PSYC 125: Executive/Frontal Lobe Functioning

phineas gage case

* railroad accident
* had seizures, became a jerk/didn’t follow social norms
* lived for 13 years
* could function and hold a job

phineas gage pre accident personality

responsible, intelligent, well-liked

phineas gage post accident personality

impulsive, inappropriate, disrespectful

equipotentiality

* everything is equal in the brain; if 1 area is damaged then another can make up for it
* discarded idea

localization of function

functions are completely localized and separate

what region is responsible for decision making and personal/social matters

ventromedial orbitofrontal cortex

how is the frontal lobe split

into 3 areas: motor area, premotor area, and prefrontal area

where is the motor area

top of frontal lobe

where is the premotor area

middle of frontal lobe

where is the prefrontal area

bottom of frontal lobe

what are the prefrontal regions

* dorsolateral
* orbitofrontal
* medial frontal/cingulate

important neurotransmitters

* glutamate
* GABA
* dopamine
* AcH
* serotonin

glutamate

* corticostriatal/thalamocortical
* cortex
* **excitatory**
* keeps brain active

GABA

* basal ganglia
* **inhibitory**
* low levels → anxiety
* xanax is gabaergic

dopamine

* cortical/subcortical
* involved in love
* modulates 3 circuits: reward, addiction, motivation

AcH

* striatal
* memory system
* peripheral NS (muscle contraction)

serotonin

cortical/subcortical

core frontal circuitry

* cortex sends excitatory glutamate to striatum → sends inhibitory GABA to globus pallidus and subthalamic


* there is a balance
* a lot of excitement in striatum = inhibition in GP & subthalamic

dorsolateral circuit known as

cognitive circuit

dorsolateral circuit features

* executive function
* monitoring behavioral responses to complex problems
* activates remote memories (storage & retrieval)
* not letting environment dictate behavior (not using toilet in home depot)
* shifting/maintaining goal
* generating motor programs
* verbal mediation of behavior

executive functions

* planning
* decision making
* self directed goal selection
* monitoring behavior to achieve goal

dorsolateral circuit dysfunction

* poor organizational behavior (doing things out of order)
* poor memory search strategies
* giving in to environment
* poor change approach
* verbal/manual dissociations (told not to do something but does it anyway)

oribitofrontal cortex known as

social and emotional cortex

the parallel circuits in orbitofrontal

lateral & medial

orbitofrontal circuit functions

* personality characteristics (empathy, civility, social appropriateness)
* environmental independence
* emotional control

orbitofrontal circuit dysfunction

* personality changes (impulsivity, irritability, antisocial)
* using objects when it’s not appropriate
* mood disorders
* OCD

orbitofrontal syndrome

* mood swings/problems controlling emotions
* disinhibition
* criminal behavior
* impulsive sexual behavior
* lack awareness
* anosmia (absence of smell b/c olfactory bulb under frontal lobes)
* environmental dependency
* behaviors similar to psychopath

anterior cingulate cortex known as

motivated behavior cortex

anterior cingulate function

* motivated behavior
* drive
* spontaneity
* personhood
* creativity

anterior cingulate dysfunction

* akinetic mutism (don’t speak)
* absence of spontaneous movement
* indifference to pain
* apathy (lack of enthusiasm)
* reduced speech
* feel empty
* problems w/ go-no go task

anterior cingulate cortex personality changes

* impairments in social skills
* inappropriate behavior
* loosening of normal social constraints
* change in motivation
* lack of interest
* looks depressed and loss of function

summary of anterior cingulate cortex personality/behavior symptoms

* positive: new increase in certain behaviors
* impulsivity
* irritability
* dishinhibition
* negative: loss of certain behaviors
* apathy
* reduced initiative
* reduced interest in daily activities

personality/behavioral assessments

* observation
* impulsive, disinhibited, environmentally dependent
* questionnaires
* self-report
* family member/caregiver
* interviews
* patient
* family

secondary motor cortex

* supplementary motor area
* premotor area
* cingulate motor area

cingulate motor area

* emotional movement (reward involved)
* injury: lack of spontaneous motor activity, reduced speech output

premotor area

* sequencing, timing, initiation of voluntary movements in **external** cues

supplementary motor area

* sequencing, timing, planning of voluntary movements
* **internal cues**
* injury: disorder of motor planning, organization, initiation

measures of SMC function

* written alternating sequences
* injury: can’t alternate sets

perseveration

inability to stop behaviors once they’ve started

motor impersistence

failure to continue behavior once initiated

apraxia

* inability to execute complex motor acts


* motor representations in parietal lobe, but premotor cortex (and SMA) translates into movements

frontal release signs

* FL lesions can produce primitive reflexes:
* grasp
* sucking/snout
* utilization behavior

summary of motor symptoms of FL disorder

* poor motor sequencing & movement initiation
* dysarthria (poor articulation)
* apraxia
* frontal release signs

california sorting test

* divide stimuli into groups based on shared characteristic & then do it again on another shared characteristic
* tests goal solving & coming up with a new way if old way is ineffective

stroop test

tests response suprression/ignoring distractions

wisconsin card sorting test

tests cognitive flexibility

letter fluency

tests search strategy

trail making test

connect dots in ABC order then in alternating order of numbers and letters

ray-osterrieth complex figure

tests how person approached problem