Presentation on theme: "Executive functioning"— Presentation transcript:
1 Executive functioning Dr. Elizabeth SheppardDevelopmental 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 EFDiscuss the strengths and limitations of EF measures in adults and childrenExplain how EF develops in typical childrenDiscuss 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 processesDomain general i.e. operate across cognitive systems/ modalitiesThis definition is provisional & under-specified – we don’t know much about this area of cognition!
4 How many components of Executive abilities are there? Lezak Suggests there are 4 components of Executive function:VolitionPlanningPurposeful behaviourEffective performanceStuss Identifies a number of associated skills necessary for goal-directed behaviourAbility to shift from one concept to anotherAbility to modify behaviour in light of new infoAbility to synthesise & integrate isolated details into coherent wholeAbility to manage multiple sources of informationAbility 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 attention2.) Cognitive flexibility: working memory, attentional shift, self-monitoring, and conceptual transfer3.) 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 headMemory, language & motor functions in tactComplete 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 AbilitiesTasks developed for use with adult participants with brain injuriesLarge range of tasks tapping into various aspects of EF
8 Measures of EF - Wisconsin Card Sort Cards vary along several dimensionsSort & given feedback – infer ruleExperimenter changes ruleChange strategy & infer new ruleInvolves 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 smallerInvolves attentional shifting, planning, inhibition
10 Measures of EF - Stroop Task Read colour wordsEither congruous or incongruousTake longer if incongruousInvolves selective attention & inhibitionREDBLUEGREENYELLOWREDBLUEGREENYELLOW
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 strategyTime limit imposed
12 Measures of EF - Rey Figure Test Copy figure as accurately as possibleAccuracy score measures spatial organisationOrganisational strategy score measures strategic decision makingMemory test also used sometimes
13 Measures of EF - Self-ordered Pointing task Present series of arrays with a number of different elementsPoint to different element in each array until all pointed toSpatial location of elements changes in arraysInvolves 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 constructsTasks tap multiple EF components so unclear which EF causes poor performanceTasks also involve non-EF processes so are poor at differentiating between EF deficits and non-EF deficits
15 What is executive dysfunction? 3). Biological featuresThe “Frontal Metaphor”Association noted between tasks which involve EF processes and damage to the pre-frontal cortexNeuropsychologists may say an individual’s 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 disruptedBut… all require goal-directed behaviour, usually in novel contexts e.g. Cohen & Servan-Schreiber, 1992Patients with lesions fail despite understanding goal of task due to perseveration, impersistence, intrusions of task irrelevant behaviour or lack of initiativeCannot 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 intelligenceDuncan 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 adulthoodAcquired childhoodCongenital (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 decadeThis has been refuted now – e.g. Diamond & Doar argue cognitive skills necessary for EF are demonstrated in young childrenStudies have shown frontal activity during even infancye.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 tasksLevin et al. (1991) – gains in concept formation, mental flexibility, planning & problem solvingResearchers agree that EF skills produce stage-like developmentSome 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 stagesAge 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 fluencyIn 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 monkeysObject permanence requires working memory & inhibition – develops in children around 7 monthsDiamond & Goldman-Rakic(1989) – animals with lesionsto parietal lobes passed Anot B task; those with frontallesions did not
25 EF development and frontal lobe development Evidence suggests improvement in EF during childhood corresponds with growth spurts in frontal lobe developmentBell & Fox (1992) – EEG changes in frontal lobes during 1st year of life correlate with length of delay for response in delayed response tasksHowever, 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 childrenTherefore, note that limitations of case studies apply hereLack of consistent measures across casesAscertainment biases (bias in sampling – non-random)Nevertheless case studies produce fairly consistent findingsN.B. Very important to consider cases within developmental perspective
27 Children with acquired frontal damage – case studies Williams & Mateer (1992) DR- 8:11, falling beam- EEG & MRI showed damage to frontal region.Failure to maintain intellectual ability after injurySocial & language problems, but Verbal and non-verbal memory intactDifficulty with acquisition of new informationLittle spontaneous activityTantrums, 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 behaviourAge 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 3;11, lawn dartAge 5- good intellectual levels- good simultaneous but poor sequential processing- Verbal processing excellent, but needed instructions repeated extensivelyAge 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 effectsSuggests 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 effectsSome 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 SummaryEFs – multi-componential processes underlying flexible goal-directed behaviourEFs associated with PFCNumber of EF tasks/ but problematic – discriminant validityChild research gets around this to some extentCase studies suggest EFs similar in children and adults
33 ReferencesAnderson, 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,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,Cohen, J. D., & Servan-Schreiber, D. (1992). Context, cortex, and dopamine: A connectionist approach to behavior & biology in schizophrenia. Psychological Review, 99, 45-77Diamond, A., & Doar, B. (1989). The performance of human infants on a measure of frontal cortical development: The delayed response task. Developmental Psychology, 22,Diamond, A., & Goldman-Rakic, P. (1989). Comparison of human infants and rhesus monkeys on Piaget’s AB task: Evidence for dependence of dorsolateral prefrontal cortex. Experimental Brain Research, 74,Duncan, J., Burgess, P., & Emslie, H. (1995). Fluid intelligence after frontal lobe lesions. Neuropsychologia, 33,
34 ReferencesGlosser, G., & Goodglass, H. (1990). Disorders in executive control functions among aphasic and other brain-damaged patients. Journal of Clinical and Experimental Neuropsychology, 12,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,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,Marlowe, W. B. (1992). The impact of a right prefrontal lesion on the developing brain. Brain and Cognition, 20,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,
35 ReferencesSmith, 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,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,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,Williams, D., & Mateer, C. A. (1992). Developmental impact of frontal lobe injury in middle childhood. Brain and Cognition, 20,
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