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NYU / OTHER / PSYCHUA 25 / What do we think about a stimulus?

What do we think about a stimulus?

What do we think about a stimulus?

Description

School: New York University
Department: OTHER
Course: Cognitive Neuroscience
Professor: Lila davachi
Term: Spring 2017
Tags: brain, cognition, Cognitive Psychology, amygdala, emotion, learning, reward, and dopamine
Cost: 50
Name: Cog Neuro Exam 3 Study Guide
Description: Emotion & social cognition, reward, decision-making, amygdala, dopamine, learning, etc.
Uploaded: 04/26/2017
30 Pages 219 Views 7 Unlocks
Reviews


EMOTION & AFFECT, the amygdala and the ventro-medial Pre-frontal Cortex


What do we think about a stimulus?



Affective Neuroscience: the study of the neurobiology of emotions

● cognition and emotion are separate but also work together

● Some core emotional operations: perception and the production of emotions, decision-making, memory, & other cognitive processes

● Differences in emotional processing . . .

○ Basis of personality, social attitudes, vulnerability to psychopathology ● Universal human emotions-- Paul Ekman (1973)

○ Happiness, fear, anger, disgust, sadness, surprise (6 core emotions, more or less) ○ These emotions are biologically pre-progammed?

○ Categorical approach, probably not super accurate … a more continuous/ integrative approach is the Dimensions of Emotion:


What is an emotion?



● Measures of Emotion

○ Direct:

■ Manipulation of emotional state & ask self-report

■ Recognition of facial expression

○ Indirect:

■ Arousal of autonomic nervous system -- Galvanic skin response (GSR or SCR)

■ Judgment & decision-making -- evaluate possible choices


What is the relation bw social cognition & emotion?



Don't forget about the age old question of What is convective heat loss?

■ Inhibition & facilitation of response-- emotional stroop task

● Emotion as a Construction Experiment (Stanley Schachter)

○ What do we think about a stimulus? -- aka our appraisal of events

○ Emotion can be modulated by our own interpretations

○ People came into the lab and were given a pill (an adrenaline pill or a placebo) ■ Half the group (informed group) was told they would feel some type of arousal

■ In the waiting room, there were confederates

● Euphoria situation:

● Anger situation: confederate asks S intrusive annoying questions

■ RESULTS:

● Ss that were informed that they would feel aroused from the pill

--they attributed their noticed physiological arousal to the situation We also discuss several other topics like From where do right of people come according to john locke?

instead of the pill

● In the anger situation, those who were informed didn’t get angry at the annoying confederate bc they attributed their anger to the pill

● → if you use physiological arousal as the only measure of emotion, you’re leaving out the attribution of arousal to environment, etc.

which is really important!

● → it’s not just about a stimulus or the environment or another

person, it’s about a mix of all of it

● Misattribution of Emotion Experiment (Dutton & Aron, 1974)

○ Attractive female experimenter did some kind of cognitive study on a sturdy bridge or a rickety scary bridge

○ Results: More of the male Ss called the experimenter back when they met her on the scary bridge. They misattribute their arousal/fear/nervousness of being on the bridge to arousal based on the attractive experimenter. Don't forget about the age old question of What are the three factors that drive motivation?
If you want to learn more check out What is andrew jackson best known for?

○ Emotions can be attributed to the wrong source. If you want to learn more check out What is the humanistic approach in psychology?

What is an emotion?

● Stimuli and responses don’t happen in the same pathways

● stimuli→ attention→ appraisal→ response → stimuli

Smiling with Pencil Experiment (Facial Feedback Theory): ​If you produce a behavior (smiling) that is linked with an emotion (happiness) in a situation that isn’t necessarily happy . . .more Ss will report that in the smiling condition they felt happier!

→ can you take away that feedback? Botox Experiment We also discuss several other topics like What are the isms in art?

● Results: post-procedure, botox-injected Ss reported less emotion in response to pleasant & unpleasant films after procedure.

