Observations on Frontal Lobe
Function
Restlessness – animals with bilateral frontal lobe
lesions move about consistently and aimlessly
Indifference – such animals show suppression of
curiosity and interest
Decreased affect – bifrontal animals show little
interest or concern toward other animals
Emotionality – these animals suffer a strong fear of
noise, other animals, stimuli which does not disturb
them in the natural habitat
Abnormal mental state – such animals show defective
reflection, judgment, memory, inability to adapt
Instincts – certain instincts have been weakened
Activity – tendency toward stereotypic and automatic
activities
Observations on Frontal Lobe
Function
Restlessness – animals with bilateral frontal lobe
lesions move about consistently and aimlessly
Indifference – such animals show suppression of
curiosity and interest
Decreased affect – bifrontal animals show little
interest or concern toward other animals
Emotionality – these animals suffer a strong fear of
noise, other animals, stimuli which does not disturb
them in the natural habitat
Abnormal mental state – such animals show defective
reflection, judgment, memory, inability to adapt
Instincts – certain instincts have been weakened
Activity – tendency toward stereotypic and automatic
activities
Bianchi (1895)
Anatomical Subdivisions of
Frontal Cortex
Frontal Subcortical Circuits
Circuits unite functional regions of the
frontal cortex with the basal ganglia
and thalamus in networks mediating
motor activity, eye movements, and
behavior.
Five circuits have been identified and
named according to their function or
cortical site of origin.
Frontal Lobes and Executive
Dysfunction
About 1/3 of cortex is contained in the frontal
lobes
Area of the brain that is most “developed” in
humans compared to other primates
Damage tends to affect cognitive/behavioral
functions typically regarded as uniquely
human
Damage to similar areas in different
individuals can produce strikingly different
impairment
The Frontal Lobes and Executive Dysfunction
Executive functions: Highest order cognitive functions
Capacity for autonomous behavior without external guidance
Directed behavior when goal is remote or absent
Self-direction, self-monitoring, self-regulation
Ability to organize a behavioral response to a novel or complex
situation / problem
Planning and regulation of adaptive and goal-directed behavior
Problem solving / reasoning / generating solutions to problems
Spontaneity and fluency of thought and action
Cognitive flexibility
Strategic use of memory
Ability to shift cognitive set
Ability to inhibit or withhold responses as appropriate
Ability to focus or sustain attention (inhibit attentional capture by
nonrelevant stimuli)
Two Broad Frontal Syndromes
1. Dorsolateral prefrontal syndrome
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Lowered general arrousal
Impaired attention/distractable
Apathy, depressed mood
Perseverative behavior
Working memory deficits
Diminished spontaneous behavior
Difficulty with goal-directed behavior
“Stimulus Boundedness”
Two Broad Frontal Syndromes
2. Ventromedial prefrontal syndrome
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Disinhibition of drives
Impulsivity
Elevated mood
Hyperactive
Impaired attention
Executive Dysfunction:
•Working memory deficits
•Temporal memory / Source memory
•Perseveration
•Loss of spontaneous behavior
•Apathy
•Planning deficits/impaired goal-directed behavior
•Disinhibition/impulsive behavior
•Impaired attention
•Depression
•Elevated mood
Executive Dysfunction
Associated with:
Frontal lobe brain damage (TBI, CHI, lesions, etc.)
Dementia
Major depression
Parkinson’s/Huntington’s disease
HIV-Related Dementia
Subcortical strokes
Schizophrenia
Alcoholic Dementia (Wernicke-Korsakoff syndrome)
Memory-related deficits
Working memory: delayed response tasks
Temporal memory: when did the event occur?
Source memory: where did I get this
information from?
Confabulation: production of fabricated
accounts of past events
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Momentary – plausible but incorrect memories
which fill the gap
Fantastic – unnecessary and implausible memories
(e.g., story is a wild concoction of past events)
Inhibition-Related Deficits
Perseveration
Inability to inhibit a dominant response
set
Social Disinhibition/Impulsivity
Loss of spontaneous behavior
Poor planning/goal-directed behavior?
Attentional deficits?
Mood/Affect/Emotion Symptoms
Depression
Mood elevation
Apathy/Indifference
Agitation
Disinhibition/Impulsivity
“Personality Change”
Phineous Gage
Railroad foreman
Well-respected, hard-working
1848: tamping iron accident
He never lost consciousness, and had
no obvious neurological symptoms
But he was “no longer Gage”
Phineous Gage
Gage’s Doctor described Gage’s post
accident personality as
Fitful, irreverent, indulging at times in the greatest
profanity which was not previously his custom,
manifesting but little deference for his fellows, impatient
of restraint and advice when it conflicts with his desires,
at times pertinaciously obstinate, yet capricious and
vacillating, devising many plans of future operation,
which are no sooner arranged than they are abandoned
… a child in his intellectual capacity and manifestations,
he has the animal passions of a strong man.