lecture 10: emotion 1 Flashcards
What is EMOTION?
A discrete affective response indicating the salience/value of an internal or external event comprised of:
– Klaus Scherer: “interrelated, synchronized changes in the states of all or most of the five subsystems in response to the evaluation of an external or internal stimulus event as relevant to major concerns os the
organism”
– Joseph LeDoux: Subjective Feelings
parasympathetic system (rest and digest)
The parasympathetic nervous system predominates in quiet conditions while the sympathetic nervous system drives the “fight or flight” response in stressful situations. The main purpose of the PNS is to conserve energy to be used later and to regulate bodily functions like digestion and urination
sympathetic system (fight or flight)
Your sympathetic nervous system is best known for its role in responding to dangerous or stressful situations. In these situations, your sympathetic nervous system activates to speed up your heart rate, deliver more blood to areas of your body that need more oxygen or other responses to help your get out of danger
CRF
Cortocotropin
releasing factor released by the thalamus
Corticotropin-releasing hormone (CRH; previously known as corticotropin-releasing factor) is the central regulator of the hypothalamic-pituitary-adrenal (HPA) axis, which is the main organizer of the body’s response to stress.
ACTH
Adrenocorticotropic hormone (ACTH) is a tropic hormone produced by the anterior pituitary. The hypothalamic-pituitary axis controls it. ACTH regulates cortisol and androgen production. Diseases associated with ACTH include Addison disease, Cushing syndrome, and Cushing disease
Mood
Diffuse affect state, characterized by a
predominance of subjective feelings that affect the experience and behavior of the person. May be longlasting, and not event focus
an emotion can trigger a mood, which is longer lasting
Affect Dispositions
Stable personality traits and dispositions that have an affect core. The tendency of a
person to experience certain moods (anxious, jealous).
Can also describe psychopathologies
Social Emotions
Love, Guilt
Parsing emotional experience
A widely accepted theory of basic emotions and their expressions, developed Paul Ekman, suggests we have six basic emotions. They include sadness, happiness, fear, anger, surprise and disgust
Cross cultural affect labels
– around 35 (Scherer, Keltner)
There are a few primary dimensions to emotional
experience:
Valence (good-bad) and Arousal (how
intense).
Three Theories of Emotion:
The interaction between subjective experience and physiological state
james-lange theory
cannon bard theory
schachter singer two factor theory
james-lange theory
The James-Lange theory of emotion suggests that physical changes in the body happen first, which then leads to the experience of emotion. Essentially, emotions stem from your interpretation of your physical sensations. For example, your heart beating wildly would lead you to realize that you are afraid
problem: Another criticism of the James-Lange theory is that physical reactions don’t have a single corresponding emotion. For instance, heart palpitations could suggest fear, excitement, or even anger. The emotions are different, but the physical response is the same.
cannon bard theory
The Cannon-Bard theory of emotion states that stimulating events trigger feelings and physical reactions that occur at the same time. For example, seeing a snake might prompt both the feeling of fear (an emotional response) and a racing heartbeat (a physical reaction).
problem: One of the predominant criticisms of the Cannon-Bard theory is that it assumes that physical reactions don’t influence emotions. However, a large body of research on facial expressions and emotion suggests otherwise.
schachter singer two factor theory
Schachter and Singer’s (1962) Two-Factor Theory of Emotion suggests that physiological arousal determines the strength of the emotion, while cognitive appraisal identifies the emotion label. So, in this theory, the “two-factor” represents physiological change and cognitive appraisal change.
For example, if you were to see a venomous snake in your backyard, the Schachter–Singer theory argues that the snake would elicit sympathetic nervous system activation (physiological arousal) that would be cognitively labeled as fear (cognition) based on the context.
problem: However there are many weakness of the method used by Schachter and Singer. The experiment definitely lacked ecological validity. We do not usually experience emotions in the way in which Schachter and Singer induced them.
Neural Systems of Emotional Processing
Early concept: The Limbic System
Papez (1932) proposed a circuit of neural structures involved in emotional processing including: hypothalamus, anterior thalamus, cingulate gyrus and hippocampus
- Maclean (1949), inspired by demonstrations of Kluver-Bucy Syndrome, named these structures “Papez Circuit” and extended the network of emotion to include the amygdala, orbitofrontal cortex and portions of basal ganglia. This
extended system was called the “limbic system”
Kluver-Bucy Syndrome:
Bilateral Damage to Medial Temporal lobe
Kluver-Bucy syndrome (KBS) is a rare neuropsychiatric disorder due to lesions affecting bilateral temporal lobes, especially the hippocampus and amygdala. It is characterized by hyperorality, hypermetamorphosis, hypersexuality, bulimia, placidity, visual agnosia, and amnesia
*Problems with limbic system concept:
Unclear why some structures are “limbic” and not others, what is the criteria for a
limbic structure?
