I owe it all to my prefrontal cortex!
The prefrontal cortex of the frontal lobe is where a lot of thinking goes on. Some regions are better understood than others. The three major sections are dorsolateral, orbitofrontal and ventral-medial. They work together with other regions to make decisions, regulate behavior and anticipate rewards.
This area of the brain is the most likely to get damaged, since it is furthest forward in the head. But it isn’t clear what the actual results will be. You can have a metal rod through your head and have minor difficulties or show no outward damage and have major dysfunction.
NOTES
- Pre-Frontal Cortex
- Phineas Gage
- First indication can survive major brain trauma
- Lost 1+ frontal lobe
- Working on a railroad in 1848
- Tapered rod thru back of left eye
- Out the top of his head
- Rod landed 80 feet away
- Retained
- Normal memory
- Speech & motor skills
- Changed?
- Mood, irritability, impatient
- Personality
- Impact exaggerated after his death
- “American Crowbar Case”
- Localization of functions
- His case was used pro and con
- Damage to frontal lobe
- Can describe best course of action
- But seek immediate gratification
- Phineas Gage
- Frontal lobes
- 1. Primary Motor cortex
- 2. Pre-motor cortex
- 3. Pre-frontal cortex
- Most anterior
- Not short term storage
- But if damaged, poor executive processes
- 3. Prefrontal cortex
- 10+ microscopically different cells
- working memory for objects
- working memory for spatial locations
- 3 regions
- a. dorsolateral
- b. orbitofrontal
- c. ventralmedial
- A. Dorsolateral
- last part of brain for myelination
- still developing at 30 years old
- interacts with other parts of brain
- Connected to
- Orbitofrontal prefrontal cortex
- Thalamus & Basal Ganglia
- Hippocampus
- Plus more
- Functions
- Location of stimuli
- Spatial info for sequence learning
- High-level planning & regulation
- Organizes movements
- Regulates thoughts & actions
- Integrates sensory & mnemonic info
- Executive Processes
- Not sole responsible
- Collaborative effort
- Damage causes problems with
- Social judgment
- Executive memory
- Abstract thinking
- Intentionality
- Tumors produce symptoms similar to schizophrenia
- Sleep deprivation inhibits activity here
- Truth Telling
- Involved in lying?
- Inhibit of normal process
- People usually tell the truth
- Lucid dream states?
- Hallucinations?
- B. Orbitofrontal
- Orbit – immediately above eye sockets
- Least explored
- Least understood
- Sometimes considered part of limbic system
- Controls
- social adjustment
- responsibility
- mood
- drive
- Function
- Cognitive processing
- Decision making
- Sensory integration
- Affective value of reinforcers
- Expectation of rewards-punish
- Compare expected with actual
- intuitive judgments
- Connections
- Extensive connections
- Reciprocal connections
- Ventral & dorsal visual streams
- Auditory-spatial processing
- Phonetic processing
- All sense modalities
- Damage
- Alzheimer’s disease
- neurofibrer tangles in this area
- Lesions
- feel no regret
- Causes problems with
- decision-making
- emotion regulation
- reward expectation
- Alzheimer’s disease
- ADHD
- dysfunction of reward circuitry
- controlling motivation
- reward
- impulsivity
- Obsessive-Compulsive
- Executive functioning
- Impulse control
- Addictions
- Dopaminergic activation of reward circuits
- Compulsive behavior
- Increased motivation take drug
- Decision making
- Reward system
- During cocaine withdrawal
- Increased metabolism in OFC
- Proportional to drug craving
- During protracted withdrawal
- (up to 3-4 months) cocaine
- reduced activity compared to healthy
- Alcoholics
- Less benzodiazepine receptors
- During withdrawal
- Decreased activity (compared to normals)
- Visual discrimination test
- Reversal learning
- Presented pictures A and B
- Learn rewarded for picking A
- When rule set, switch
- Damage to OFC, stay with A
- Extinction
- Rules don’t reversing
- Punished for either A or B
- DON’T PRESS BUTTON
- OFC damage: gotta press!