2 Brain Regions of Emotion

● Phineas Gage​- rod went thru his head and he lived → damaged a lot of his orbitofrontal cortex

○ Post-accident: Gage’s personality really changed- was emotional, frequent outbursts of anger, rage, couldn’t inhibit inappropriate behavior

● Frontal Lobotomies

○ The story of Agnes post-surgery:

■ No outward signs of emotion, no facial expression, no feelings towards other ppl, felt empty, zombie-like, lose prosody in language

○ These were done for ppl who had hallucinations, schizo, aggressive, angry, not controllable, etc.

● Orbitofrontal cortex has been linked with social & emotional decision-making ○ Patients often mimic the action of others & show utilization behavior--use a stimulus in sight even when inappropriate

○ Patients can describe their actions but show emotional detachment from consequences -- Antisocial, often can’t inhibit anger, violent

○ Some patients are flat in response to emotional stimuli, unlike regular controls: ■ Orbitofrontal patients show barely any skin conductance response

(measures sweat, indicator of arousal) to disturbing stimuli

Iowa Gambling Task: Patients don’t show the emotional sweating response and not making great decisions

Is it the lack of the SCR that leads to the poor decision-making? Or is it the other way around?

The Amygdala

● Processes emotional significance of stimuli

● Located in front of hippocampus

● Damage to amygdala→ difficulty recognizing facial emotions, reduced fear, impaired conditioned fear response

● In fMRI studies, the amygdala is activated by emotional (especially scary) stimuli, even if Ss are not aware of them.

● Conditioned fear response: Animals w lesions to amygdala don’t show anticipatory SCR to shocks, but show normal fear response to actual shocks

● Amygdala’s role in emotional learning: deficit in fear conditioning following amygdala damage but intact conscious knowledge of the association bw CS and US ○ Demonstrates role in explicit emotional learning

○ This woman w damage knows that shock is coming but doesn’t sweat- she just accepts it

● Fear Conditioning​: direct & indirect

○ The amygdala is crucial for the acquisition and expression of fear conditioning ○ Humans can learn the aversive properties of an event thru direct experience, but they can also learn thru obvservation

○ This is important bc learning about stimuli that should be feared thru social means is more efficient and has less costs.

● Amygdala and explicit memory

○ Amygdala modulates the strength of explicit memory for emotional events-- explicit memory can be formed despite amygdala lesions (i.e. hippocampus) but amygdala allows better recall over long-term for emotional events.

○ Events that are emotional are better remembered than neutral events//arousing events are maintained in LTM much longer than neutral events.

■ Amygdala may modulate LTP

■ Amygdala damaged patients don’t show this advantage for arousing

events

Guest Lecturer: What is the relation bw Social Cognition & Emotion​?

● Social cognition: what do you feel, think, want rn? What are your traits/dispositions? ● Emotion: what are you expressing and feeling? How can you control your emotions? ○ Much of our emotional life arises in social contexts

○ Social (perception & cognition) tasks often involve emotion

○ Social cognition and emotion depend on common (& distinct) processes and neural systems

Socioemotional Processing Stream

1. Learn affective value/ acquire response

a. Amygdala & nucleus accumbens ​crucial here

i. Amygdala tells you when there’s something relevant or survival-important info in your environment -- fear/danger

ii. → amygdala really responds to someone else’s fearful face bc that means there’s a potential threat in the environment

b. Nucleus accumbens responds to:

i. senses opportunity for desirable outcomes, unexpected rewards,

anticipation of rewards

ii. Responds to faces of attractive ppl, things you wanna buy

c. Medial PFC, OFC ​responds to:

i. Rewards received

ii. Valence of outcomes

iii. Updating reward values & expectations

iv. ACC & medial PFC respond to like/dislike judgments

2. → recognize affective value, initiate response

a. The Insula ​(in your brain) is critical bc it receives info about your body -- ex. Do you have cold feet, are you sweating, are you in pain, do you have butterflies in your stomach

i. The emotion of disgust​ really relates to the insula

ii. If you have lesions to the insula, you’ll have problems w recognizing disgust and realizing when others are disgusted as well.

b. The amygdala​ does not require attention/ conscious awareness to recognize fear etc

i. Enhanced arousal by anxiety, depression

ii. Amygdala also involved in feelings of hunger & other arousing stimuli iii. Amygdala responds to faces of untrustworthy people

