Cognitive Control PDF

Cognitive Control Chapter 12 1 The Problem of the Homunculus Who’s in Charge of your Mind? 2 1  Cognitive Control Topics l Frontal Lobe Structures l Hierarchical Model of Lateral PFC l...

Cognitive Control Chapter 12 1 The Problem of the Homunculus Who’s in Charge of your Mind? 2 1  Cognitive Control Topics l Frontal Lobe Structures l Hierarchical Model of Lateral PFC l Task-Switching – Rule-Switching l Planning l Working Memory l Cognitive Inhibition of Behaviors l Decision-Making 3 Domain-Specific & Domain-General l Domain-Specific Processing l Specialized processing limited to a specific type of information l Processing tends to be very fast, often with little conscious awareness l Evolutionary Mind Modules l Domain-General Processing l General Purpose processing l Processing tends to be slow and attentionally demanding Cognitive Control functions are largely domain-general 4 2  Major brain regions that support executive control Pre-Frontal Cortex – dl,vl,dm,vm Orbito-Frontal Cortex Anterior Cingulate Posterior Parietal Cortex Caudate & Putamen = dorsal striatum (parts of cerebellum, too) 5 Mammalian Neocortex l Human neocortex has 1000 times the surface area of mouse neocortex, but only twice the thickness l White Matter expansion is also substantial, especially in humans relative to other primates 6 3  Expansion of Prefrontal Cortex 7 Comparative anatomy of the prefrontal cortex Great Apes actually similar in proportional size of PFC 8 4  Frontal Lobe Subdivisions l Prefrontal Cortex – l Portion of Frontal Lobe in front of Motor & Pre-motor Cortex l SMA, PMC, Broca’s are not considered prefrontal l Lateral Prefrontal l Dorsal & Ventral l Frontal Pole l Medial Frontal l Includes Anterior Cingulate l Ventromedial prefrontal l Orbitofrontal 9 Parceling the Brain based on connectivity Cognitive Control Network is Orange N=1000 Lateral Prefrontal, dorsal anterior cingulate cortex, Lateral and medial posterior parietal, anterior insula, … 10 5  Basal ganglia control of behavior Different BG regions Participate in different Functions Anterior Caudate in Prefrontal Loop 11 Goal-directed behavior & Hierarchical planning Requires: Planning Task-switching Maintaining goals Monitoring Progress Making Decisions 12 6  Evidence for a Hierarchy of Cognitive Control Increasing Complexity from Posterior to Anterior in Lateral PFC Green (Ventral Pre-Motor): Stimulus-Response Mapping Yellow (Lateral PFC): Stimulus Context; Manipulation Red (Frontal Pole): Cognitive Context; Rules 13 Cognitive Control Topics l Frontal Lobe Structures l Hierarchical Model of Lateral PFC l Task-Switching – Rule-Switching l Planning l Working Memory l Cognitive Inhibition of Behaviors l Decision-Making 14 7  Rule Switching ‘Cognitive Set’ – the rules and key information held in working memory that support performance of a particular task 15 Wisconsin Card Sorting Task Test of Rule Learning & Task Switching l Match Cards based on one of 3 rules: l Color, Shape, Number l Not explicitly told which rule applies. l “correct” or “incorrect” lThe rule is changed without warning l Q: How fast can the subject switch rules l Lateral PFC patients perseverate (get stuck) Reveal Dysexecutive symptoms 16 8  Rule Switching in WCST Inferior Frontal Sulcus 17 Rule Switching in WCST Inferior Frontal Sulcus 18 9  Anterior Cingulate Cortex (ACC) ACC is on medial surface of frontal lobe 19 Stroop Effect Ant. Cingulate Cortex Word reading is “automatic” and can interfere (or aid) the color-naming task, which is more novel / less practiced 20 10  Stroop Effect Interactions between Medial and Lateral PFC ACC activity not ACC activity on just about conflict one trial – violated Predicts LPFC expectations activity on next trial 21 Error-Related Negativity (ERN) Hypothesized to originate in Anterior Cingulate Anterior Cingulate Responds with errors, But also is activated With other forms of Monitoring 22 11  Inhibitory Control of Action Right Inf. Prefrontal Ctx DTI tract-tracing: IFC connects with: Subthalamic nucleus of BG preSupplementary Motor Area Stop-Signal or ‘Go / No Go’ Task 23 How do we make decisions? l Decisions: l Choosing an Apartment & Roommate l Choosing a career l Ordering lunch l Buying shoes l What clothes to wear today l Key Neuroscience Issues l Assigning Value l Estimating Probability of Outcomes l Accumulating Evidence & Reaching a Decision 24 12  Rational Choice Theory (from Economics) l Assumes that people are: l Fully informed l Sensitive to subtle differences l Fully Rational l Implies that people: l Will always do what is in their best interest l People seek to maximize something l Expected Value 25 Assessing Value For one spin or for 100 spins? 