Executive Function Flashcards
Executive functioning - overview & definitions (3)
1) Volition - process of using one’s will; deciding if they want to do something or not. Capacity for intentional behaviour.
a. MOTIVATION - Ability to initiate activity
b. SELF AWARENESS - Awareness of oneself psychologically, physiologically and in relation to one’s surroundings
2) Planning + decision making - thinking of steps needed to carry out a particular behaviour/goal. Weigh choices & impulse control
3) Purposive Action - Translation of intention into productive self-serving activity
^Self regulation - governing of oneself to regulate behaviours.
a. FLEXIBILITY - The ability to shift a course of thought or action according to the demands of the situation
b. PRODUCTIVITY - give advise about performing an activity, but do not perform the activity themselves
Executive functioning - what / where? Overview
- Executive function = are a set of processes that all have to do with managing oneself and one’s resources in order to achieve a goal.
- is a LOT of different things = hard to measure & actually segregate each component
- deficits normally from frontal lobe problems (can also be other areas which may contribute to it though)
VOLITION
what & measure precaution? & where?
when there’s a LACK of volition: people can carry out complex activities if instructed to do so, but CANNOT generate the actions. - on a spectrum
Components: motivation & self awareness
WHEN MEASURING NEED TO:
- distinguish between unmotivated/undirected from FROM aspects of character i.e. laziness, childish dependencies OR psychiatric disorders (depression or SZ) (Fossatti et al. 1999)
very few tests for volitional capacity –> need to rely on observations and the reports from caregivers
REGION
- mPFC in human volition, it is obvious that this part of the brain does not operate in isolation. The parietal cortex plays an important role as does the anterior cingulate cortex (Brass et al. 2013)
VOLITION: motivation
what/measure (3)
- Ability to initiate activity
- ask the patient what they do for fun (& when they last did that activity)
- choice reaction task/ scatter pennies on the table and blindfold them & get them to pick them up. May show volition probs (Heilmen & Watson, 1991)
VOLITION self-awareness
what/measure/eval (3)
3 types: physical awareness & awareness of others and surroundings
A. PHYSICAL AWARENESS
– Feeling intact when body is actually impaired; ask about career plans & see if they are feasible i.e. they’re not blind if they say pilot
B. AWARENESS OF ENVIRONMENT
Cookie Theft task (Goodglass, 2000)
- Girls start talking before boys; if looking @ in children girls might perform better due to better lang NOT cos EF
- Lack specificity bc it measures a few things SHOULDNT BE USED ALONE IN DX (for example: it measures simultagnosia, Jackson et al. 2006 & Aphasia (Giles et al. 1997)
C. SOCIAL AWARENESS
Iowa Scales of Personality Change
- Answered by an informant (close informant who has known the person before and after the accident). Measures degree of change**
- Factor analysis draws up 2 factors that are v related to volition: diminished motivation & disturbed social behaviour
- older caregivers (i.e. spouses) are biased in their marking due to their own EF problems (i.e. their observations are impaired) –> large body of inconsistent agreements of inofrmants & actual patients performance (Yasuda et al. 2004)
- able to discriminate frontal from non-frontal lesioned patients (Malloy, 2005)
Planning and Decision making // Goal directed behaviour
What/measure overview
- need to look ahead & weigh choices
- impulse control and reasonable memory functions are required
Measures:
a. Maze Tracing
b. ToL/ ToH
c. IGT
Maze tracing - what / eval (A = 3/B = 3)
Tests: planning
- Porteus Maze Tests
- Need to think of alternative strategies
- Need preliminary foresight into the right way around the maze in order to get through it
EVAL
A. Practical
- Education:
Ardila + Rosselli (1989): education effects.
BUT
1/3 of sample had less that 4 yrs schooling.
SO –> Weis (1980) - illiterate vs 6 yrs schooling. FOUND illiterate didn’t plan before starting maze. Schooling was able to plan
- Strong correlatiopns between this and the ToL task - has big planning input (Krikorian et al. 1994)
- If concerned about motor problems in the task = subtract the time it takes them to trace over the pre-drawn maze from the time it takes to complete (Levin et al. 1991).
