Executive Executive FunctionFunction

Ref: Banich pp.366-376 (skim “Cognitive estimation”), pp. 380-382 Ref: Banich pp.366-376 (skim “Cognitive estimation”), pp. 380-382

Behaviour Involves "Control"Behaviour Involves "Control"

• Taking initiativeTaking initiative

• Focusing a single task, ignoring distractionsFocusing a single task, ignoring distractions

• ““Multi-tasking” (switching between tasks)Multi-tasking” (switching between tasks)

• Planning, organising behaviour towards goalsPlanning, organising behaviour towards goals

• Thinking and acting flexiblyThinking and acting flexibly

• Reasoning, drawing inferencesReasoning, drawing inferences

These skills often referred to as “executive functions”These skills often referred to as “executive functions”

Prefrontal Cortex (PFC)Prefrontal Cortex (PFC)• = frontal lobes = frontal lobes excludingexcluding primary and secondary motor areas: primary and secondary motor areas:

• Rich interconnections with other cortical/subcortical regionsRich interconnections with other cortical/subcortical regions

Primary Motor Primary Motor

CortexCortexSecondary Motor Secondary Motor

CortexCortex

Prefrontal CortexPrefrontal Cortex

Three Major SubdivisionsThree Major SubdivisionsDorsolateral Dorsolateral

Prefrontal CortexPrefrontal Cortex

Orbitomedial Orbitomedial

Prefrontal CortexPrefrontal Cortex

Anterior CingulateAnterior Cingulate

Three Major SubdivisionsThree Major Subdivisions

1.1. DorsolateralDorsolateral - key role in executive functions (today) - key role in executive functions (today)

2.2. Anterior cingulateAnterior cingulate - evaluating one’s behaviour (Weds.) - evaluating one’s behaviour (Weds.)

3.3. OrbitomedialOrbitomedial - emotional aspects of control (Thurs.) - emotional aspects of control (Thurs.)

Some functions discussed earlierSome functions discussed earlier::

• Working memoryWorking memory

• Memory for temporal orderMemory for temporal order

• Source memorySource memory

Dorsolateral Prefrontal CortexDorsolateral Prefrontal Cortex

• Different regions specialised for different types of informationDifferent regions specialised for different types of information

e.g. verbal span - region anterior to Broca's area in left e.g. verbal span - region anterior to Broca's area in left

hemispherehemisphere

Working MemoryWorking Memory

• Cells in dorsolateral PFC can sustain activity over short delaysCells in dorsolateral PFC can sustain activity over short delays

Working memory may underlie many “executive functions”:Working memory may underlie many “executive functions”:

• goal-oriented behaviour involves keeping the goal in mindgoal-oriented behaviour involves keeping the goal in mind

• reasoning involves manipulating information “on line”reasoning involves manipulating information “on line”

Other PFC FunctionsOther PFC Functions

However, other PFC functions may go beyond working memory:However, other PFC functions may go beyond working memory:

1.1. Initiating new plans, activities (and knowing when to stop!)Initiating new plans, activities (and knowing when to stop!)

2.2. Attending to one activity, filtering out others (“dynamic filtering”)Attending to one activity, filtering out others (“dynamic filtering”)

3.3. Task switchingTask switching

4.4. Flexibility - suppressing habitual responses when inappropriateFlexibility - suppressing habitual responses when inappropriate

1. Initiation, Cessation of Action1. Initiation, Cessation of Action• P's with damage to dorsolateral PFC may exhibit P's with damage to dorsolateral PFC may exhibit Psychological Psychological

inertiainertia::

Dr. P was a successful surgeon, who while undergoing a simple operation, Dr. P was a successful surgeon, who while undergoing a simple operation,

suffered a brief hypoxia. After the surgery, standard IQ tests revealed Dr. P's suffered a brief hypoxia. After the surgery, standard IQ tests revealed Dr. P's

intelligence to be, for the most part, in the superior range. Yet, he could not intelligence to be, for the most part, in the superior range. Yet, he could not

handle many simple day-to-day activities... For example, his sister-in-law had to handle many simple day-to-day activities... For example, his sister-in-law had to

tell him to change his clothes... He did not initiate any activities or ask questions tell him to change his clothes... He did not initiate any activities or ask questions

about his existence, being content to spend his free time watching television.about his existence, being content to spend his free time watching television.

A waitress explaining why she had lost her job after frontal lobe surgery said, A waitress explaining why she had lost her job after frontal lobe surgery said,

"You have to have a "push" to wait on several tables at once, and I just didn't "You have to have a "push" to wait on several tables at once, and I just didn't

have it any more"have it any more"

1. Initiation, Cessation of Action1. Initiation, Cessation of Action

• Another common Another common feature of damage feature of damage to this region is to this region is PerseverationPerseveration::

Other PFC FunctionsOther PFC Functions

However, other PFC functions may go beyond working memory:However, other PFC functions may go beyond working memory:

1.1. Initiating new plans, activities (and knowing when to stop!)Initiating new plans, activities (and knowing when to stop!)

