1 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 powder in order to level the terrain Once forgot to put in sand… What did change? What did we 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 was removed by the tamping rod was responsible for the restraint and well-mannered behavior that most people possess, and that Gage lost in the accident.
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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
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