- *For example if you wanted to look@ planning in someone with stroke affecting their hand – eye coordination (Meadmore, 2017)
B. Brain
- Deficits on this maze also found in SZ who have long been considered to have Executive-frontal lobe cognitive dysfunction (Mubarik, 2016)
- Was able to separate TBI in the frontal lobe vs TBI in the posterior parts of brain (even when motor speed was taken into account GOOD BC POSTERIOR = MOTOR; ataxia) (Levin et al 1991)
- also good @ predicting severity – Meier et al. (1982) – those who scored above a certain amount on these mazes a few week after stroke, made significant gains in lost motor functions. BUT those who scored below = showed little spontaneous improvement
Tower of London// Tower of Hanoi - what/eval
Tests: planning
- Hanoi: need to rearrange the rings in increasing order of size
- London: Need to rearrange coloured rings in a new position using the minimum number of moves
- *Achieve end goal = minimal moves as possible
EVAL
A. Practical
- sex differences in strategies = males use visuospatial abilities & females rely on executive functions (Boghi et al. 2006)
- Confounds: although this test is usually used to assess planning abilities – confounds may also be: working memory, response inhibition & visuospatial memory (Carlin et al. 2000)
- ToL & ToH DONT MEASURE SAME THING –> ToL (planning) & ToH (inhibiting a proponent response)
a. Correlation isn’t high (Humes, 1997)
b. (Miyake et al. 2000) who showed that response inhibition contributes to success in ToH - *shouldn’t be used interchangeably
B. Brain
- patients with frontal lobe damage = had normal planning times (Carlin et al. 2000) BUT compared with healthy comparison subjects = patients with focal lesions made more moves// trial and error strategy + were slower to arrive @ a solution
- tower of london performance was correlated with dorsal lateral prefrontal cortex activation; poorer performance in those with lateral prefrontal lesions (Yochim et al. 2007) (& shown to active DLPFC)
- Requires WM thus some dementia patients might fail to complete the task (Gel et al. 2001)
ToL where? (2)
- Dorsal lateral prefrontal cortex AND superior parietal lobe (Newman et al. 2003)
- more activation in the dlPFC as task gets harder
- SPL = bc it’s also a spatial task (need spatial attention) - Wagner et al. (2006)
- DLPFC , VLPFC AND rostrolateral prefrontal cortex as well as in the parietal and premotor cortex.
- Rostrolateral increase over planning levels - only region associated w planning specifically.
- was put down to the RLPFC specialised role involved with keeping in mind a higher order goal while prosecuting sub-goals in the sense of “branching” which has been implicated with the RLPFC Burgess et al. (2005).
- ^ Used a event related fMRI (better able to identify state-item interactions & thus, may pick up better on subgoal interactions of the RLPFC
- parietal - might be spatial attention (Mirsky, 1989)
Iowa Gambling task
What/ eval
Tests: Planning & emotional decision making
- Maximize monetary gain: told to avoid “bad” decks. 2 types of decks –> a. big wins but big losses (overall loss) & small wins/losses.
- This type of decision-making is motivated by reward and has been regarded as a type of emotional decision-making (Pecchinenda 2006) (OFC)
- learn to avoid bad decks
EVAL
A, Practicality
- criticisms for its complexity (Li et al. 2010)
^ but this makes it more like real life; simpler decision making tasks dont pick up on vmPFC damage
B. Brain
- Lesions to the VMPFC are reliably and specifically linked with defective performances on the IGT (Lezak, 2012) provides evidence of the validity of IGT as a measure of decision making associated with frontal lobe dysfunction
BUT
- anxiety and depression will affect the persons performance on this task E.G. high anxiety = poor decision making (Miu et al. 2008) & depressed patients expect punishment after obtaining large reward = difficulty modulating behaviour (Must, 2013)
- SZ are impaired but not due to their decision making abilities BUT due to their impaired memory abilities rather than problems with impulsivity/ decision making (Premkumar et al. 2008) = wont differentiate those with WM problems & ef problems
IGT where?
