Executive functioning

1
Executive functioning

• Dr. Elizabeth Sheppard

Developmental Cognitive Neuropsychology (C8CLDC)
Child Clinical Neuropsychology (C8DCHN)
2
Objectives

• Be able to explain what is meant by executive
  functions (defining/problems)
• Give examples and explain cognitive tests used to
  test EF
• Discuss the strengths and limitations of EF
  measures in adults and children
• Explain how EF develops in typical children
• Discuss the extent to which adult models of EF
  can be applied to children using evidence from
  typically developing children and children with
  acquired brain lesions

3
What are Executive functions?

• Set of processes that underlie flexible
  goal-directed behaviour (e.g. planning,
  inhibitory control, attentional
  flexibility,working memory), Bianchi (1922)
• High-order control processes
• Domain general i.e. operate across cognitive
  systems/ modalities
• This definition is provisional under-specified
  we dont know much about this area of cognition!

4
How many components of Executive abilities are
there?

• Lezak 1995 - Suggests there are 4 components of
  Executive function
• Volition
• Planning
• Purposeful behaviour
• Effective performance
• Stuss 1987 - Identifies a number of associated
  skills necessary for goal-directed behaviour
• Ability to shift from one concept to another
• Ability to modify behaviour in light of new info
• Ability to synthesise integrate isolated
  details into coherent whole
• Ability to manage multiple sources of information
• Ability to make use of relevant acquired
  knowledge

5

How many components of Executive abilities are
there?

• Anderson et al. (2001) propose 3 separable but
  unified components of EF
• 1.)  Attentional control selective attention and
  sustained attention
• 2.)  Cognitive flexibility working memory,
  attentional shift, self-monitoring, and
  conceptual transfer
• 3.)  Goal setting initiating, planning and
  organisation, generating and implementing
  strategies for problem solving, and strategic
  behaviour

6
What is Executive Dysfunction (dysexecutive
syndrome)?

• 1.) Behavioural features - Poor self-control,
  impulsivity, erratic careless responses, poor
  initiation of speech, inflexibility (Lezak, 1995)
• Case of Phineas Gage quiet family man yard
  long spike forced through his head
• Memory, language motor functions in tact
• Complete personality change

7
What is Executive Dysfunction (dysexecutive
syndrome)?

• 2.) Cognitive features People with Executive
  Dysfunction exhibit poor performance on tasks
  which require one to use Executive Abilities
• Tasks developed for use with adult participants
  with brain injuries
• Large range of tasks tapping into various aspects
  of EF

8
Measures of EF - Wisconsin Card Sort

• Cards vary along several dimensions
• Sort given feedback infer rule
• Experimenter changes rule
• Change strategy infer new rule
• Involves problem solving cognitive flexibility

9
Measures of EF - Tower of Hanoi

• Move all hoops from left peg to right peg without
  putting larger hoop on top of smaller
• Involves attentional shifting, planning,
  inhibition

10
Measures of EF - Stroop Task

• Read colour words
• Either congruous or incongruous
• Take longer if incongruous
• Involves selective attention inhibition

RED BLUE GREEN YELLOW
RED BLUE GREEN YELLOW
11
Measures of EF - Verbal Fluency Task

• Generate as many words as possible in one
  minute that begin with the letter N ?
• Requires the use of a self generated strategy
• Time limit imposed

12
Measures of EF - Rey Figure Test

• Copy figure as accurately as possible
• Accuracy score measures spatial organisation
• Organisational strategy score measures strategic
  decision making
• Memory test also used sometimes

13
Measures of EF - Self-ordered Pointing task

• Present series of arrays with a number of
  different elements
• Point to different element in each array until
  all pointed to
• Spatial location of elements changes in arrays
• Involves working memory and strategic planning

14
Problem with measurements

• Some question over reliability of measures e.g.
  WCST (Pennington et al.)
• Discriminant validity the ability to
  discriminate between distinct constructs
• Tasks tap multiple EF components so unclear which
  EF causes poor performance
• Tasks also involve non-EF processes so are poor
  at differentiating between EF deficits and non-EF
  deficits

