PS231 Lecture 28 - Emotions 2 (Neural Mechanisms & Fear)(1)
Page 1: Title and Subtitle
Title: Faradization and Camera
Author: Duchenne (1862)
Page 2: Announcements
Reading Assignment for Friday:
Textbook Chapter 15, Sections 15.4 & 15.5
Section 15.4: Neural Circuitry, Hormones, and Synaptic Transmitters Mediate Violence and Aggression
Section 15.5: Stress Activates Many Bodily Responses
First-letter Mnemonic Winner: Ellie Chedid - "Shakira’s Hips Don’t Stop For Anyone" for the six basic emotions (surprise, happiness, disgust, sadness, fear, anger)
Page 3: Learning Objectives
Describe, compare, and contrast the James-Lange and Cannon-Bard theories of emotion. Which theory seems more plausible?
Understand the role of the limbic system and Papez circuit in emotional processing and expression.
Examine the prefrontal cortex's role in emotional control and affect (reference: Phineas Gage).
Discuss the amygdala's function in fear and fear learning, including supporting experimental evidence.
Focus: Emotions 2: Neural Mechanisms & Fear (Chapter 15)
Page 4: James-Lange Theory of Emotion
Proposed by William James and Carl Lange
Concept: Emotions result from physiological reactions to events
Example: Scary stimulus triggers increased heart rate
Application: Particularly relevant for strong emotions.
Page 5: Understanding the James-Lange Theory
Summary: A physiological response triggers emotion.
Question: How can similar physiological responses lead to different emotions?
Example: Fear and happiness can arise from similar physiological changes.
Evidence from spinal transection injuries shows individuals can still feel emotions despite loss of bodily signals.
Page 6: Cannon-Bard Theory
Distinction from James-Lange Theory: physiological responses and emotions occur simultaneously rather than sequentially.
Example: Seeing a snake results in feeling fear and physiological reactions (trembling) at the same time.
The character of the emotion is independent of physiological responses.
Page 7: Review of Theories of Emotion
James-Lange: Physiological reaction precedes emotion.
Example: Man perceives snake, reacts physiologically, becomes afraid.
Cannon-Bard: Emotion and physiological reaction are simultaneous.
Example: Fear response occurs at the same time as physiological changes.
Page 8: Emotional Expression and Neuroscience
Emotional expression has profound effects.
Reference: Will Ferrell's character in "Anchorman" expressing emotions.
Affective neuroscience investigates brain regions contributing to emotional experience.
Page 9: Brain Regions Associated with Emotion
Key Question: Is there a specific brain region dedicated solely to emotion?
Answer: No single region; the limbic system is involved in emotional regulation and expression.
Key components include:
Cingulate gyrus/cortex
Hippocampus
Amygdala
Thalamus
Hypothalamus
Page 10: The Limbic System
Proposed by James Papez in the 1930s: links the cortex to subcortical structures.
Role: The cingulate cortex governs emotional experiences alongside other cortical regions.
Evidence shows that damage to the prefrontal cortex disrupts emotion, with specific tumors linked to emotional disturbances.
Page 11: Functions of the Limbic System
The limbic system manages several self-preservation functions.
Note: Prefrontal cortex (PFC) and insula are interconnected but not part of the limbic system.
Page 12: Emotional Processing in the Limbic System
Experimental findings highlight limbic structures' involvement in emotional expression and experience.
Some original limbic circuit components like the hippocampus are not directly associated with emotion but with memory related to fear.
The limbic system is not a singular emotional system, as other brain regions also contribute to emotions.
Page 13: Prefrontal Cortex in Emotions
The PFC influences emotional expression and is involved in cognitive functions.
Emotional coloring indicates that our emotions can shape our perceptions.
Damage to PFC does not impair sensory processing but affects personality and emotional control.
Page 14: Executive Functions of the PFC
Located in the rostral part of the frontal lobe, important for planning and decision-making.
Highly developed in humans, critical for personality and social behavior moderation.
Damage to this area can lead to emotional dysregulation.
Page 15: Phineas Gage Case Study
Significance: Gage’s injury significantly altered his personality and emotional capacity.
Observations: After his accident, he showed impulsive behavior and emotional instability, described as “no longer Gage.” - Dr. John Harlow
Page 16: Teenagers vs Adults in Emotion Recognition
Teens rely on the amygdala for interpreting emotional states, while adults depend more on the prefrontal cortex.
