Frontal Lobe Functions - Courses.ucsd.educourses.ucsd.edu/frose/ps125/Lectures/NP_5b_Frontal...1...
Transcript of Frontal Lobe Functions - Courses.ucsd.educourses.ucsd.edu/frose/ps125/Lectures/NP_5b_Frontal...1...
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Frontal Lobe Functions
Fredric E. Rose, Ph.D.Winter 2006
Pivotal Case:Phineas Gage
9/13/1848 25 yo construction foreman for Rutland
and Burlington RR in New England Used a tamping iron to fill holes in
stones with sand over explosive powderin order to level the terrain
Once forgot to put in sand…
What did change? What didwe learn from this?
Pre-accident personality Responsible, intelligent, honest, well-liked by peers
and elders, “the most efficient and capable man”according to employers
Post-accident personality Disinhibited, irreverent, capricious, disrespectful of
social conventions, unable to hold a job Equipotentiality v. Localization of Function
Harlow (1868): some portion of the brain that wasremoved by the tamping rod was responsible for therestraint and well-mannered behavior that mostpeople possess, and that Gage lost in the accident.
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Gage Revisited (Science,1994) Damasio & Damasio Computer graphics to plot
trajectory Ventromedial OFC region,
sparing of Broca’s and otherFL motor regions
Region is responsible fordecision-making regardingpersonal and socialmatters,as well as emotionprocessing
Anatomy of the Frontal Lobes
3 prefrontal regions:DorsolateralOrbitofrontalMesial
Frontal Lobe Circuitry
Oculomotor Motor Dorsolateral Orbitofrontal Anterior Cingulate
Alexander, DeLong, & Strick (1986). Parallelorganization of functionally segregated circuitslinking basal ganglia and cortex. Annual Review ofNeuroscience, 9, 357-381.
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Neurotransmitters Glutamate (corticostriatal, thalamocortical) GABA (basal ganglia) Dopamine (cortical, subcortical)
Modulates all 3 circuits Acetylcholine (striatal)
Open circuit influence) Serotonin (cortical, subcortical)
Core Frontal Circuitry
Thalamus
Subthalamic
Internal External
Striatum
Frontal Cortex
Globus Pallidus
Glutamate (+)Glutamate (+)
Glutamate (+)
GABA (-)
GABA (-)
GABA (-)
Feifel (1999)
Dorsolateral Circuit Functions
Subserves executive function Behavioral responses to complex
problems Activation of remote memories Environmental independence Shifting/maintaining cognitive sets Generating motor programs Verbal mediation of behavior
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Executive Functions
Planning
Decision making
Self-directed goal selection
Monitoring, guiding, and directing behaviorto achieve a goal
Dorsolateral CircuitDysfunction
Poor organizational behavior Poor memory search strategies Environmental dependency Poor set shifting
(perseveration) Verbal/manual dissociations
Orbitofrontal Circuit Functions
2 parallel circuits: Lateral and Medial Personality Characteristics
Empathy Civility Social appropriateness
Environmental independence Emotional continence
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Orbitofrontal CircuitDysfunction
Personality Changes Tactlessness Impulsivity Irritability Antisocial behavior
Utilization/imitation behavior Mood disorders Obsessive-Compulsive disorder
Orbitofrontal Syndrome
Emotional lability (mood swings) Disinhibition Criminal behavior Unusual/impulsive sexual behavior Often lack awareness Anosmia Environmental Dependency Pseudopsychopathic
Anterior Cingulate Functions
Motivated Behavior Drive Spontaneity “Personhood” Creativity
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Anterior CingulateDysfunction
Akinetic mutism Indifference to pain Apathy Poverty of speech Psychic emptiness Excessive conformity Poor response inhibition
Personality Changes
Impairments in social skills inappropriate or bizarre social behavior “loosening" of normal social restraints
Change in motivation apathy, withdrawal, lack of interest, and
initiative Pseudodepression / pseudoretarded
Summary of Personality/BehavioralSymptoms
POSITIVE Disinhibition Impulsivity Vulgarity Irritability Emotional lability Inappropriate
laughter, crying Bizarre behavior
NEGATIVE Apathy Reduced initiative
(Abulia) Reduced interest in
daily activities/self-care
Akinetic mutism Social withdrawal
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Personality/BehavioralAssessment
Observation Impulsive, disinhibited, environmentally
dependent… Questionnaires
Self-report Caregiver/family member
Interviews Patient Family
Secondary Motor Cortex
Supplementary Motor Area Sequencing, timing, and proper initiation
of voluntary movements. PET studies
Specific vs random motor sequence magining this movement.