2.2. Attending to one activity, filtering out others (“dynamic filtering”)Attending to one activity, filtering out others (“dynamic filtering”)

3.3. Task switchingTask switching

4.4. Flexibility - suppressing habitual responses when inappropriateFlexibility - suppressing habitual responses when inappropriate

2. Dynamic Filtering

e.g. Stroop task:e.g. Stroop task:

• Give the name of the colour this word is written in:Give the name of the colour this word is written in:

Red

• Failed by P’s with dorsolateral PF lesionsFailed by P’s with dorsolateral PF lesions

2. Dynamic FilteringWisconsin Card Sorting Task:Wisconsin Card Sorting Task:

Cards can be sorted on three dimensions:Cards can be sorted on three dimensions:i. colouri. colour ii. shapeii. shape ii. numberii. number

P must sort on one dimension, ignore othersP must sort on one dimension, ignore others

Other PFC FunctionsOther PFC Functions

However, other PFC functions may go beyond working memory:However, other PFC functions may go beyond working memory:

1.1. Initiating new plans, activities (and knowing when to stop!)Initiating new plans, activities (and knowing when to stop!)

2.2. Attending to one activity, filtering out others (“dynamic filtering”)Attending to one activity, filtering out others (“dynamic filtering”)

3.3. Task switchingTask switching

4.4. Flexibility - suppressing habitual responses when inappropriateFlexibility - suppressing habitual responses when inappropriate

3. Task SwitchingTrail-Making Test:Trail-Making Test:

Must switch between two types of sequencingMust switch between two types of sequencing

Begin

End

4

C

1

B

2

3

A

D

3. Task Switching

Wisconsin Card Sorting Task:Wisconsin Card Sorting Task:

Following initial sort, P must Following initial sort, P must changechange his/her sorting rule his/her sorting rule

Other PFC FunctionsOther PFC Functions

However, other PFC functions may go beyond working memory:However, other PFC functions may go beyond working memory:

1.1. Initiating new plans, activities (and knowing when to stop!)Initiating new plans, activities (and knowing when to stop!)

2.2. Attending to one activity, filtering out others (“dynamic filtering”)Attending to one activity, filtering out others (“dynamic filtering”)

3.3. Task switchingTask switching

4.4. Flexibility - suppressing habitual responses when inappropriateFlexibility - suppressing habitual responses when inappropriate

• P’s with dorsolateral PFC damage may exhibit P’s with dorsolateral PFC damage may exhibit Environmental dependency Environmental dependency

syndromesyndrome::

a)a) Utilisation behaviourUtilisation behaviour

b)b) Imitative behaviourImitative behaviour

4. Flexibility/Inhibitory Control

Professor Lhermitte would place a hammer, nail and Professor Lhermitte would place a hammer, nail and picture on a table in the entryway to his office. On picture on a table in the entryway to his office. On seeing this array of objects, the frontal lobe patient seeing this array of objects, the frontal lobe patient might pick up the hammer and nail and hang the might pick up the hammer and nail and hang the picture on the wall.picture on the wall.

a)a) Utilisation behaviour:Utilisation behaviour:

4. Flexibility/Inhibitory Control

b)b) Imitative behaviour:Imitative behaviour:

Lhermitte sat opposite a patient and, without Lhermitte sat opposite a patient and, without

explanation, produced gestures. Some were explanation, produced gestures. Some were

innocuous: folding paper, combing his hair, or innocuous: folding paper, combing his hair, or

tapping his leg. Others were socially inappropriate: tapping his leg. Others were socially inappropriate:

thumbing his nose, chewing paper or kneeling in thumbing his nose, chewing paper or kneeling in

prayer. The patients with frontal lobe lesions prayer. The patients with frontal lobe lesions

mimicked these actions.mimicked these actions.

4. Flexibility/Inhibitory Control

P’s may also have problems with P’s may also have problems with CognitiveCognitive Flexibility Flexibility

Alternate uses test:Alternate uses test:

"Think of as many uses as you can for these objects" "Think of as many uses as you can for these objects"

e.g. brick, pencil, paper, clip, toothpicke.g. brick, pencil, paper, clip, toothpick

Verbal Fluency:Verbal Fluency:

““Say as many words as you can that start with ‘f’”Say as many words as you can that start with ‘f’”

Executive Control: Issues

• Many "Frontal" tasks can be described in >1 way:Many "Frontal" tasks can be described in >1 way:

e.g. Wisconsin Card Sorting Task: dynamic filtering, e.g. Wisconsin Card Sorting Task: dynamic filtering,

task switching or cognitive flexibility?task switching or cognitive flexibility?

• Problem of circularityProblem of circularity

• How can we describe what the frontal lobes do in a How can we describe what the frontal lobes do in a way that is way that is directly testabledirectly testable??

• Thursday - more on this issueThursday - more on this issue