Prefrontal Cortex and Executive Function Flashcards
Functions of the frontal lobe include
motor control, language function (esp Broca’s), higher level cognition/executive functioning
How can the frontal lobe be divided?
cytoarchitecture (layers of cortex); thalamic connections (less common); functional properties (primary, secondary, association areas)
Broadmann’s area 45
Broca’s
Functional distinctions of the frontal lobe are
motor, premotor, and prefrontal cortex
The prefrontal cortex is associated with
Language and executive higher order cognitive function
Lobotomy
removal of tissue
Locotomy
severing of connections (Walter Freeman frontal locotomies)
What were the effects of frontal locotomies?
some people were made calmer and more timid, others had the opposite effect - all changed the personality of the patient eg desire to do things, engagement with environment, capacity to reason through problems, to initiate tasks
Luria’s functional system attributes the anterior unit to what functions?
Planning, executing, and verifying behaviour - ie, executive function
What is executive function?
umbrella term encompassing a huge number of different cognitive domains; planning, executing, and verifying behaviour, thinking skills, social functioning, interrelated processes of goal directed and purposeful behaviour
The dorsolateral prefrontal cortex is responsible for
traditional executive functions: working memory, response selection (and strategy changing), planning and organising, hypothesis generation, flexibly maintaining or shifting set ideas, insight, capacity for moral judgement (right from wrong)
The dorsolateral prefrontal cortex is supplied largely by what artery?
MCA
Working memory tasks assess
capacity to keep information in the mind and use it
Working memory tasks ask the patient to
take something and manipulate it eg remember numbers and repeat them backwards
The medial prefrontal cortex is responsible for
emotional and motivational interface - role in emotional tone or the way emotion is expressed
Medial PFC lesions present with
akinetic mutism (extreme) - functional capacity to move, talk, do, and speak are intact but they lack the motivation or initiation to do anything; apathy, lack of engagement, lack of initiative, lack of self-awareness or capacity to understand own emotions or attribute emotions to others
The medial PFC is largely supplied by which artery?
ACA
How do medial PFC lesions affect self-awareness?
lack of ability to attribute mental state and/or emotions to themselves or others
What is emotional intelligence?
Ability to understand and use emotions appropriately in day-to-day life
What is the orbitofrontal prefrontal cortex responsible for?
highly connected to limbic areas (emotions); inhibition (emotional, cognitive, social); impulsivity
Orbitofrontal prefrontal cortex lesions present with
impulsivity and disinhibition - emotional (crying randomly, laugh inappropriately, greater emotional responses than normal for the situation), cognitive (not stopping a task when they should), or socially (say things they think out loud)
The orbitofrontal prefrontal cortex is supplied by which artery?
ACA and MCA
The frontal lobe is the _____ area of the brain to develop. and one of the ____ to degenerate in ageing
last; first
Because the frontal lobe develops last, what is true of executive functioning?
executive functions are amongst the last abilities to reach maturity (have genetic and environmental factors) with lower order functions developing first and higher order (eg shifting and reasoning) later
What is the idea of a dynamic process of development?
Neural proliferation and pruning based on experiences/stimuli in early life
T/F executive dysfunction and frontal lobe dysfunction are interchangeable terms
F, should not be used interchangeably as executive dysfunction is not a unitary disorder and you don’t have to lesion the PFC to get executive dysfunction (ie connections to/from or cerebellar lesions can result in ED)
General, the prefrontal cortex acts as
a coordinator of executive functioning
T/F lesions that cause executive dysfunction occur only in the frontal lobe
F; can occur in connections, thalamic connections, subcortical or cerebellar lesions can all give rise to executive dysfunction in addition to frontal lesions
What are positive symptoms of executive dysfunction?
more of something: distractability; social disinhibition; emotional instability; perseveration; impulsivity; hypergraphia
What are negative symptoms of executive dysfunction?
less of something: lack of concern; restricted emotion; deficient empathy; failure to complete tasks; lack of initiation
Formal neuropsychological tests tend to be most sensitive to which lesions?
DLPFC lesions
Medial and orbitofrontal lesions are assessed by
difficult to do formally; clinical judgement and hx taking usually from patient AND someone who knows them
Examples of neuropsychological tests of DLPFC lesions
tower of london - balls (planning, impulsivity, inhibition, learning from mistakes, adapting); stroop test - compatible/incompatible coloured words (inhibition); rey complex figure test - copying image (planning, visuospatial)