15
What is executive dysfunction?

• 3). Biological features
• The Frontal Metaphor
• Association noted between tasks which involve EF
  processes and damage to the pre-frontal cortex
• Neuropsychologists may say an individuals
  symptoms look frontal, without knowing the
  nature of the brain damage

16
What is executive dysfunction?

• Studies documenting effects of frontal lesions
  report heterogeneous range of tasks behaviours
  disrupted
• But all require goal-directed behaviour, usually
  in novel contexts e.g. Cohen Servan-Schreiber,
  1992
• Patients with lesions fail despite understanding
  goal of task due to perseveration, impersistence,
  intrusions of task irrelevant behaviour or lack
  of initiative
• Cannot be attributed to more basic deficit in
  memory, perception or language comprehension

17
What is executive dysfunction?

• Evidence from neuroimaging and neuroanatomical
  studies suggests that EF processes are associated
  with the PFC (Rakic, Bougeois, Zecevic, Eckenhoff
  Goldman-Rakic, 1986)
• Strong evidence from PET scan studies showing
  association between WCST and activity in the PFC
  in normal and schizophrenic patients (Weinberger
  et al. 1994)

18
How does executive function relate to IQ?

• Effects of adult frontal lesions on IQ appear to
  be negligible (Kolb Wishaw, 1990)
• Frontal lobes may be important for fluid
  intelligence but less important for crystallised
  intelligence
• Duncan et al. (1995) patients with frontal
  lesions showed disparity between scores on
  Wechsler IQ test Culture Fair IQ test those
  with lesions elsewhere/ no lesions did not

19
Why might damage occur to the PFC?

• Acquired adulthood
• Acquired childhood
• Congenital (developmental disorder)

20
Why study Executive Functioning in children?

• Are adults and children qualitatively different
  in terms of EF? (frontal metaphor)
• Some EF behaviours may actually be evident in
  childhood but redundant in adulthood (Smith et
  al., 1992)
• Gets around discriminant validity problem in
  adult tasks simpler tasks can be used.
• We need to know about typical development of EF
  skills to help us understand developmental
  disorders that involve EF impairments.

21
Stages of Executive development

• Frontal lobes originally thought to be
  functionally silent during childhood EFs not
  measurable until second decade
• This has been refuted now e.g. Diamond Doar
  argue cognitive skills necessary for EF are
  demonstrated in young children
• Studies have shown frontal activity during even
  infancy
• e.g. Chugani et al. (1987) measured local
  cerebral metabolic rates of glucose found
  evidence of frontal activation in infants of 6
  months

22
Stages of Executive development

• Older children make age-related gains on battery
  of EF tasks
• Levin et al. (1991) gains in concept formation,
  mental flexibility, planning problem solving
• Researchers agree that EF skills produce
  stage-like development
• Some EFs appear to mature earlier than others
  supporting multidimensional nature

23
Stages of Executive development

• Welsh, Pennington Groisser (1991)
• Studied children aged 3-12 yrs on various EF
  measures argue for 3 distinct developmental
  stages
• Age 6- Competence with simple planning and
  organised visual search.
• Age 10- Set maintenance, hypothesis testing, and
  impulse control attained.
• Adolescence- Complex planning, motor sequencing,
  and verbal fluency
• In general, greatest development occurs in middle
  childhood with slower development continuing later

24
EF development and frontal lobe development

• Evidence for direct link between frontal
  development EF from studies of object
  permanence in monkeys
• Object permanence requires working memory
  inhibition develops in children around 7 months

• Diamond Goldman-Rakic
• (1989) animals with lesions
• to parietal lobes passed A
• not B task those with frontal
• lesions did not

25
EF development and frontal lobe development

• Evidence suggests improvement in EF during
  childhood corresponds with growth spurts in
  frontal lobe development
• Bell Fox (1992) EEG changes in frontal lobes
  during 1st year of life correlate with length of
  delay for response in delayed response tasks
• However, some argue EF maturation reflects
  integrity of cerebral development throughout the
  brain or EF maturation dependent on emergence of
  other cognitive abilities (see Anderson et al.)
• Skill learning approach (similar to interactive
  specialisation account) frontal cortex
  consistently involved in acquisition of new
  skills knowledge from early on in life plays
  role in organising other parts of cortex (e.g.
  Thatcher, 1992)