3. → common systems from direct experience & social perception

a. Direct experience- self + Observation of other person- other = vicarious experience of what it’s like to be you

i. Inferior parietal lobule + premotor cortex --executing an action & seeing someone else execute action

ii. Mid-cingulate cortex + insula-- experiencing pain & seeing someone else experiencing pain

4. → draw high level inference about social/emotional stimuli

a. Ex. Why is this person crying? Why is he smiling?

b. The face, taken out of context, actually provides less info than body language! c. Context effects​ determine mapping bw internal state & facial expression! d. We have abstract social schemas/templates, emotional knowledge to perceive aggression, draw inferences, what’s normative behavior, etc

e. TPJ, superior temporal sulcus (STS), temporal pole, medial PFC, posterior cingulate/precuneus

f. Medial PFC​ is larger in humans than animals!

5. → regulate responses in context-appropriate manner / regulate emotion a. Stimuli in context → attention → appraisal → response → repeat

b. Associative learning: updates relationships bw stimulus/responses and outcomes -- update info/perceptions of ppl

c. Ventro-medial PFC​ is really important to update beliefs about threat value or reward value of stimuli

i. Ventro-medial PFC was what was damaged in Phineus Gage

REWARDS

● Can be primary (food, sex) or secondary (money)

● The brain uses rewards to learn, choose and prepare/execute goals.

● A pleasurable event that follows a specific behavior

● Function of awards

○ Elicit approach behavior (either thru innate mechanisms or learning)

○ Increase the frequency and intensity of a behavior that leads to a reward (learning)... drug addiction

○ Induce subjective feelings of pleasure (hedonia) and positive emotional states Dopamine (da)!

● Very important in reward learning

● Da is released during basic drives (hunger, sex)

○ Da is released in the rat Nacc right before and during copulation, but not after ○ Da is released in the human when presented w food

○ Released in both Nacc and caudate when playing video games for $

● PET Scans: measure binding to receptors in the brain

● Substantia nigra projects Da to striatum

● Not only important for modulating learning in the striatum but also the cortex ● Motor control, reward & value

○ Da is really important for motor learning (ex. A baby learning how to roll over) ○ Motor learning is modulated by a neuronal response binding to Da in the striatum ● Learning when you’ll get a reward is all about Da

○ If you predict a reward and don’t get it→ Da decreases

○ Earliest predictor of reward signals Da response instead of only fully predicted rewards

○ Da response= reward occurred - reward predicted

Decision-Making

● Often driven by our instincts, desires, habits

● Habitual learning also depends on striatum

Parkinson’s patients fMRI studies

● Healthy participants over time can get about 80% correct. Parkinson’s patients, before being put on Da medication, do not learn. But once they’re taking these drugs they perform just as well as healthy controls.

Motivation

● Motivation improves learning

○ Being in a motivated state, even before any reward, can enhance your attention & ability to learn

● But there are qualitatively different ways to motivate ppl to learn

● Seeking reward vs. avoiding punishment

○ Participants learned better in seeking reward condition in water maze experiment, performed worse in condition where they were avoiding the shock

● Can they influence performance differently?

● Reward can also influence what we remember

○ When you reward ppl for an item (animals vs. tools), they remember the animals better at a recognition test

○ Also better memory for items in pre-reward phase (retroactive effects of award) ○ → your brain can reach back in time and enhance memory for things related to reward.

■ These effects take time to emerge (it’s not immediate feedback learning like the baby learning to roll over)-- aka they require consolidation / 24

hours

Decision-Making & the Parietal Cortex’s Role

What influences decisions? Reward, emotion, context

● Sensory processing→ decision to act → motor output

Historical Roots of Decision-Making

● Descartes & Dualism: thought some decisions were based on sensory responses to environment

○ Brain & mind as 2 separate things

● Sherrington (1947): your reflex is a motor output as a result of sensory input Neurons of the monkey’s LIP are likely to respond to: the exertion of attention, but NOT to the existence of a visual stimulus screen.

Decision Factors

Decision-related activity in sensory cortex (MT) during motion discrimination ● ● 0% coherence- no sensory/stimulus info to tell you anything, but you have an output-- the animal will look one way or another.