26 13  Expected Value l Expected Value describes the average reward of a probabilistic process l Expected Value = Probability * Utility l Ex: 5% chance at $1000 or 20% chance at $300 l 5% chance of getting $1000, 95% chance of $0 l Expected Value = 0.05 * 1000 = $50 l 20% chance of getting $300 l Expected Value = 0.20 * 300 = $60 l Utility can be positive or negative l 40% chance of getting a $25 parking ticket l Expected value -$10 l Expected Value is the sum of the probability-utility pairings for each possible outcome 27 Daniel Kahneman Wins Nobel October 2002 "for having integrated insights from psychological research into economic science, especially concerning human judgment and decision- making under uncertainty" Prospect Theory 28 14  Dual System Model of Cognition l System 1: ‘Hot’ l Fast, parallel, automatic and context-dependent l Linked to Emotionally Guided Decisions l e.g., immediately available reward l “Limbic” circuitry – ventral striatum, OFC, vmPFC, l System 2: ‘Cool’ l Slow, serial, controlled and evidence-based l Linked to more rational & deliberate decision processes l “Executive Function” circuitry (latPFC, dACC, PPC) Also See Dan Kahneman’s “Thinking Fast & Slow” 29 The relation between objective and subjective value (or utility) l As the total amount increases, we are less sensitive to differences l General Law of Psychology known as the Weber-Fechner Law l Log Compression 30 15  Value-based Decisions: Ventro-medial prefrontal cortex & subjective value 31 Reward Circuitry & Dopaminergic pathways l Dopamine l Serves as reward signal l Key to how we value things l Dopamine neurons found l in Substantia Nigra (SN), Ventral Tegmental Area (VTA) l VTA plays key role in reward evaluation l Projection to Nucleus Key structures: VTA Ventral Striatum ~ Nucleus Accumbens Accumbens (NA), mPFC, Amygdala, Hippocampus 32 16  Midbrain dopaminergic neurons in response to expected and omitted rewards l Reward Prediction Error: l Dopamine Release increases when an VTA unexpected reward occurs Neurons l No change in Dopamine when reward matches expectations l Decrease in dopamine when reward is omitted Dopamine neurons do not code reward, per se. But rather code changes in information / value Supporting Learning of the changes 33 Reward prediction error (RPE) Key to Temporal Difference Learning Model Dopamine neurons in the ventral tegmental area (VTA) and substantia nigra (SNc) appear to mimic the error function (RPE) 34 17  Dual System Model of Cognition l System 1: ‘Hot’ l Fast, parallel, automatic and context-dependent l Linked to Emotionally Guided Decisions l e.g., immediately available reward l “Limbic” circuitry – ventral striatum, OFC, vmPFC, l System 2: ‘Cool’ l Slow, serial, controlled and evidence-based l Linked to more rational & deliberate decision processes l “Executive Function” circuitry (latPFC, dACC, PPC) Also See Dan Kahneman’s “Thinking Fast & Slow” 35 Dual Systems OFC / vmPFC Reflects value LPFC reflects Self-control 36 18  Delayed Gratification: The Marshmallow Expt 37 Temporal discounting Getting the same reward sooner has greater subjective value (and greater real value) 38 19  Temporal Discounting l Increased Valuation for Immediately available rewards l Reflected in activation of Ventral Striatum, Post. Cing Ctx & mPFC l Tracks Subjective Value of Rewards 39 OFC Damage Impairs Temporal Discounting 40 20  Marshmallow Experiment fMRI 40 Years Later! l Prefrontal cortex: l Differentiated between no-go and go trials to a greater extent in high delayers l Ventral striatum: l Exaggerated recruitment in low delayers. l Resistance to temptation (as measured originally by the delay-of-gratification task) is a relatively stable (trait) individual difference l Predicts reliable biases in frontostriatal circuitries that integrate motivational and control processes. 41 42 21  Everybody: Go-NoGo RH Inf. Frontal CTX: High Delayers Ventral Striatum: Low Delayers 43 Decision Making Summary l Dopamine system (esp, VTA, Ventral Striatum) provides a means for coding value l VTA / dopamine signals changes in info, not reward. Signal to support learning l Value-based decisions l Vent. Striatum codes motivation / value l vmPFC / Orbito-Frontal Cortex codes subjective value l Salience network (dACC, Ant Insula) & Executive Function (lat PFC, PPC) code more cognitive factors l Value-free decisions (e.g., did it move left or right) utilize integration mechanisms within executive function network (PFC, PPC) 44 22  Cognitive Control Summary l Frontal Lobe Structures l Hierarchical Model of Lateral PFC l Task-Switching l Planning l Working Memory l Cognitive Inhibition of Behaviors l Decision-Making 45 23