26
Children with acquired frontal damage case
studies

• If children with frontal lesions different from
  adults, problems for frontal metaphor
• Children with acquired frontal damage are rare so
  case study approach used for studying frontal
  injuries in children
• Therefore, note that limitations of case studies
  apply here
• Lack of consistent measures across cases
• Ascertainment biases (bias in sampling
  non-random)
• Nevertheless case studies produce fairly
  consistent findings
• N.B. Very important to consider cases within
  developmental perspective

27
Children with acquired frontal damage case
studies

• Williams Mateer (1992) DR- 811, falling beam
• - EEG MRI showed damage to frontal region.
• Failure to maintain intellectual ability after
  injury
• Social language problems, but Verbal and
  non-verbal memory intact
• Difficulty with acquisition of new information
• Little spontaneous activity
• Tantrums, aggression, unpredictable outbursts,
  impulsivity

28
Children with acquired frontal damage case
studies

• Williams Mateer (1992) - SN age 11, fell from
  tree
• - CT scan showed bilateral frontal lobe damage.
• - Dramatic changes in PIQ
• - Problems with sustained attention,
  visuo-spatial planning, motor control
• - Inappropriate problem solving strategies,
  -Verbal reasoning and expressive vocabulary good,
  but not verbal inductive reasoning.
• - Tantrums, aggressive, inappropriate laughter,
  eating problems

29
Children with acquired frontal damage case
studies

• Age 12-probs with mental flexibility, sustaining
  attention, verbal fluency, perceptual
  organisation.
• Age 13-Bi-frontal abnormalities evident (EEG).
  Superior verbal ability, non-compliant behaviour
• Age 15- probs with inhibiting verbal responses,
  extreme literalness, compulsive attention to
  detail, directing attention, high distractibility.

30
Children with acquired frontal damage case
studies

• Marlowe (1992) - PL 311, lawn dart
• Age 5
• - good intellectual levels
• - good simultaneous but poor sequential
  processing
• - Verbal processing excellent, but needed
  instructions repeated extensively
• Age 6
• - similar intellectual level (but reduced
  efficiency in learning new info)
• - A number of other cognitive deficits were
  evident poor anticipatory behaviour, verbal
  understanding, visuo-spatial organisation and
  production, distractible, inhibition problems,
  perseveration.

31
What do childhood case studies tell us?

• Frontal lesions have dramatic and lasting effects
• Suggests that effects of frontal lesions are NOT
  silent, temporary, or radically different than
  adults (support frontal metaphor)
• Severity and time of insult are important
• - down stream effects
• Some of the symptoms are similar to those for
  developmental disorders (e.g. conduct disorder,
  ADHD), although they do not meet all criteria
  seems to support frontal metaphor for
  developmental disorders

32
Summary

• EFs multi-componential processes underlying
  flexible goal-directed behaviour
• EFs associated with PFC
• Number of EF tasks/ but problematic
  discriminant validity
• Child research gets around this to some extent
• Case studies suggest EFs similar in children and
  adults