● The animals are fixating, then 2 targets come on (right & left), then there’s a motion stimulus with varying coherence, then delay, then trained eye movement

○ motion stimulus gives animal evidence for which way the arrows are moving. ● There’s a relationship bw firign rate of MT neurons in a certain direction (coherence) and how well the animal did on the task

○ With very little info (10% coherence) the animal still got about 80% correct ○ Of all the neurons that are coding for preferred direction (MT neuron preferred direction), they are high-responding neurons → gives animal population of firing for a certain direction

○ Higher coherence of motion stimulus → better behavioral performance of animal ■ Firing of MT neurons is so highly correlated with behavior of animal ○ ○ Is MT output driving animal’s behavior ?? that’s what this result suggested. Integrative Post-Sensory Processing

● Integrators should show gradual increase in activity during motion stimulus if that eye movement or ‘choice’ is ultimately made

○ Integration happens over time, so neurons should show a gradual increase in activity, if the motor movement is going to be made. If the movement isn’t going to be made, neuronal activity should decrease.

● Rate of increase in activity should be a function of sensory signal (motion coherence): higher coherence → faster rate of rise

○ Animals are faster at 100% coherence than at 10% coherence.

● If a decision is made-- even in the absence of a true signal (0% coherence)-- activity in the integrator should still reflect the upcoming choice.

Parietal Cortex​: the parietal lobe is an area that connects visual input to eye movements. Neurons here have spatially selective response fields.

Integrative Post-Sensory Processing in LIP

So what happens if they eye movement has to reflect a more complex decision? ● Learned associations helps animals make decisions on where to move (to green or red

circle, for example--animal got juice if they looked to red circle for reward) ● Different elements predict the outcome w different probability -- the decision requires accumulation of evidence over time

Performance on Indirect Measures of Race Evaluation Predicts Amygdala Activation

Social Cognition & Attitudes

● Explicit attitudes/preferences differ from our implicit biases. Influenced by social context, culture, image management

● But behavior can be influenced by our ‘real/implicit’ attitudes ( a jury making a decision about afro-american vs. white person)

IAT (Implicit Association Test): tests the strength of association bw concepts ● Faster reaction times= stronger association

Big Picture: understanding the nature of our attitudes towards groups

● Mechanisms underlying indirect evaluations

● Is the amygdala involved in implicit bias towards afro-americans?

What do we already know?

● Amygdala is critical for: emotion learning & memory; evaluation of emotional stimuli & people

● Amygdala is often implicated in unconscious, subliminal, or pre-attentive stimuli ● So is the amygdala involved in evaluation of social or racial groups? Specifically in implicit/unaware biases?

White participants, shown pictures of white and black faces, had their amygdala response measured by fMRI.

● fMRI measure: white & black non-familiar/famous (exp.1) or famous (exp.2) neutral faces in a block design.

○ Correlated amygdala activity w explicit/implicit evaluations

● Behavioral measure:

○ implicit measure: Race IAT & Eyeblink Startle Response

■ IAT: categorize black/white faces + good/bad words

■ Startle response: more aversive stimulus→ more startle response

○ Explicit measure: Modern Racism Scale

■ A questionnaire that measures explicit conscious responses

EXPERIMENT 1 

Exp. 1 IAT Results:People take longer to respond in condition where black is paired with good and white is paired with bad.

Exp. 1 Eyeblink Results: more startle response to black faces

This sample of participants were not qualified at all as racist based on modern racism scale, but still showed the bias on implicit measures.

In both implicit measures, amygdala activity is positively directly correlated with bias. We don’t see this correlation in the explicit MRS measure.

→ Amygdala activity is correlated w implicit but not explicit measures of attitude. This aligns with their hypothesis.

