Week 9: Executive Functions Flashcards
what is executive function?
cognitive control
- ability to plan and control our behaviour
- Ability to ignore irrelevant behaviour and perform task correctly (inhibition)
- Set of psychological processes that enable us to use our perception, knowledge and goals to bias the selection of actions and thoughts from multiple possibilities
Who was phineas gage?
- explosive accident with tamping iron in PFC
- Pre-accident: hard-working, energetic, clear thinker
- Post-accident: aggressive, impulsive, unable to follow plans
What is a prefrontal lobotomy?
- by Antonio Egas Moniz
- Used for Schizophrenia and Depression
- Results: sedation-like / happiness effect with no negative side effects on general performance (as believed)
- > 80.000 cases
- Occasionally even still in use today (method of last resort)
- Prefrontal = „silent lobe“?
What do „Stability“ and „Flexibility“ mean in the context of executive functions?
Stability = ability to shield your action plans against competing demands
→ less stability → distractibility
Flexibility = ability to disengage from action plans that are not useful anymore
→ less flexibility → perservation
What are the two different definitions of the PFC?
Definition 1: functional
→ Based on movement
→ regions of the frontal lobe that do not elicit movement when stimulated
Definition 2: anatomical
→ projection zone of mediodorsal thalamic nucleus
What converges in the PFC?
- PFC as area of information convergences from:
- Motor structures
- Inferior temporal cortex
- Medial temporal structures
- Auditory cortex
- Posterior parietal cortex
How can the PFC be subdivided?
- lateral PFC (executive functions, task-relevant information, working memory, goal representation)
- Ventromedial PFC
- Premotor areas
- Primary Motor areas
- anterior PFC (complex action plans, working memory, decision making)
- Posterior cingulate gyrus
- Anterior cingulate gyrus (conflict, errors)
- Broca‘s area (language)
- Orbitofrontal Cortex (reward)
How does the size of PFC differ between humans in animals
- relative size of PFC in human is higher than in mammals below great apes
- Relative human PFC size matches that of other great apes
what is unique about the development of the PFC?
in humans PFC obtains peak cortical thickness later than other regions
What are consequences of prefrontal cortical lesions?
- Disinhibition (loss of cognitive control) (stroop task)
- slowing of thoughts
- Loss of spontaneity
- Task Switching (loss of cognitive flexibility)/ Preservation errors (card sorting example)
- Deficiencies in foresight and planning (tower of London task)
- Tendency to confabulate
- Loss of self-awareness and flat affect (especially empathy)
How are action plans made in the brain?
- lPFC and parietal cortex seems to be where sensory stimuli is transformed into an action plan
→ transducer sensory information into actions that are in accordance with action plan
Norman & Shallice model
- central executive model
- If it‘s a routine situation, the convention scheduling is active → „autopilot“
- PFC becomes involved when you detect a conflict in your environment and you don’t have a prepared action plan for it → novel, non-routine situation → supervisory attentional system active
Miller & Cohen
- Shows bias signals from PFC
- PFC allows us to have flexible stimulus-response mappings (not hardwired)
- Example: telephone ringing at home versus a friends house
- If SR was hardwired you would pick up the phone
- A bias signal shifts you to not pick up the phone because of the context (shift from transmissive to modulators mode)
- Problem: cannot explain endogenous behaviours
what is the stroop interference task ?
- Reading words versus naming colors
- Reading out loud is overreached response
- Slower RT in incongruent trials → overriding overlearned response makes us respond slower
- Cognitive control is implemented by biasing relevant associations
What is ERN?
- error-related negativity
- Negative EEG signal around ACC
- More active in response to incongruent than congruent stimuli
- Amount of conflict in trial
- Measured conflict is used to enhance amount of control in follow up trials
what is the stability - plasticity dilemma?
Ability to Learn new knowledge (plasticity) comes at expense of ability to remember past knowledge (stability) and vice versa
What is the role of the ACC in the context of executive functions?
- error/ conflict detection
- Alarm system: break out of routine
