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)
ADHD what ?
- Inattention (no organisation or careless mistakes or doesn’t seem to listen etc) or hyperactive/impulsivity (runs/fidgets/excessive talking etc) that interferes with functioning or development
- Begins in childhood but can continue into adulthood (hyperactivity may decrease
- ADHD is a disorder often linked to the frontal lobes (i.e., Zang et al. 2005)OFC/DLPFC/ACC
- Cortical thickness in regions including bilateral DLPFC and OFC, anterior and posterior cingulate cortex (PCC) in adults with ADHD when compared to controls (Proal et al., 2011).
1) Volition
a) What
b) Where?
When there’s a LACK of volition: people can carry out complex activities if instructed to do so, but CANNOT generate the actions (spectrum)
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)
1) Volition
Components & tests
a) motivation: Ability to initiate activity
b) awareness
- Physical Awareness
- Feeling of own body status - Awareness of environment
- Cookie Theft task
- Lack specificity bc it measures a few things SHOULDNT BE USED ALONE IN DX (EG: it measures simultagnosia, Jackson et al. 2006) & Aphasia (Giles et al. 1997) - Social awareness
- iowa scales of personality change
- 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 & Decision making
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
a) what
b) general overview
(3)
- 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
- 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).
- 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)
Maze tracing
a) ADHD
(4)
- ADHD perform badly on this known measure of EF (Grodzinsky & Diamond, 1992)
- May be affected bc they have motor and coordination deficits (Fliers et al. 2008) BUT can get them to trace with finger & subtract this time
- ADHD and IQ – often associated with low IQ but may be bc of these EF deficits that they have low IQ (Biederman et al. 2004) ALSO lack dx power when ADHD have above average IQ. (Mahone, 2010)
- Homatidis (1981) diffs in ADHD and controls but Mcgee (1989) DIDNT; mcgee showed them their errors –> might be due to their memory deficits that they make errors
Tower of London// Tower of Hanoi
a) what
b) Eval
(3)
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
1. 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 - 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// Tower of Hanoi
a) ADHD
- Expression of ADHD will affect task performance i.e. combined type OR just inattention without hyperactivity
- ADHD perform worse more consistently on the Tower of Hanoi than the Tower of London (Willcutt, 2005)
a) WHY =
inhibiting prepotent response > planning (Mikaye, 2000) & (Simmons et al. 2008) key function in ADHD = implusivity; why their performance might be worse in the ToH - ADHD & WM: Klingberg et al. (2002) deficit in WM. Frontal lobe deficits (CE)
- ADHD & visuospatial deficits (Bennett et al. 2005)
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
- 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).
Iowa Gambling task
a) What
b) Eval (4)
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.
- type of emotional decision-making (Pecchinenda 2006) (OFC)
- learn to avoid bad decks
EVAL
A, Practicality
1. 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
2. Lesions to the VMPFC are reliably and specifically linked with defective performances on the IGT (Lezak, 2012) –> validity of IGT as a measure of decision making associated with frontal lobe dysfunction
BUT
3, 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)
4. 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
Iowa Gambling task
a) ADHD (4)
- ADHD can be detected in IGT (Becchara, 2007)
BUT many factors will affect this: Inattentive vs hyperactive/impulsive symptoms (Beulow & Suhr, 2008) - Known to have emotional decision making (Takahashi 2013) =i.e. impulsive & reckless
- ADHD v comorbid with anxiety & depression (E.G. Tsang, 2012)
- ADHD & WM: Klingberg et al. (2002) deficit in WM. Frontal lobe deficits (CE)
Iowa Gambling task
a) where?
- Insula and cingulate cortex (emotional state)
- dlPFC/vmPFC/OFC (coupling memory & emotion)
(Li et al. 2009)
Purposeful action
a) What?
a) Productivity
b) Flexibility: capacity to shift one’s plans
c) Perseveration
Purposeful action: Flexibility
a) What?
b) Eval
(4)
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
1) IQ affects the scores BUT no effect of gender (Strauss et al. 2006)
B. Brain
2) 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)
3) When compared with healthy patients, the frontal lobe damaged patients make more preservative errors (Grafman, 1990)
BUT
“caution against using the WCST to identify lesion sites OR as a “marker of frontal lobe dysfunction”
4) 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)
- 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
Neurorehabilitation - overview
’Esposito & Gazzaley, (2006) – cognitive tx for ADHD
- **3 ways of treating
1) Environmental manipulations= Focuses on factors external to patient, such as decreasing distracters, simplifying task demands or allowing more time
2) Compensatory techniques =Allows patients to accomplish a task in a new manner that minimizes the impaired skills
3) Direct interventions = most of the executive rehabilitation literature focus.
Direct intervention (example & where used)
Attention process training (ATP) = Practice on graded tasks of attention will promote recovery of damaged neural pathways & retrain attentional abilities.
ADHD:
- Shalev, (2007) - Children & ADHD on APT —> APT was effective for ADHD (readingcomprehension/ inattentiveness measures)
d. Tamm et al. (2010) –> ALSO found ^ (neither a RCT tho)
e. Klingberg (2005) – not apt (but no RCT on APT/EF/ADHD yet)
- This study shows that WM can be improved by training in children with ADHD.
- WM IS A COMPONENT OF EXECUTIVE FUNCITONING (Downson et al. 2004)
F. all supported by neuroimagining (Beauregard & Levesque, 2006) i.e. before and after activation and attention training.