Effects were somewhat specific to the amygdala, but the ACC and insula also activated (during implicit measures)

EXPERIMENT 2: famous, positively regarded black or white faces

● Less IAT bias (but they didn’t report any statistical test of the difference) ● No startle effect

● Like exp.1, No explicit bias (MRS): pro-black attitudes

● Implicit: no correlation bw amygdala activation & indirect or direct measures of racial bias

→ activity in the amygdala is correlated w implicit bias. Maybe this bias can be reduced when faces are familiar. Or, biases are learned (i.e. familiarity)

Limitations

● No main effect, correlations on limited # of participants

● Activation data didn’t include ALL trials. Don’t know why

Implications

● Amygdala response to black vs. white faces is a function of culturally acquired info about social groups, modified by individual knowledge & experience

● Amygdala may mediate unconscious learning & expression of negative social biases. ● Better understanding of the mechanisms may lead to better solutions and reducing biases. ● What do we need to do to change behavior?

EMOTION & AFFECT, the amygdala and the ventro-medial Pre-frontal Cortex

Affective Neuroscience: the study of the neurobiology of emotions

● cognition and emotion are separate but also work together

● Some core emotional operations: perception and the production of emotions, decision-making, memory, & other cognitive processes

● Differences in emotional processing . . .

○ Basis of personality, social attitudes, vulnerability to psychopathology ● Universal human emotions-- Paul Ekman (1973)

○ Happiness, fear, anger, disgust, sadness, surprise (6 core emotions, more or less) ○ These emotions are biologically pre-progammed?

○ Categorical approach, probably not super accurate … a more continuous/ integrative approach is the Dimensions of Emotion:

● Measures of Emotion

○ Direct:

■ Manipulation of emotional state & ask self-report

■ Recognition of facial expression

○ Indirect:

■ Arousal of autonomic nervous system -- Galvanic skin response (GSR or SCR)

■ Judgment & decision-making -- evaluate possible choices

■ Inhibition & facilitation of response-- emotional stroop task

● Emotion as a Construction Experiment (Stanley Schachter)

○ What do we think about a stimulus? -- aka our appraisal of events

○ Emotion can be modulated by our own interpretations

○ People came into the lab and were given a pill (an adrenaline pill or a placebo) ■ Half the group (informed group) was told they would feel some type of arousal

■ In the waiting room, there were confederates

● Euphoria situation:

● Anger situation: confederate asks S intrusive annoying questions

■ RESULTS:

● Ss that were informed that they would feel aroused from the pill

--they attributed their noticed physiological arousal to the situation

instead of the pill

● In the anger situation, those who were informed didn’t get angry at the annoying confederate bc they attributed their anger to the pill

● → if you use physiological arousal as the only measure of emotion, you’re leaving out the attribution of arousal to environment, etc.

which is really important!

● → it’s not just about a stimulus or the environment or another

person, it’s about a mix of all of it

● Misattribution of Emotion Experiment (Dutton & Aron, 1974)

○ Attractive female experimenter did some kind of cognitive study on a sturdy bridge or a rickety scary bridge

○ Results: More of the male Ss called the experimenter back when they met her on the scary bridge. They misattribute their arousal/fear/nervousness of being on the bridge to arousal based on the attractive experimenter.

○ Emotions can be attributed to the wrong source.

What is an emotion?

● Stimuli and responses don’t happen in the same pathways

● stimuli→ attention→ appraisal→ response → stimuli

Smiling with Pencil Experiment (Facial Feedback Theory): ​If you produce a behavior (smiling) that is linked with an emotion (happiness) in a situation that isn’t necessarily happy . . .more Ss will report that in the smiling condition they felt happier!

→ can you take away that feedback? Botox Experiment

● Results: post-procedure, botox-injected Ss reported less emotion in response to pleasant & unpleasant films after procedure.

2 Brain Regions of Emotion

● Phineas Gage​- rod went thru his head and he lived → damaged a lot of his orbitofrontal cortex

○ Post-accident: Gage’s personality really changed- was emotional, frequent outbursts of anger, rage, couldn’t inhibit inappropriate behavior

● Frontal Lobotomies

○ The story of Agnes post-surgery:

■ No outward signs of emotion, no facial expression, no feelings towards other ppl, felt empty, zombie-like, lose prosody in language

○ These were done for ppl who had hallucinations, schizo, aggressive, angry, not controllable, etc.

