Neuropsychological Functions of the prefrontal cortex

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Neuropsychological Functions of the prefrontal
cortex

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Overview

• Prefrontal executive function
• Regional prefrontal syndromes
• Neuropsychological assessment of prefrontal
  syndromes

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The prefrontal lobe as the seat of the highest
human mentality

• Phylogenetic perspective
• Ontogenetic perspective
• Anatomical perspective
• Neuropsychological perspective

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Phylogenetic perspective Species differences in
prefrontal cortex
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Ontogenetic perspectiveLate maturation of
prefrontal cortex
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Anatomical perspective Extensive prefrontal
lobe connections
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Neuropsychological perspectivePhineas Gage
(accident in 1848)
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Prefrontal function Early descriptions

• Personality (Harlow, 1868)
• Abstract attitude (Goldstein, 1927)
• Mental set (Jacobsen, 1935)
• Self-regulation (Luria, 1962)
• Concept formation (Milner, 1964)

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Prefrontal function Recent descriptions

• Supervisory mental process
• Cognitive flexibility
• Meta-cognition
• Goal-directed behavior
• Executive function

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An example of an executive
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A model of prefrontal executive function
Memory
Executive Function
Language
Spatial Pr
Attention
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The regional prefrontal syndromes(Cummings, 1985)
Dorsolateral
Orbitofrontal
Mesial frontal
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Core hypotheses
Anatomical area Function Syndrometype
Dorsolateral Cognition Disorganized
Orbitofrontal Emotion Disinhibited
Mesial frontal Motivation Apathetic
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Dorsolateral syndrome(Disorganized type)

• Poor judgment
• Concrete thinking
• Lack of insight
• Poor planning
• cognitive inflexibility

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Orbitofrontal syndrome (Disinhibited type)

• Social misbehavior
• Poor impulse control
• Emotional lability
• Hypersexuality
• Stimulus-driven behavior

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Mesial frontal syndrome (Apathetic type)

• Poor initiative
• Diminished verbal output motor behavior
• Akinetic mutism
• Urinary incontinence

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Neuropsychological assessment of prefrontal
syndromes Overview

• WAIS Poor sensitivity
• MMPI Poor response validity
• Specialized tests are needed
• EXIT (EXecutive Intelligence Test)
• (Kim, 2001)

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EXIT (EXecutive Intelligence Test)

• Norm 1619, 2024, 2534, 3544, 4554,
  5564 yrs
• Adm time 25 minutes
• Score EIQ (Executive IQ)
• Subtests Stroop test
• Verbal fluency Design fluency
• Rey AVLT

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Stroop test
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Verbal fluency
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Design fluency
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Rey AVLT

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Core features of EXIT as a psychometric
instrument

• Multi-task approach
• Unstructured testing
• Use of control tests
• Qualitative scoring
• Normative M100, SD15

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The rationale for prefrontal pathology in
schizophrenia

• Disorganized thinking, speech, behavior
• Disordered dopamine systems
• Prefrontal metabolic deficit

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A validity study of EXIT

• Sample Schizophrenic pts n45
• Normal controls n27
• Measure WAIS VIQ, PIQ, FIQ
• EXIT EIQ
• Hypothesis Largest group-difference in EIQ

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Schizophrenic pts vs Normal controls
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Case 1 Frontal head injury

• Male, 29 yrs
• Policeman
• Car accident 6 months ago
• Personality deteriorationDisorganized
  behavior

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Case 2 Parkinsons disease

• Female, 63 yrs
• Housewife
• Parkinson-like symptom onset 3.5 yrs ago
• Progressive deterioration

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Case 3 Korsakoffs disease

• Female, 39 yrs
• Housewife
• Heavy alcohol ingestion during last 4 yrs
• Physical weaknessMental confusion

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Case 4 Carbon monoxide poisoning

• Male, 36 yrs
• Unemployed
• Heart attack 6 months ago
• RestlessnessStimulus-driven behavior

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Summary

• Prefrontal lobe as the central executive
• 3 types of regional prefrontal syndromes
• EXIT (EXecutive Intelligence Test)