PSY605: Executive Control

• Source-Site Model
• Posner and Peterson
• Frontal-parietal control tells what attention should be doing at temporal, occipital, etc.

• Higher order cogntive operations that are subserved by the prefrontal cortex
• Programming, regulating, monitoring, attention/inhibition, task management, contextual coding, planning
• Ability to plan for a goal, be flexible, prioritize tasks, switch between tasks, evaluate efficacy

• Schemata: Fully automatic processing (knowledge)
• Contention Scheduling: Passive processing controlled (action sequence)
• Supervisory Attentional System: Overriding action sequence

• Automatic organization of schemata together
• Without conscious awareness
• When routines clash, relative importance is used to determine which to perform

• Lateral Prefrontal Cortex
• Ventromedial Prefrontal Cortex

MFG, SFG, IFG

Damage in the middle/superior/inferior frontal gyrus (MFG, SFG, IGF)

• Strengths - Robust activator of executive functioning
• Weaknesses - Doesn't distinguish types of executive functioning or inform how they are organized in the brain

• Task: Sorting a deck of cards into groups
• Condition A - Task , no distractions
• Condition B - Task while hearing and counting sounds of various pitches

• Hippocampal Activity - greater for A
• Striatal Activity - greater for A

Formation of long-term memories and motor functioning better for A!

• Task Switching
• Novely Detection
• Initiation/Cessation of Action
• Inhibition
• Self-Monitoring
• Sequencing
• Abstract Thinking

Perform two tasks (i.e. report the letter if the card is green, and the number if it is red)

Switch Cost = (RT on Switch from last card) - (RT on No-Switch from last card)

• Switch - Longer for normal subjects
• Takes even longer for PFL patients

• Oddball task (press button for gray circles (targets))
• P3b - Parietal lobe - appears for response to targets
• P3a - Frontal lobe - exhibited for task-irrelevant, rare (novel) items - doesn't show up for PFL patients

• Psychological inertia: Difficult to initiate an action and difficult stopping it (perservation)
• Perservation: Tendency to repeatedly perform the same behavioral response even when no longer appropriate

Seen in Wisconsin Card Sorting

• Behavior is driven by environmental cues
• Can't help but engage in schemas (can't override it)

• Tied with inferior frontal cortex
• Go/No-Go Task -- either respond or withhold response

• Evaluation of the appropriateness of one's actions and plans
• Error-Related Negativity

• Tapping into brain-basis of self-monitoring, and hence indexes it
• But may index an emotional, not just a cognitive, reaction
• 100-150ms after a response
• Tied to person thinking they made an error
• Greater when accuracy is emphasized (as opposed to speed)
• Greater the larger the error
• Dipole Modeling - ERN generated in the Anterior Cingulate Cortex

• A very specific process that may be damaged with frontal damage
• Damage patients - poor at determining which item appeared more recently
• Difficulties even when patient determines the order

Behaviour of frontal patients reflects the functioning of contention scheduling in the absence of supervisory attention