● Orbitofrontal cortex has been linked with social & emotional decision-making ○ Patients often mimic the action of others & show utilization behavior--use a stimulus in sight even when inappropriate

○ Patients can describe their actions but show emotional detachment from consequences -- Antisocial, often can’t inhibit anger, violent

○ Some patients are flat in response to emotional stimuli, unlike regular controls: ■ Orbitofrontal patients show barely any skin conductance response

(measures sweat, indicator of arousal) to disturbing stimuli

Iowa Gambling Task: Patients don’t show the emotional sweating response and not making great decisions

Is it the lack of the SCR that leads to the poor decision-making? Or is it the other way around?

The Amygdala

● Processes emotional significance of stimuli

● Located in front of hippocampus

● Damage to amygdala→ difficulty recognizing facial emotions, reduced fear, impaired conditioned fear response

● In fMRI studies, the amygdala is activated by emotional (especially scary) stimuli, even if Ss are not aware of them.

● Conditioned fear response: Animals w lesions to amygdala don’t show anticipatory SCR to shocks, but show normal fear response to actual shocks

● Amygdala’s role in emotional learning: deficit in fear conditioning following amygdala damage but intact conscious knowledge of the association bw CS and US ○ Demonstrates role in explicit emotional learning

○ This woman w damage knows that shock is coming but doesn’t sweat- she just accepts it

● Fear Conditioning​: direct & indirect

○ The amygdala is crucial for the acquisition and expression of fear conditioning ○ Humans can learn the aversive properties of an event thru direct experience, but they can also learn thru obvservation

○ This is important bc learning about stimuli that should be feared thru social means is more efficient and has less costs.

● Amygdala and explicit memory

○ Amygdala modulates the strength of explicit memory for emotional events-- explicit memory can be formed despite amygdala lesions (i.e. hippocampus) but amygdala allows better recall over long-term for emotional events.

○ Events that are emotional are better remembered than neutral events//arousing events are maintained in LTM much longer than neutral events.

■ Amygdala may modulate LTP

■ Amygdala damaged patients don’t show this advantage for arousing

events

Guest Lecturer: What is the relation bw Social Cognition & Emotion​?

● Social cognition: what do you feel, think, want rn? What are your traits/dispositions? ● Emotion: what are you expressing and feeling? How can you control your emotions? ○ Much of our emotional life arises in social contexts

○ Social (perception & cognition) tasks often involve emotion

○ Social cognition and emotion depend on common (& distinct) processes and neural systems

Socioemotional Processing Stream

1. Learn affective value/ acquire response

a. Amygdala & nucleus accumbens ​crucial here

i. Amygdala tells you when there’s something relevant or survival-important info in your environment -- fear/danger

ii. → amygdala really responds to someone else’s fearful face bc that means there’s a potential threat in the environment

b. Nucleus accumbens responds to:

i. senses opportunity for desirable outcomes, unexpected rewards,

anticipation of rewards

ii. Responds to faces of attractive ppl, things you wanna buy

c. Medial PFC, OFC ​responds to:

i. Rewards received

ii. Valence of outcomes

iii. Updating reward values & expectations

iv. ACC & medial PFC respond to like/dislike judgments

2. → recognize affective value, initiate response

a. The Insula ​(in your brain) is critical bc it receives info about your body -- ex. Do you have cold feet, are you sweating, are you in pain, do you have butterflies in your stomach

i. The emotion of disgust​ really relates to the insula

ii. If you have lesions to the insula, you’ll have problems w recognizing disgust and realizing when others are disgusted as well.

b. The amygdala​ does not require attention/ conscious awareness to recognize fear etc

i. Enhanced arousal by anxiety, depression

ii. Amygdala also involved in feelings of hunger & other arousing stimuli iii. Amygdala responds to faces of untrustworthy people

3. → common systems from direct experience & social perception

a. Direct experience- self + Observation of other person- other = vicarious experience of what it’s like to be you

i. Inferior parietal lobule + premotor cortex --executing an action & seeing someone else execute action

ii. Mid-cingulate cortex + insula-- experiencing pain & seeing someone else experiencing pain

4. → draw high level inference about social/emotional stimuli

a. Ex. Why is this person crying? Why is he smiling?

b. The face, taken out of context, actually provides less info than body language! c. Context effects​ determine mapping bw internal state & facial expression! d. We have abstract social schemas/templates, emotional knowledge to perceive aggression, draw inferences, what’s normative behavior, etc

e. TPJ, superior temporal sulcus (STS), temporal pole, medial PFC, posterior cingulate/precuneus

f. Medial PFC​ is larger in humans than animals!