33
References

• Anderson, V., Northam, E., Hendy, J., Wrennall,
  J. (2001). Developmental Neuropsychology A
  Clinical Approach. Hove Psychology Press.
• Bell, M. A., Fox, N. A. (1992). The relations
  between frontal brain electrical activity and
  cognitive development during infancy. Child
  Development, 63, 1142-1163.
• Bianchi, L. (1922). The Mechanism of the Brain
  and the Function of the Frontal Lobes. Edinburgh
  Livingstone.
• Chugani, H. T., Phelps, M. E., Mazziotta, J. C.
  (1987). Positron emission tomography study of
  human brain functional development. Annals of
  Neurology, 22, 287-297.
• Cohen, J. D., Servan-Schreiber, D. (1992).
  Context, cortex, and dopamine A connectionist
  approach to behavior biology in schizophrenia.
  Psychological Review, 99, 45-77
• Diamond, A., Doar, B. (1989). The performance
  of human infants on a measure of frontal cortical
  development The delayed response task.
  Developmental Psychology, 22, 271-294
• Diamond, A., Goldman-Rakic, P. (1989).
  Comparison of human infants and rhesus monkeys on
  Piagets AB task Evidence for dependence of
  dorsolateral prefrontal cortex. Experimental
  Brain Research, 74, 24-40.
• Duncan, J., Burgess, P., Emslie, H. (1995).
  Fluid intelligence after frontal lobe lesions.
  Neuropsychologia, 33, 261-268.

34
References

• Glosser, G., Goodglass, H. (1990). Disorders in
  executive control functions among aphasic and
  other brain-damaged patients. Journal of Clinical
  and Experimental Neuropsychology, 12, 485-501.
• Kolb, B., Wishaw, I. Q. (1990). Fundamentals of
  Human Neuropsychology. New York W H Freemont
  Company.
• Levin, H. S., Culhane, K. A., Hartmann, J.,
  Evankovich, K., Mattson, A. J., Howard, H.,
  Ringholz, G., Ewing-Cobbs, L., Fletcher, J. M.
  (1991). Developmenal changes in performance on
  tests of purported frontal lobe functioning.
  Developmental Neuropsychology, 7, 377-395.
• Lezak, M. (1995). Neuropsychological Assessment.
  (3rd edn.). New York Oxford University Press.
• Luciana, M., Nelson, C. (1988). The functional
  emergence of pre-frontally guided working memory
  systems in four-to-eight year old children.
  Neuropsychologia, 30, 273-293.
• Marlowe, W. B. (1992). The impact of a right
  prefrontal lesion on the developing brain. Brain
  and Cognition, 20, 205-213.
• Mateer, C. A., Williams, D. (1991). Effect of
  frontal lobe injury in childhood. Developmental
  Neuropsychology, 12, 95.
• Rakic, P., Bourgeois, J.-P., Zecevic, N.,
  Goldman-Rakic, P. (1986). Concurrent
  overproduction of synapses in diverse regions of
  the primate cortex. Science, 232, 232-235.

35
References

• Smith, S. D., Kates, M. H., Vriezen, E. R.
  (1992). The development of frontal lobe
  functions. In S. J. Segalowitz I. Rapin (Eds.).
  Handbook of Neuropsychology vol 7. Child
  Neuropsychology. Amsterdam Elsevier.
• Stuss, D. T. (1987). Contribution of frontal lobe
  injury to cognitive impairment after closed head
  injury Methods of assessment and recent
  findings. In H. S. Levin, J. Grafman, H. M.
  Eisenberg (Eds.). Neurobehavioural Recovery from
  Head Injury. New York Oxford University Press.
• Thatcher, R. W. (1991). Maturation of the human
  frontal lobes Physiological evidence for
  staging. Developmental Neuropsychology, 7,
  397-419.
• Thatcher, R. W. (1992). Cyclic cortical
  reorganisation during early childhood. Special
  Issue The role of frontal lobe maturation in
  cognitive and social development. Brain and
  Cognition, 20, 24-50.
• Weinberger, D. R., Behrman, K. F., Gold, J.,
  Goldberg, T. (1994). Neural mechanisms of
  future-oriented processes In vivo physiological
  studies of humans. In M. M. Haith, J. B. Benson,
  R. J. Roberts, N. F. Pennington (Eds.). The
  Development of future-oriented processes.
  Chicago University of Chicago Press.
• Welsh, M., Pennington, B. F., Groissier, D. B.
  (1991). A normative-developmental study of
  executive function A window on prefrontal
  function in children. Developmental
  Neuropsychology, 7, 131-149.
• Williams, D., Mateer, C. A. (1992).
  Developmental impact of frontal lobe injury in
  middle childhood. Brain and Cognition, 20,
  196-204.