Prefrontal cortex and executive functioning Flashcards
How much of the brain volume is occupied by the frontal lobe?
30%
What are the principles of subdivision of the frontal lobe?
Subdivision based on:
cytoarchitecture
thalamic connections
functional properties
Which types of connections are generally used in the subdivision of the frontal lobe based on thalamic connections?
Afferent connections
Efferent connections
Are afferent or efferent connections usued more commonly to subdivide the frontal lobe based on thalamic connections?
Afferent connections
Broadly map onto Brodmann areas
Describe some examples of subdivision of the frontal lobe based on functional distinctions?
Motor area
Premotor area
Prefrontal area
Broca’s area
PICTURE FROM SLIDE 7
What was the Phineas Gage lesion study useful for?
Understanding frontal lobe functioning
Which part of Luria’s functional system corresponds to the frontal lobe?
Which functions is it responsible for?
Anterior unit
Planning, executing and verifying behaviour
What is executive functioning?
Which lobe of the brain is it associated with?
An umbrella term to describe the inter-related processes responsible for goal-directed, purposeful behaviour
Incudes emotional and social behaviour as well as cognition
Considered a frontal lobe function
What are the major subdivisions of the the pre-frontal cortex?
Dorsolateral pre-frontal cortex
Medial pre-frontal cortex
Orbitofrontal prefrontal cortex
What are the major functions of the dorsolateral PFC?
Traditional executive functions:
Working memory
Response selection
Plannig and organising
Hypothesis generation
Flexibility maintaining
Insight
Moral judgement
What is the major arterial supply to the dorsolateral PFC?
Middle cerebral artery
Decsribe the functions of the medial PFC?
Emotional-motivational interface:
Apathy
Initiative
Indifference
Akinetic mutism at most extreme
What is the major arterial supply to the medial PFC?
Anterior cerebral artery
Issues with self-awareness can arise from lesions in which part of the frontal lobe?
Medial PFC
Anterior cingulate
Which deep brain strucutres is the orbitofrontal PFC highly connected to?
Limbic areas
Describe the functions of the orbitofrontal PFC?
Inhibiton (emotional, social, cognitive)
Impulsivity
What is the major arterial supply to the orbitofrontal PFC?
Anterior cerebral and middle cerebral arteries
Problems with impulsivity are evident in individuals with lesions in which part of the frontal lobe?
Orbitofrontal PFC
Describe the maturation of the frontal lobes?
Last area of the brain to develop
First part of brain to degenerate in ageing
Development is a dynamic process, involving both positive and negative processes (eg. proliferation vs pruning)
What is the functional consequence of the frontal lobe being the last area of the brain to develop?
Executive functions are among the last abilities to reach maturity
Lower order functions develop first
Higher order functions develop later
What is executive dysfunction?
Problem with execuitve functioning
POSITIVE SYMPTOMS: distractibility, social disinhibition, emotional instability, etc.
NEGATIVE SYMPTOMS: lack of concern, restricted emotion, deficient empathy, etc.
Are executive dysfunction and frontal lobe dysfunction the same thing?
NO
Pathology of executive dysfunction is likely to be in the frontal lobe, but not necessarily
Prefrontal cortex is just a ‘coordinator’ of executive functioning
Which lesions are formal neuropsychological tests most sensitive to?
Whic types of lesions are more difficult to test?
DLPFC lesions
Medial and orbitofrontal are difficult to formally assess
How can DLPFC lesions be assessed?
Formal neuropsychological tests
How can medial and orbitofrontal lesions be assessed?
Clinical judgement and history taking
Give three examples of tasks that may be included in a formal neuropsychological test?
Tower of London (4 moves)
Stroop test (reading colours)
Rey complex figure test (copy drawing, assess planning)
What are some common causes of executive dysfunction?
CHI
Stroke
Psychiatric conditions (eg. schizophrenia)
Dementias
Focal lesions
Inflammatory
Developmental (eg. autism)
