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What are executive functions?

One conceptualisation (Miyake et al., 2000):
• The ability to over-ride automatic behaviour in
order to deal with novel situations
• The ability to switch flexibly between tasks
• The ability to carry out a task while holding in
mind other goals


The prefrontal cortex

• The prefrontal cortex can be ‘divided’ in many
• One common subdivision of the prefrontal
cortex is into three ‘regions’:
– Dorsolateral prefrontal cortex
– Orbitofrontal cortex
– Mediofrontal cortex


The frontal lobes

The frontal lobes are richly connected with
other cortical and subcortical regions of the
brain. Thus, we should not consider the
functions attributed to the frontal circuits or
regions to be solely localised or mediated by a
specific circuit or region.


The dorsolateral prefrontal cortex

The DLPFC and its circuitry is involved in
higher order cognitive operations.
• This circuit is often labelled the ‘executive’
circuit, however it’s important to recognise
that executive functioning is also implicated in
the mediation of emotional, motivational, and
social behaviour.


Deficits following damage to dorsolateral prefrontal cortex

Deficits following damage to the dorsolateral
prefrontal cortex may include:
– Working memory
– Planning, task-setting, and problem-solving
– Sequencing
– Selective and sustained attention
– Perseveration – “getting stuck”
– Inhibition
– Cognitive flexibility


Working memory

• Alan Baddeley’s working memory model
can be thought of as a slightly different
way to characterise short-term memory
• He argued that working memory is a
system that provides temporary storage
for information that is currently being used
in some conscious capacity (Baddeley,


Baddeleys theory working memory visuospatial sketchpad

System for rehearsing visual information


Baddeleys theory working memory PHONOLOGICAL loop

System for rehearsing verbal information


Baddeleys theory working memory: Central executive

System for controlling how the ‘slave’ systems like
the visuospatial sketchpad and the phonological
loop are used


Baddeleys theory: Articulatory loop

“Inner voice” used during rehearsal of verbal
• The articulatory loop involves speech.


Baddeleys theory: Phonological store

“Inner voice” used during rehearsal of verbal
• The articulatory loop involves speech.


Working memory: The word length effect

– Short words are easier to (briefly) memorize
than long words
– wit, sum, harm, bay, top  4.5 words
– university, opportunity, aluminum,
constitutional, auditorium  2.6 words
• A crucial factor that
determines the
memory span is
how long it takes to
say a word


Working memory: Evidence for the neural architecture

Delayed match-to-sample tasks with monkeys
(Goldman-Rakic, 1992)
• Monkeys with lesions to the frontal cortex
(DLPFC) weren’t able to perform this task


Neuropsychological measures sensitive to
dorsolateral frontal damage

Digit span backwards, backwards 7’s, N-Back
(working memory)
• F-A-S test (individuals may repeat items or get stuck)
• Tower of Hanoi / Tower of London (tasksetting/planning,
sequencing, problem-solving)
• Stroop (inhibition)
• Wisconsin card sort (cognitive flexibility


The orbitofrontal cortex

In basic terms, the orbitofrontal cortex and its
circuitry is involved in the mediation of
emotional and social responses. It is
responsible for executive processing of
emotional stimuli.


The orbitofrontal cortex deficits

Deficits following damage to the orbitofrontal cortex
may include:
– Emotional lability
– Diminished social insight
– Socially inappropriate behavior, esp. conversational skills
– Difficulties with changing reinforcements
– Lack of sensitivity to future outcomes, both positive and
– Lack of empathy


Neuropsychological measures sensitive to
orbitofrontal damage

Family/caregiver reports of social behaviour,
empathy, aggression
• F-A-S test (individuals may give socially
inappropriate answers)
• Bechara’s Gambling task


The mediofrontal cortex

This prefrontal region is believed to support a
number of overlapping functions, including:
– Response monitoring (control and monitoring of
– Error detection
– Deciding between competing responses
– Motivation or drive behaviour


Deficits to the mediofrontal cortex

• Deficits following damage to the mediofrontal
cortex may include:
– Apathy
– Akinesia
– Difficulties with emotion: flat affect
– Difficulties with decision-making
– Diminished verbal output


Neurospsychological measures sensitive to mediofrontal damage

Family/caregiver reports (apathy)
• Questionnaires, scales measuring motivation
• Reaction time (individuals with damage to this region
may be slower on speeded tasks)