to sort by color or vise versa

Wisconsin Test

• Sort cards based on “set”: color, number, or shape

• Discover the rule based on the feedback from the researcher

• The rule changes after a bunch of correct sorts

  How is interference being tested?

proactive interference of the first rule you learn causes you to struggle to complete the second rule

Wisconsin Test

• Sort cards based on “set”: color, number, or shape

• Discover the rule based on the feedback from the researcher

• The rule changes after a bunch of correct sorts

  How is working memory being tested?

Focused on a specific rule

Wisconsin Test

• Sort cards based on “set”: color, number, or shape

• Discover the rule based on the feedback from the researcher

• The rule changes after a bunch of correct sorts

  Not good at switching between rules would conclude…

Loss of flexibility or managing interference

______________ prefrontal cortex in rats: smaller, less interconnection, and less complicated

less developed

Monkeys prefrontal cortex is fairly _________ to humans, but not as divided up.

similar

________ engage in the highest cognitive functions in comparison to rats who engage in much simpler thinking.

Humans

What two things are sub-regions in the brain differentiated by?

1. Cell composition

2. Connectivity with other brain regions

Evidence from __________ suggests that sub-regions of the prefrontal cortex might have different functions.

lesion/damage

What is the Dorsolateral prefrontal Cortex responsible for?

N-back tasks and working memory

What is the Lateral prefrontal cortex responsible for?

Stroop Test or inhibitory control

What is the Ventrolateral Prefrontal Cortex responsible for?

Wisconsin Test or Cognitive Flexibility

Evidence from ____________ studies suggest activation of multiple prefrontal cortex regions across multiple types of executive function tasks

Neuroimaging

What does the evidence of activation of multiple prefrontal cortex regions across multiple types of executive function tasks support?

Multiple aspects of the prefrontal cortex being used for the Wisconsin Test

Why is it difficult to determine if different regions of the prefrontal cortex have different functions? 3 reasons

1. Tasks may involve more than one executive function

2. Anatomical borders are not clearly defined

3. Rat prefrontal cortex is not as complex as humans so there are limits to what we can learn

Patients with _____________ damage struggle with real-life decision-making and appear to be unable to learn from their mistakes.

orbitofrontal cortex

Patients with orbitofrontal cortex damage can be fine and perform normally on standard lab tests of ________ ___________, _________ ________, and _________ ___________

working memory, inhibitory control, and cognitive flexibility

______________ was the main area of damage in Phineas Gage

Orbitofrontal Cortex

The __________________ is a lab measure of decision-making

Iowa Gambling Task

What does the Iowa Gambling Task show?

Orbitofrontal damage is associated with an inability to act on future consequences of actions

Iowa Gambling Task

Participants presented with 4 decks of cards:

• Deck A: each card worth $100 but 50% of the time pay a $250 penalty

• Deck B: each card with $100 but 10% of the time pay a $1,250 penalty

• Deck C: each card worth $50 but 50% of the time pay a $50 penalty

• Deck D: each card is work $50 but 10% of the time pay a $250 penalty

What happened at first?

Deck A and B seem better because they are worth more money

Iowa Gambling Task

Participants presented with 4 decks of cards:

• Deck A: each card worth $100 but 50% of the time pay a $250 penalty

• Deck B: each card with $100 but 10% of the time pay a $1,250 penalty

• Deck C: each card worth $50 but 50% of the time pay a $50 penalty

• Deck D: each card is work $50 but 10% of the time pay a $250 penalty

• At first Deck A and B seem better because they are worth more money

Why is it actually smarter to choose Deck C and D?

They lead to overall gain

Participants presented with 4 decks of cards:

• Deck A: each card worth $100 but 50% of the time pay a $250 penalty

• Deck B: each card with $100 but 10% of the time pay a $1,250 penalty

• Deck C: each card worth $50 but 50% of the time pay a $50 penalty

• Deck D: each card is work $50 but 10% of the time pay a $250 penalty

• At first Deck A and B seem better because they are worth more money

• But, Decks C and D lead to overall gain, so they should actually be the choice

  How did participants with orbitofrontal damage perform?

Difficulty learning that Deck C and D lead to more money in the future