– Some limbic regions originally thought to be primarily involved in emotion are now
known to be more important for non-emotional, cognitive behaviors (e.g.,
hippocampus)
– No evidence these regions represent a ‘system’ or ‘circuit’ of emotion
– Because of these issues, some have suggested abandoning the ‘limbic’ system concept
– Terms “limbic system” or “limbic” regions are still used today, primarily because of inclusion of orbitofrontal cortex and amygdala
what part of the brain is involved in Acquiring fear/threat
amygdala
How do objects and people acquire emotional
significance?
what part of the brain is involved in Controlling fear/threat
amygdala and prefrontal
cortex
– How do we alter emotional significance?
Ivan Pavlov
In the study of digestion, Pavlov observed that the experimental dogs salivated when fed red meat. Before feeding a dog, Pavlov might set a metronome at, say, sixty beats a minute. The next time the dog heard a metronome at any speed, it would salivate. But when only that particular metronome setting was reinforced with food the dog became more discriminating
Classical conditioning theory states that behaviors are learned by connecting a neutral stimulus with a positive one, such as Pavlov’s dogs hearing a bell (neutral) and expecting food (positive). The learned behavior is called a conditioned response
Pavlov’s famous experiment of the drooling dog shows that there are two types of reflexes: innate reflexes that are evoked by the irritant itself and acquired reflexes that are evoked by subsequent associations’
The Amygdala Fear/Threat Circuit
Sensory information converges in the lateral nucleus (LA - site of memory storage), which projects to the central nucleus (CE), which projects to the
brainstem/hypothalamus
The amygdala can respond to learned threats quickly, prior to full sensory
processing, via projections from the sensory thalamus (LGN, MGN)
amygdala
The amygdala participates in the regulation of autonomic and endocrine functions, decision-making and adaptations of instinctive and motivational behaviors to changes in the environment through implicit associative learning, changes in short- and long-term synaptic plasticity, and activation of the fight-or-flight response
Like other animals, the human amygdala is necessary
for the physical expression of a learned
aversive response in fear conditioning
Threat Conditioning in Humans
- This simple model of threat learning applies to the social communication of threat
- Cognitive (language) and social
(observation) means of threat learning takes
advantage of phylogentically older
mechanisms of fear conditioning
Germs
the social communication of fear/threat
Mechanisms of Threat/Fear Control
Two techniques currently used clinically
extinction
cognitive emotion regulation
Extinction
– Forms the basis for exposure therapy
Amygdala BOLD Decreases During Extinction
vmPFC BOLD Increases During Extinction
Exposure therapy is a type of therapy in which you’re gradually exposed to the things, situations and activities you fear. There are a few different approaches to this therapy. It can help treat several conditions, like phobias, post-traumatic stress disorder (PTSD) and panic disorder
- Cognitive Emotion Regulation
– Forms the basis for cognitive therapy
Cognitive behaviour therapy (CBT) is a type of psychotherapy. It may help you to change unhelpful or unhealthy ways of thinking, feeling and behaving. CBT uses practical self-help strategies. These are designed to immediately improve your quality of life. CBT can be an effective way to treat depression and anxiety.
what part of the brain is necessary
for the learning and retrieval of
extinction
The ventral medial prefrontal
cortex (VMPFC)
amygdala
plays a role in the acquisition of extinction
flashbulb memory
A flashbulb memory is an accurate and exceptionally vivid long-lasting memory for the circumstances surrounding learning about a dramatic event. Flashbulb Memories are memories that are affected by our emotional state
The Amygdala Fear/Threat Circuit
The Prefrontal Cortex inhibits the expression of the threat memory to allow the expression of the safe (extinction) memory and the cognitive regulation of
threat memories
explain relapse following extinction
Following extinction and emotion regulation
threat/fear reactions are susceptible to relapse under stress, passage of time, context shifts and other reexposure to the US
This is reflected clinically in the relapse rate following
exposure and/or cognitive therapy
* Can we enhance the persistent control of threat using novel techniques?
