executive function Flashcards
executive function
the ability to plan actions to reach a goal, guide or control behaviour towards the goal, use information flexibly, think abstractly, and to references
must be exerted in new situations when no preexisting plan/template for how to act exists
required when typical responses must be overridden or inhibited
ie/ saying “you too” to enjoy your meal to serving (the act of stopping this)
also called cognitive control, a term indicating a process in which one is guiding or controlling one’s thought and action
more than one function usually contributes to the performance of executive abilities
it is therefore difficult to link each function to a specific brain region
executive deficits
most commonly observed after damage to the frontal lobe, including white matter connecting frontal regions to other brain areas
difficulties can arise despite normal functioning in other “intellectual processing” area
what skills does completing a task involve
staying on task - with a goal in mind of what we are trying to do
sequencing info
modifying strategies
using knowledge in your plans
monitoring actions - what is the best action to take ie/ using a knife in drawer to spread butter instead of the fork on the counter
goal-directed behaviours
guiding behaviour toward a goal is multifaceted
losing any facet of goal-oriented behaviour can derail the entire plan
completing a task involves a number of skills
these functions rely on patterns of activity within overlapping portions of the frontal lobs, as well as the degree to which it influences or interacts with other regions of the brain - taking info from other regions and deciding what to do with it
frontal lobe damage
causes people to wander off task
can’t stay with assigned task
creating and maintaining a goal task
process that designates which information is task relevant
stroop task- a cue appearing 1.5 seconds before the stimulus indicated whether the person should identify the colour named by the word or the font colour of the word
the lateral prefrontal cortex became active during the cue period, prior to presentation of the stimulus (in response to a cue that designates a specific task set
the greater the degree of activation in the left lateral prefrontal cortex after the cue, the less a competing colour name slower responses
lateral prefrontal cortex became active during the cue period, prior to the presentation of the stimulus (in response to a cue that designates a specific task said)
the greater the degree of activation in the left lateral cortex the cue, the less a competing colour names slowed responses
lateral prefrontal cortex is involved with creating and maintaining a task set
more activation = better at performing task
stroop task: task set for determining ink colour is difficult with the distracting would read words automatically = activation in the lateral prefrontal regions
task set for automatically = activation in the prefrontal regions
when it is harder to maintain a task set, there is greater activation in the lateral prefrontal cortex
what do prefrontal areas do
help us stay on task, especially when irrelevant information is particularly distracting
sequencing and planning
to reach a goal, one must determine what steps to take to attain the goal and in what order those steps must be taken
requires knowing what comes before and what comes after; tasks that have just been accomplished versus those tasks that are about to be performed
dorsolateral prefrontal regions may be important in sequencing items because they support executive processes that act on information being maintained in working memory
choosing a sequencing strategy
another important aspect of sequencing behaviour is the ability to choose which sequence or strategy best allows for a goal to attained
patients with frontal lobe damage are less likely to report that they use strategies
one task used to assess strategy is the Tower of London Task
task switching
the path to a goal is not always simple linear progression
- often there are unexpected twists and turns that require task-switching. ie/ coming into new problems
the classic neuropsychologist test used to examine task switching is the wisconsin task sorting test
Wisconsin card sorting test
neurologically intact people adjust their responses accordingly to new task
people with executive dysfunction perseverate - understand that it is not what they are supposed to be doing anymore, but they can’t pull themselves away
brain areas activated during performance of the wisconsin card sorting task
dorsolateral prefrontal cortex
ventrolateral prefrontal cortex
inferior parietal lobe
temporoparietal association cortex
basal ganglia
brain areas that activate during task-activation
likely to be directed by an executive control system that is independent of the systems that actually perform each of the individual tasks
patients with left frontal lobe damage have a specific deficit in task switching
increasing activity over the left DLPFC via transcranial direct stimulation can augment task-switching abilities
meta-analyses of brain imaging studies also implicate the inferior frontal junction in task switching
task switching and the brain
the location of inferior frontal junction that has ben shown to play a prominent role in switching between tasks
psychological inertia
caused by executive dysfunctions
hard to start an action, but once engaged, equally hard to stop