Injury – disorder of motor planning,organization, and initiation
Premotor Area Sequencing, timing, and proper initiation of
voluntary movements. BUT… more in external cue readiness,
such as the interval between CUE and GO. Cingulate Motor Area
Emotional or motivational impetus formovement (when reward is involved)
Injury – lack of spontaneous motor activity,reduced speech output
Secondary Motor Cortex (cont.)
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Measures of SMC Functioning
Written Alternating Sequences
Perseveration: the inability to stopbehaviors once they have started
•Motor Impersistence: a form of distractibility in whichpatients only briefly sustain a motor action in response to acommand such as "Raise your arms" or "Look to the right."
Measures of SMC Functioning(cont.)
Luria 3-Step Fist, Edge, Palm
Go-No Go (also Orbital-PFC –disinhibition)
Multiple Loops
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Apraxia Inability to execute purposeful, complex
motor acts, despite physical ability,comprehension, and willingness.
Ideomotor Apraxia: Gestures tocommand
Motor representations in Parietal Lobe,but Premotor Cortex (including SMA)translates into movements
Frontal Release Signs
FL lesions (nonlocalized; dementia)can produce a return of primitivereflexes: Grasp Sucking/”Snout” Groping Utilization behavior
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Summary of Motor Symptoms ofFL Disorder
Poor motor sequencing Poor initiation of movements Dysarthria Apraxia Frontal release signs
Assessing ExecutiveFunctions
Anatomy of the Frontal Lobes
3 prefrontal regions:DorsolateralOrbitofrontalMesial
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Divide these 6 stimuli into 2 groupsbased on a shared characteristic.
Now do it again based on anothershared characteristic.
Stroop Color-Word Test
RedRedRedGreen
GreenBlueGreenRed
BlueGreenBlueGreen
RedBlueRedBlue
BlueRedGreenGreen
GreenBlueRedBlue
RedGreenBlueRed
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
XXXXXXXXXXXX
Stroop Color-Word Test
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Stroop Color-Word Test
RedRedRedGreen
GreenBlueGreenRed
BlueGreenBlueGreen
RedBlueRedBlue
BlueRedGreenGreen
GreenBlueRedBlue
RedGreenBlueRed
Wisconsin Card Sorting Test
Deck of cards with differentstimuli on each
Patient sorts the deck into 4piles according to “key”cards
Told only if right or wrong oneach sort
Letter Fluency
60
45
30
15
0
SecLipsF*ck!Cat
FlowerCabbageFiddleCrayonFeverFudgeCaterpillar
LemonFudgeCatchingListFeverCatchFudgeLeverCar
LFC
SPEED FACTORS-poor initiation-poor maintenance
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Trail Making Test A
E
B
D
G
H
A
CF
Trail Making Test B
1
2
B
4
C
3
AD
Rey-Osterrieth Complex Figure
copy
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So, what are“Executive Functions”?
Generate a list and identify the theme.
Planning Organizing Selective attention Problem-solving Initiating Inhibiting Self-monitoring Abstract thinking Mental flexibility
Executive functions are complex functions that allow one to engage in effective and efficientgoal-directed behavior.
What’s the common thread?
FL Memory Functions
Working MemoryRetrieval
Source Memory
Working Memory
Serial 7’s Put this in order with letters first, then numbers:
“L-4-C-2-M-8”. Spell “WORLD” backwards. What does these have in common? Define
‘working memory.’ What are the 2 maincomponents? an active system for temporarily storing and
manipulating information needed in the execution ofcomplex cognitive tasks
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Working Memory (pp. 169-170)
Baddeley (1986): WM has 3 components Central executive Articulatory phonological loop Visual-spatial sketch pad
Goldman-Rakic (1988) Dorsolateral prefrontal cortex holds
information “on line” while it is processed(monkey research).
Confirmed by PET and fMRI
Paced Auditory Serial AdditionTask (PASAT)
4382378
“7”
“11”
“10”
“5”
“10”
“15”
EXAMINER PATIENT
TIME Phonological Loop
orVisual-spatial Sketchpad
N-back
1-Backtarget
2-Backtarget
0-Backtarget
Cn
AN
Xc
Time
Phonological Loopor
Visual-spatial Sketchpad
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Spatial Span Task
Phonological Loopor
Visual-spatial Sketchpad