5. → regulate responses in context-appropriate manner / regulate emotion a. Stimuli in context → attention → appraisal → response → repeat

b. Associative learning: updates relationships bw stimulus/responses and outcomes -- update info/perceptions of ppl

c. Ventro-medial PFC​ is really important to update beliefs about threat value or reward value of stimuli

i. Ventro-medial PFC was what was damaged in Phineus Gage

REWARDS

● Can be primary (food, sex) or secondary (money)

● The brain uses rewards to learn, choose and prepare/execute goals.

● A pleasurable event that follows a specific behavior

● Function of awards

○ Elicit approach behavior (either thru innate mechanisms or learning)

○ Increase the frequency and intensity of a behavior that leads to a reward (learning)... drug addiction

○ Induce subjective feelings of pleasure (hedonia) and positive emotional states Dopamine (da)!

● Very important in reward learning

● Da is released during basic drives (hunger, sex)

○ Da is released in the rat Nacc right before and during copulation, but not after ○ Da is released in the human when presented w food

○ Released in both Nacc and caudate when playing video games for $

● PET Scans: measure binding to receptors in the brain

● Substantia nigra projects Da to striatum

● Not only important for modulating learning in the striatum but also the cortex ● Motor control, reward & value

○ Da is really important for motor learning (ex. A baby learning how to roll over) ○ Motor learning is modulated by a neuronal response binding to Da in the striatum ● Learning when you’ll get a reward is all about Da

○ If you predict a reward and don’t get it→ Da decreases

○ Earliest predictor of reward signals Da response instead of only fully predicted rewards

○ Da response= reward occurred - reward predicted

Decision-Making

● Often driven by our instincts, desires, habits

● Habitual learning also depends on striatum

Parkinson’s patients fMRI studies

● Healthy participants over time can get about 80% correct. Parkinson’s patients, before being put on Da medication, do not learn. But once they’re taking these drugs they perform just as well as healthy controls.

Motivation

● Motivation improves learning

○ Being in a motivated state, even before any reward, can enhance your attention & ability to learn

● But there are qualitatively different ways to motivate ppl to learn

● Seeking reward vs. avoiding punishment

○ Participants learned better in seeking reward condition in water maze experiment, performed worse in condition where they were avoiding the shock

● Can they influence performance differently?

● Reward can also influence what we remember

○ When you reward ppl for an item (animals vs. tools), they remember the animals better at a recognition test

○ Also better memory for items in pre-reward phase (retroactive effects of award) ○ → your brain can reach back in time and enhance memory for things related to reward.

■ These effects take time to emerge (it’s not immediate feedback learning like the baby learning to roll over)-- aka they require consolidation / 24

hours

Decision-Making & the Parietal Cortex’s Role

What influences decisions? Reward, emotion, context

● Sensory processing→ decision to act → motor output

Historical Roots of Decision-Making

● Descartes & Dualism: thought some decisions were based on sensory responses to environment

○ Brain & mind as 2 separate things

● Sherrington (1947): your reflex is a motor output as a result of sensory input Neurons of the monkey’s LIP are likely to respond to: the exertion of attention, but NOT to the existence of a visual stimulus screen.

Decision Factors

Decision-related activity in sensory cortex (MT) during motion discrimination ● ● 0% coherence- no sensory/stimulus info to tell you anything, but you have an output-- the animal will look one way or another.

● The animals are fixating, then 2 targets come on (right & left), then there’s a motion stimulus with varying coherence, then delay, then trained eye movement

○ motion stimulus gives animal evidence for which way the arrows are moving. ● There’s a relationship bw firign rate of MT neurons in a certain direction (coherence) and how well the animal did on the task

○ With very little info (10% coherence) the animal still got about 80% correct ○ Of all the neurons that are coding for preferred direction (MT neuron preferred direction), they are high-responding neurons → gives animal population of firing for a certain direction

○ Higher coherence of motion stimulus → better behavioral performance of animal ■ Firing of MT neurons is so highly correlated with behavior of animal ○ ○ Is MT output driving animal’s behavior ?? that’s what this result suggested. Integrative Post-Sensory Processing

● Integrators should show gradual increase in activity during motion stimulus if that eye movement or ‘choice’ is ultimately made

○ Integration happens over time, so neurons should show a gradual increase in activity, if the motor movement is going to be made. If the movement isn’t going to be made, neuronal activity should decrease.