Brain Regions
- DLPFC/VMPFC/OFC in healthy ppts.
Lesion studies
a. Bechara (1994) = vmPFC lesions impaired (not dlPFC tho)
b. Manes (2002) dlPFC lesions imapired & OFC not impaired
c. Fellows & Farah (2005) = both vmPFC and dlPFC impaired
WHY THE DIFFERENCE
a. Difference behavioural indicators of poor decision making as an aspect of ppt selection = Bechara – included those with presence of real life problems BUT other 2 didn’t require behavioural deficits in real life.
b. Manes excluded ppts with current or past psychotic diagnoses but the others didn’t (E.G. OCD AND SZ both have probs w vmpfc and dlpfc = thus leading to impaired results on the IGT) (Cavallaro et al. (2003)
Consensus that it’s in the prefrontal cortex in planning/decision making (Beulow & Suhr, 2009) BUT so many different factors will affect this (history, emotional/current state, other symptoms etc)
Purposeful action
made up of?
a) Productivity
b) Flexibility: capacity to shift one’s plans
c) Perseveration
Purposeful action
Flexibility/ perseveration important to?
- Distinguish between attentional deficits. Perseveration is a “stickiness” in thinking + are an inability to STOP hat currently doing.
- Or if they have memory loss + cannot remember previous or ongoing things
- Intellectual deficits should be looked @ too
Flexibility
Purposeful action
A. Wisconsin Card Sorting test:
- Tests ability to shift category, that is to change the sorting rule = “set shifting”
Participant not told this but asked to match the card in the lower deck with the upper deck.
- IDEA IS THAT YOU CHANGE YOUR STRATEGY ASAP
EVAL - Top ranked test for EF
A. Practicality
- Age effects are well documented - reductions in processing speeds & impaired wm (Friscoe et al. 1997)
- IQ affects the scores BUT no effect of gender (Strauss et al. 2006)
B. Brain
- Functional neuroimaging studies have supported a major role of the frontal lobe in the WCST; Earned a rep for being good for frontal lobe damaged patients (Hazlett et al. 2015)
- When compared with healthy patients, the frontal lobe damaged patients make more preservative errors (Grafman, Jonas + Salazar, 1990)
BUT
…“caution against using the WCST to identify lesion sites OR as a “marker of frontal lobe dysfunction”
- 20 diffuse TBI patients (with probable frontal injury) = only 8 made more preservative errors than normals (Martzke et al. 1991
- Lombardi et al. (1999) –> both frontal and non frontal lobe patients had high levels of perseverative responses
PET scanning showed strong association with dorsolateral frontal – circuit dysfunction (not just dlpfc)
So, this test is sensitive to frontal damage BUT it does not localise lesions nor is it a reliable brain damage screen.
Flexibility
Where?
- Buchsbaum (2005) meta-analysis = bilateral pfc +anterior cingulate cortex & inferior parietal lobe
- Lie et al. (2006) Increasing task complexity (A > B > C) is associated with increasing activation within right prefrontal cortex and the anterior region of the anterior cingulate cortex.
- Grafman (1990) found a left pfc dominance?
WHY THE VARIATION?
Stuss et al (2000)
- demonstrated that patients with either left or right
focal prefrontal lesion were impaired on the ‘‘perseveration to the preceding response’’ score in the WCST, but the right prefrontal group was impaired more severely than the left prefrontal group
- DISCREPENCY = associated with verbal mediation during the performance of the WCST
a. Several neuroimaging studies suggested that when abstract—that is, difficult to verbalise— figures or colours are used in the tasks and covert verbalisation is effectively prohibited, the right dorsolateral PFC is differentially activated in relation to the attentional set shifting (E.G Nagahama, 2001)
b. In contrast, the bilateral PFC is active during the performance of the original WCST
**These findings suggest that although the essential process of the visual dimensional changes is mediated by the non-verbal systems in the right PFC, the set shifting in the WCST could be also performed through the verbal systems in the left hemisphere. The metaanlysis didnt account for this hence the bilateral
