L20. Prefrontal Cortex

Question 1

The frontal lobe makes up 30% of brain volume and has a diverse range of functions. What are some of these? [3]

Answer 1

Executive Functioning

1. Motor Control
2. Language
3. Higher level congnition

Question 2

What is meant by the term executive function?

Answer 2

An umbrella term that describes inter-related processes responsible for goal directed, purposeful behaviour

Often includes social and emotional behaviour as well

Question 3

What are the 3 main parts of the pre-frontal cortex? Describe each one anatomically

Answer 3

1. Dorsolateral: top and side view of the cortex
2. Medial: where the two hemispheres come together
3. Orbital: Underneath the cortex (from below)

Question 4

What is the dorsolateral prefrontal cortex responsible for?

Answer 4

Traditional executive functions: thinking and high cognitive function

• Working memory
• Response selection
• Planning and organising
• Hypothesis generation
• Flexibility maintining or shifting set (between competing demands)
• Insight
• Moral judgment

Question 5

What vessel supplies the dorsolateral prefrontal cortex?

Answer 5

The middle cerebral artery (MCA)

Question 6

What is the medial prefrontal cortex responsible for?

Answer 6

Emotional and motivational interface (not mood)

• At most extreme may see akinetic mutism
• Movitivation: deficit will show apathy and indifference
• Initiative

Question 7

What vessel supplies the medial prefrontal cortex?

Answer 7

The anterior cerebral artery

Question 8

What is self-awareness?

Answer 8

Knowing your place in the world and the place of the world around you:

• Attribution of emotions in other people
• the areas involved in attribution in self is co-localised with others
• Damage to the areas of the prefrontal cortex (medial) that control these areas show egocentricism

Question 9

What is the orbitofrontal prefrontal cortex responsible for?

Answer 9

It is highly connected to the limbic areas

• Filtering system: emotion, cognition and social
• Impulsivity

Question 10

What vessel is the ortibo prefrontal cortex supplied by?

Answer 10

The anterior cerebral artery and the middle cerebral artery

Question 11

What do people with lesions in the orbital prefrontal cortex do in comparison with normal people?

Answer 11

They tend to rush and do things without thinking about them - forgo accuracy for timing

Question 12

Describe the development of executive functions

Answer 12

Executive functions are not present at birth, and have a specific pattern of development.

The frontal lobe is the last area of the brain to develop and is also one of the first/earliest to start degenerating.

• Lower order functions develop first
• Higher order (set shifting and reasoning) develop later

Damage to the brain during development causes severe impact on these abilities

Question 13

The development of frontal lobes is a dynamic process involving positive and negative processes. What is meant by this?

Answer 13

Development occurs until about the age of 20

• Positive process: a strengthening and proliferating “use-it-or-lose-it” process.
• Negative process: a pruning where areas lacking stimulation will not proliferate and will eventually ‘die off’

Question 14

Is frontal lobe dysfunction synonymous with executive dysfunction? Why or why not?

Answer 14

It is not

The frontal lobe is highly connected with other regions of the brain. A lesion anywhere in the complex network will compromise executive functioning.

Question 15

If the brain is an executive system, then what role does the pre-frontal cortex have to executive functioning?

Answer 15

It is the coordinator

Question 16

What is the difference between a positive symptom and a negative symptom of executive dysfunction? Give examples

Answer 16

Positive symptom: outward projections that have a profound impact on society and the healthcare system

• distractibility
• social disinhibition
• emotional instability
• preservation
• impulsivity

Negative symptoms: lack of functioning and profound impact on family

• lack of concern
• restricted emotion
• deficient empathy
• failure to complete tasks
• lack of initiation

Question 17

What are some common causes of executive dysfunction?

Answer 17

• Closed head injury
• stroke
• pyschiatric conditions (schitzophrenia, mania)
• dementia
• focal lesions
• inflammation (MS, Encephalitis)
• Developmental (autism)

Question 18

What are some tests for prefrontal cortex dysfunction? What are their aims?

Answer 18

1. Tower of london - planning and reasoning
2. Stroop Test - inhibition
3. Rey complex figure test - planning