● Rate of increase in activity should be a function of sensory signal (motion coherence): higher coherence → faster rate of rise

○ Animals are faster at 100% coherence than at 10% coherence.

● If a decision is made-- even in the absence of a true signal (0% coherence)-- activity in the integrator should still reflect the upcoming choice.

Parietal Cortex​: the parietal lobe is an area that connects visual input to eye movements. Neurons here have spatially selective response fields.

Integrative Post-Sensory Processing in LIP

So what happens if they eye movement has to reflect a more complex decision? ● Learned associations helps animals make decisions on where to move (to green or red

circle, for example--animal got juice if they looked to red circle for reward) ● Different elements predict the outcome w different probability -- the decision requires accumulation of evidence over time

Performance on Indirect Measures of Race Evaluation Predicts Amygdala Activation

Social Cognition & Attitudes

● Explicit attitudes/preferences differ from our implicit biases. Influenced by social context, culture, image management

● But behavior can be influenced by our ‘real/implicit’ attitudes ( a jury making a decision about afro-american vs. white person)

IAT (Implicit Association Test): tests the strength of association bw concepts ● Faster reaction times= stronger association

Big Picture: understanding the nature of our attitudes towards groups

● Mechanisms underlying indirect evaluations

● Is the amygdala involved in implicit bias towards afro-americans?

What do we already know?

● Amygdala is critical for: emotion learning & memory; evaluation of emotional stimuli & people

● Amygdala is often implicated in unconscious, subliminal, or pre-attentive stimuli ● So is the amygdala involved in evaluation of social or racial groups? Specifically in implicit/unaware biases?

White participants, shown pictures of white and black faces, had their amygdala response measured by fMRI.

● fMRI measure: white & black non-familiar/famous (exp.1) or famous (exp.2) neutral faces in a block design.

○ Correlated amygdala activity w explicit/implicit evaluations

● Behavioral measure:

○ implicit measure: Race IAT & Eyeblink Startle Response

■ IAT: categorize black/white faces + good/bad words

■ Startle response: more aversive stimulus→ more startle response

○ Explicit measure: Modern Racism Scale

■ A questionnaire that measures explicit conscious responses

EXPERIMENT 1 

Exp. 1 IAT Results:People take longer to respond in condition where black is paired with good and white is paired with bad.

Exp. 1 Eyeblink Results: more startle response to black faces

This sample of participants were not qualified at all as racist based on modern racism scale, but still showed the bias on implicit measures.

In both implicit measures, amygdala activity is positively directly correlated with bias. We don’t see this correlation in the explicit MRS measure.

→ Amygdala activity is correlated w implicit but not explicit measures of attitude. This aligns with their hypothesis.

Effects were somewhat specific to the amygdala, but the ACC and insula also activated (during implicit measures)

EXPERIMENT 2: famous, positively regarded black or white faces

● Less IAT bias (but they didn’t report any statistical test of the difference) ● No startle effect

● Like exp.1, No explicit bias (MRS): pro-black attitudes

● Implicit: no correlation bw amygdala activation & indirect or direct measures of racial bias

→ activity in the amygdala is correlated w implicit bias. Maybe this bias can be reduced when faces are familiar. Or, biases are learned (i.e. familiarity)

Limitations

● No main effect, correlations on limited # of participants

● Activation data didn’t include ALL trials. Don’t know why

Implications

● Amygdala response to black vs. white faces is a function of culturally acquired info about social groups, modified by individual knowledge & experience

● Amygdala may mediate unconscious learning & expression of negative social biases. ● Better understanding of the mechanisms may lead to better solutions and reducing biases. ● What do we need to do to change behavior?

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