- Reversal learning
- Iowa Gambling Task
- 4 virtual decks of cards
- Each time choose a card win $$
- Every so often, will lose $$
- Win as much money as possible
- Choose by gut reaction
- Two decks are “bad decks”
- net loss in long run
- Two decks are “good decks”
- net gain over time
- Healthy Ss
- Sample each deck
- Stick to good after 40-50 cards
- OFC damage
- Stick with bad deck
- Even if know it’s a bad deck
- Galvanic Skin R of stress react
- Hover over bad deck
- Only 10 trials
- OFC dysfunction
- Never develop GSR reaction
- Faux pas Test
- Series of vignettes
- Social occasion
- Said but should not have said
- Awkward occurrence
- Identify what was said
- Why it was awkward
- How people would have felt
- OFC dysfunction
- Understand the story
- Can’t judge social awkward
- Disinhibited behavior
- Excessive swearing
- Hypersexuality
- Poor social interaction
- Compulsive gambling
- Drug, alcohol & tobacco use
- Little empathy
- Orbit – immediately above eye sockets
- C. Ventralmedial
- Includes
- Anterior cingulate cortex
- Hippocampus
- Includes
- 1. Anterior Cingulate Cortex
- Collar around corpus collosum
- Autonomic functions
- Heart rate & blood pressure
- Reward anticipation
- Decision making
- Empathy
- Dorsal part connects with
- Prefrontal cortex
- Parietal cortex
- M1
- Dorsal part as Central Station
- Processing top-down $
- Processing bottom-up $
- Assigning control to other areas
- Ventral part connects with
- Nucleus accumbens
- Hypothalamus
- Amygdala
- Ventral part involved in
- Assessing salience of emotion
- Assessing motivational info
- Problem solving
- When effort needed for task
- Activated by conflict
- Potential of an error
- Eriksen Flanker Task
- Arrow pointing to left or right
- Flanked by two distractor arrows
- compatible (<<<<<)
- incompatible (<<<>>)
- Stroop Task
- Don’t read word, name color
- Top-Down Processing
- Say the color you see:
- RED
- ORANGE
- GREEN
- BLUE
- Counting-Stroop
- Count neutral stimuli
- ‘dog’ presented four times
- Count interfering stimuli
- ‘three’ presented four times
- Count neutral stimuli
- Eriksen Flanker Task
- Functions
-
- Error detection
- Anticipation of tasks
- Attention, motivation
- Regulation of emotional R
- Error detection
- Respond to letter X after an A
- Ignore all other letter combos
- Monitoring conflict
- Incompatible trials produce the most conflict
- Conflict control system
- Reinforcement learning ERN
- Error-related negativity (ERN)
- Electrophysiological marker
- Making errors may cause changes in dopamine?
- More avoid errors, larger ERNs
- More learn from errors, less ERNs
- Receives conflicting input
- Assigns it to another area
- Reward-based learning theory
- detects and monitors errors
- evaluates degree of error
- suggests appropriate action
- Largest activation in loss
- Conscious experience corr
- more emotionally-aware
- recognition of emotional cues
- Active even when Ss not aware of their error
- Role in registering pain
- Physical pain activates ACC
- More intense pain, more active
-
- Damage causes
- Unclear what actually can’t do
- Appears to impact:
- Inability to detect errors
- Severe difficulty in Stroop task
- Emotional instability
- Inattention
- Maybe be seen in schizophrenia
- Social anxiety
- ADHD
- OCD
- Right Hemisphere
- Better at spatial relationships
- Better at perceiving patterns
- Better at perceiving emotions
- in gestures
- In tone of voice
- Damage
- Speak with less inflection
- Less expression in voice
- Left Hemisphere
- Better at details than patterns
- Lateralization of Function
- Best Practice
- Use same hemisphere for repeat measurements
- More accurate if smell two substances with same nostril