damage to medial frontal regions, including the supplementary motor area and anterior cingulate
evidence suggests that regions of the medial prefrontal cortex are involved in determining how much “effort” (what you are willing to put in) will be exerted to reach a goal
less connectivity
regions of the anterior cingulate involved in calculating the degree of effort required to obtain an outcome
inhibition: go/no-go task
the person responds by pushing a button when a certain visual stimulus appears (go trials_ and withholds response to other stimuli (No-go trials)
response inhibition is difficult when the no-go trials are relatively rare, because Go trials are expected
in neuroimaging studies, withholding a response has consistently been found to engage a right sided network of frontal brain regions
inhibition: stop-signal task
the person must respond as quickly as possible to a stimulus that appears on the screen
on a minority of trials, very shortly after the stimulus is presented, another signal occurs
- this tone indicates that the response should be aborted
this task activates a similar right-side network of brain regions
regions activated in both tasks include the dorsolateral prefrontal cortex, the anterior cingulate, SMA (pre-SMA), insula, and parietal regions
self-monitoring and evaluation
the ability to evaluate one’s own behaviour is affected by frontal lobe lesions
metacognitive awareness is disrupted in patients with left or right frontal regions
frontal damage, especially right frontal damage, impairs the ability to detect errors and to modify ongoing behaviours to take corrective action
we have a particular set of brain mechanisms that helps us to monitor our performance and detect errors
one initial suggestion was that the anterior cingulate actually detects that an error has been made
- but other evidence suggests that even wehn a person is not aware of an error, an ERN can still be detected
- hence, it may be that the ERN is just providing a rather undifferentiated signal that something is amiss
different regions of the cingulate may be involved in the prediction of the outcome of an action as compared to the evaluation of the outcome
error monitoring and evaluation systems in the brain influenced by individual differences
- anxious people show increased ERN
- Individuals with ADHD show decreases in ERN and Pe
error-related negativity (ERN)
occurs around 100 ms after an error
amplitude increases under conditions in which response accuracy is emphasized
the larger the error, the larger the amplitude of the ERN
a variety of converging evidence suggests that the ERN component arises from rostral regions of the anterior cingulate cortex (ACC)
insula
brain region associated with interoception (the ability to sense the physiological condition of the body)
higher order thinking
describes more complicated aspects of thought
being able to think in an abstract and conceptual manner
the ability to deduce rules or regularity
the ability to be flexible and respond to novelty
activation when reading metaphorical sentences
activity is greater in many areas of prefrontal cortex compared to when reading literal sentences
regions activated during analogical reasoning
includes frontopolar and dorsolateral prefrontal regions, as well as the anterior insula and parietal cortex
distinct areas in the frontopolar cortex activate more for visuospatial analogies than semantic analogies
the pattern suggest both common mechanisms for such reasoning as well as more specific regions that vary with problem type
ventrolateral PFC
needed to retrieve knowledge of rules
dorsolateral PFC
involved in selecting or influencing how rules should be used to guide responding either directly or because it holds rules in working memory
cognitive flexibility
people with executive dysfunction have trouble being cognitively flexible: looking at situations in various ways and/or producing a variety of behaviour
flexibilty is required not only for novel situations, but also when a new reaction must be made to an old situation
orbitofrontal cortex with aiding in flexible behaviour
frontopolar cortex helps reorient potential task goals toward novel situations or opportunities
judgement and decision making
the frontopolar cortex is important for abandoning the current strategy and trying a new one - ie/ if this is not working lets try a new one
medial orbitofrontal regions calculate present vs. future rewards
- research uses the delay discounting paradigm (intertemporal choice task)
- DLPFC engaged when an individual must overcome the temptation to take an immediate reward
working memory and executive function
working memory plays a prominent role in executive function
working memory is needed to:
keep a goal in mind
in order to understand timing and relationships between items and events
in order to create and follow rules, make inferences, and/or understand the relationships between items in the world
ie/ tuning smt out we do not need to hear, focusing attention on what we are wanting to hear
posterior DLPFC/ inferior frontal junction
bias toward sensory or perceptual info that is most task relevant
mid-DLPFC
selection of info in working memory that is most task-relevant
posterior dorsal ACC
late stage response selection; resolves competition between potential responses; overrides prepotent responses
anterior dorsal ACC
response evaluation feedback to DLPFC