Example: teens express reactions to faces like “shocked” or “angry,” contrasting with adults' reactions to more complex emotions, like “fearful.”
Page 17: Conclusion on Emotional Regulation
Damage to PFC can regress emotional regulation abilities, akin to adolescent behavior.
PFC maturation occurs in the early-to-mid 20s, with significant development starting around ages 11-12.
Page 18: Brain Activation Patterns and Basic Emotions
Distinct basic emotions activate unique brain patterns; no single brain region controls emotion.
Active areas lie in the limbic system but also extend to other regions.
Current understanding is richer for fear, anger, and aggression compared to happiness.
Page 19: Amygdala's Role in Fear
Commonly referred to as the “fear center” but not the sole region for fear processing.
The amygdala is crucial for integrating salient emotions and making fear-related safety decisions.
Page 20: Amygdala Functionality: Experiment
Comparative Video Analysis: Rat behavior changes pre-and post-amygdala lesion regarding fear responses.
Results underscore the amygdala's role in instinctive safety decisions and emotional responses.
Page 21: Klüver–Bucy Syndrome
Resulting from bilateral lesions in the medial temporal lobe (including the amygdala).
Symptoms include hypersexuality, decreased fear and aggression, and abnormal visual recognition behavior.
Lesions significantly reduce normal fear expression in both humans and animals.
Page 22: Case Study: SM
A human subject with amygdala lesions showing fearless behavior in typically fear-inducing situations.
Notable incidents include leading a group through a haunted house without hesitation, indicating a lack of fear response.
Page 23: Further Insights on SM
Despite an absent fear response, SM finds horror films entertaining, indicating a misunderstanding of others' fear responses.
SM demonstrates that diminished fear cannot be solely attributed to a recognition deficit.
Page 24: Thought Questions
Identify brain regions involved in emotional expression, specifically the limbic system and Papez circuit. Support your response with evidence.
Analyze how the case of Phineas Gage informs our understanding of the prefrontal cortex's role in emotional regulation.
Describe the brain regions responsible for fear perception and expression, as well as Klüver-Bucy Syndrome and the case of patient "S.M." and what they reveal about the amygdala's role in fear and learning.
Identify brain regions involved in emotional expression: The limbic system and the Papez circuit play crucial roles in emotional expression. Key brain regions include the cingulate gyrus/cortex, hippocampus, amygdala, thalamus, and hypothalamus. Evidence of their involvement can be drawn from studies demonstrating that damage to the limbic structures can disrupt emotional responses and expressions.
Analyze how the case of Phineas Gage informs our understanding of the prefrontal cortex's role in emotional regulation: The case of Phineas Gage reveals that damage to the prefrontal cortex (PFC) can lead to significant personality and emotional regulation changes. Following his accident, Gage displayed impulsive behavior and emotional instability, which indicates that the PFC is critical for maintaining emotional control and personality continuity.
Describe the brain regions responsible for fear perception and expression: Key areas include the amygdala, which is commonly referred to as the "fear center." The amygdala integrates salient emotions and assists in safety-related decision-making but is not the sole region for fear processing. Klüver-Bucy Syndrome demonstrates the impact of amygdala lesions, resulting in reduced fear and aggression. The case of patient "S.M.," with amygdala lesions, showcases a lack of fear response, which emphasizes the amygdala’s essential role in fear and learning.
Identify brain regions involved in emotional expression: The limbic system and the Papez circuit play crucial roles in emotional expression. Key brain regions include the cingulate gyrus/cortex, hippocampus, amygdala, thalamus, and hypothalamus. Evidence of their involvement can be drawn from studies demonstrating that damage to the limbic structures can disrupt emotional responses and expressions.
Analyze how the case of Phineas Gage informs our understanding of the prefrontal cortex's role in emotional regulation: The case of Phineas Gage reveals that damage to the prefrontal cortex (PFC) can lead to significant personality and emotional regulation changes. Following his accident, Gage displayed impulsive behavior and emotional instability, which indicates that the PFC is critical for maintaining emotional control and personality continuity.
Describe the brain regions responsible for fear perception and expression: Key areas include the amygdala, which is commonly referred to as the "fear center." The amygdala integrates salient emotions and assists in safety-related decision-making but is not the sole region for fear processing. Klüver-Bucy Syndrome demonstrates the impact of amygdala lesions, resulting in reduced fear and aggression. The case of patient "S.M.," with amygdala lesions, showcases a lack of fear response, which emphasizes the amygdala’s essential role in fear and learning.