– Reconsolidation
explain a study of reconsolidation
Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition
Studies in rats block the reconsolidation of memory (and erase the fear) by injecting protein synthesis inhibitors into the amygdala during the
reconsolidation window
not safe in humans
targeting reconsolidation May prevent the relapse of threat responses by reducing
dependence on prefrontal inhibitory mechanisms, but successful clinical translation may be difficult
How do scientists think about emotion?
- Basic emotions (as seen through facial expression)
- Dimensions of emotion (as reactions to events)
Basic emotions
People all of the world show pretty much the same facial
expressions for 6 basic emotions:
High agreement for anger, happiness, disgust, surprise, sadness,
and fear
Basic emotions: Ekman’s “Universal Facial Expressions”
Anger, happiness, disgust, surprise, sadness, fear
- Basic emotions
(as seen through facial expression)
- Dimensions of emotion
(as reactions to events)
Emotions tap into a “core affect” system and are
CONSTRUCTED as reactions to events along continuous
dimensions
* Example:
VALENCE (negative – positive)
vs.
AROUSAL (low – high)
Fear conditioning:
A form of classical conditioning in which
a neutral stimulus (e.g., light) acquires aversive properties by
virtue of being paired with an aversive event (e.g., shock)
However, lesions to amygdala do
prevent learning of the conditioned
startle response (e.g., won’t startle from
light alone)
* Impaired conditioned fear
Amygdala
Your amygdala is a small part of your brain, but it has a big job. It’s a major processing center for emotions. It also links your emotions to many other brain abilities, especially memories, learning and your senses. When it doesn’t work as it should, it can cause or contribute to disruptive feelings and symptoms
Amygdala is connected to many other parts of cortex
(sensory cortex, MTL, etc.)
Inputs from multiple brain regions converge on the
lateral nucleus (LN) of the amygdala
Conditioned Fear in Humans
Conditioned with a blue square (conditioned stimulus) and a
mild electric shock (unconditioned stimulus)
* Dependent measure: Skin conductance response (SCR)
Skin conductance response (SCR)
- Place electrodes on fingers
- Hook up to measuring device
- Measures autonomic arousal
the conductance is measured by placing two electrodes next to the skin and passing a tiny electric charge between the two points. When the subject increases in arousal, his/her skin immediately becomes a slightly better conductor of electricity because they sweat
Unlike the epidermis and dermis layers of our skin — which are poor conductors of electricity — our sweat is rich with electrolytes such as sodium and chloride, which makes our sweat a surprisingly decent conductor of electricity (though not quite as good as metal)
Healthy subjects show an increase in SCR when they experience something
emotionally arousing (can be pleasant or unpleasant)
Case Study: Patient S.P.
- Bilateral amygdala damage
- Although normal subjects show increased SCR after
conditioned fear, Patient S.P. does NOT show increased SCR to
conditioned stimulus (i.e., no emotional learning) – impaired
implicit learning
Patient S.P.’s explicit learning is intact à she explicitly
learns that blue square = shock, even though no SCR
response
Attention selection over time: The
attentional blink paradigm
If a second item is right after the first, it is often
missed. If it is presented later, participants catch it.
Demonstrates attention selection over time
The increase in detection for ‘early’ words is evidence for
improved attention during emotional processing
- Emotional arousal improves perception
- The amygdala influences perception to ease/improve processing
Emotion and encoding: visual
perception enhancement
Cue attention with a face in one location. The face is either fearful
or neutral
* Task: detect specific gabor patches in that location
* If the face is fearful, participants are able to detect fainter patches.
* If fearful faces all over (no relationship to where the gabor appears), there is no benefit to attention.
* Take home point: emotion enhances perception
- Emotion enhances perception and perceptual benefit of attention
Emotion and retention: patient evidence
- Study a series of taboo and
neutral words - Asked to recall the words after
a delay - Controls did not forget as
many taboo words as neutral
words - Amygdala patients show no
such benefit of emotional
words on consolidation
Fear conditioning: Amygdala circuit
ln to cn to brainstem/hypothalamus
- There are multiple sensory pathways to the amygdala:
- “Slow road” or “High road”: sensory stimuli are relayed through the
thalamus to the cortex where they are processed before information
is relayed to the amygdala
- “Slow road” or “High road”: sensory stimuli are relayed through the
- “Fast road” or “Low road”: sensory stimuli are directly relayed from
thalamus to the amygdala
- “Fast road” or “Low road”: sensory stimuli are directly relayed from
