bnb week 12

PSY1BNB WEEK 12 – Cognition & Emotions: Emotions

Instructor Information

  • Dr. Kathryn Baker

  • Email: PSY1BNB@latrobe.edu.au

Week 12 Lecture Outline

  • Part 1: Emotions

  • Part 2: Fear

  • Part 3: Reward

Reading Materials

Prescribed Readings

  • Hedges, V. (2022): Introduction to Neuroscience (MSU). Free access at: MSU Open Books

    • Chapter 58: Emotions: Overview

    • Chapter 59: Emotions: Fear

    • Chapter 48: Motivated Behavior: Reward Pathway

Recommended Readings

  • Breedlove, S.M. & Watson, N.W. (2023): Behavioral Neuroscience (10th or 9th ed.). Sunderland, MA: Sinauer Associates, Inc.

    • 10th Edition: Sections 15.1-15.3 (pp. 491-511) in Chapter 15 Emotions, Aggression, and Stress

Part 1: Emotions

What is Affective Neuroscience?

  • Affect: Refers to the experience of emotions, moods, and feelings.

  • Affective Neuroscience: Examines how the brain creates emotional responses.

    • Involves bodily changes (e.g., facial expressions), changes in autonomic nervous system activity (e.g., increased heart rate), subjective feelings (e.g., fear), and urges to act (motivations) (Izard, 2010).

    • Leads to biological treatments for:

    • Affective disorders (e.g., depression, anxiety).

    • Other disorders (e.g., PTSD, addiction).

Studying the Neural Control of Emotion

  • Human Studies:

    • Methods: Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI).

    • Studies of individuals with brain lesions due to accidents or diseases.

  • Animal Studies: (e.g., rats, mice, voles, monkeys)

    • Methods: Pharmacology, hormones, lesioning, and electrode implantation (electric physiology, optogenetics).

    • Neural circuits function similarly to human affective networks.

Why Do Organisms Have Emotions?

  • Evolutionary Perspective:

    • Emotions are organized around the survival and reproductive needs of organisms.

    • Argued to have evolved to coordinate adaptive behavioral responses.

    • Based on Charles Darwin's 1872 work, "The Expression of Emotions in Man and Animals," suggesting that similar emotional responses are found across cultures and in nonhumans.

Theories of Emotion

  • Connection Between Arousal and Cognitive Perception:

    • Theories focus on the relationship between physical arousal and cognitive perception:

    • Do emotions cause bodily changes, or do bodily changes cause emotions?

  • James-Lange Theory:

    • States that specific arousal patterns from stimuli are perceived as distinct emotions.

    • The brain interprets physiological and behavioral changes as emotion and produces a cognitive response to autonomic information.

    • Critique: Lack of distinctive autonomic patterns for each emotion.

  • Basic Emotion Theory:

    • Views emotions as biological, universal, and adaptive:

    • Fear -> Avoid danger

    • Disgust -> Avoid/expel poisonous food

    • Anger -> Manage a physical threat

    • Guilt -> Avoid social rejection or maintain group membership

    • Embarrassment -> Avoid social rejection and communicate awareness of social norm violation

    • Joy -> Seeking valuable mates

    • The brain integrates resources to meet needs for action and growth.

    • Critique involves the number of emotions and cultural differences in expressions.

  • Cannon-Bard Theory:

    • Suggests stimuli simultaneously trigger both arousal and cognitive states.

    • Identified cognitive appraisals as crucial despite some findings indicating emotions can precede physiological responses.

  • Cognitive Appraisal Theory:

    • Highlights the importance of cognitive appraisals in determining emotions.

    • Based on Schachter-Singer’s Theory:

    • Stimuli cause general arousal, which is interpreted as specific emotions based on context.

    • Two views: conscious appraisals cause emotions and vice versa.

The Neural Control of Emotion: Components of Experience

  • Types of Emotional Experience and their neural bases:

    • Autonomic response (e.g., increased heart rate): mediated by hypothalamus and brainstem.

    • Subjective feelings (e.g., fear): mediated by the amygdala and frontal lobes.

    • Cognitions (e.g., thoughts about the experience): mediated by the cerebral cortex.

The Limbic System

  • The limbic system is complex and no consensus on which structures it includes.

  • Structures involved in emotion circuitry:

    • Brainstem, Thalamus, Amygdala, Nucleus Accumbens, Hippocampus, Prefrontal Cortex, Orbitofrontal Cortex, Hypothalamus, Insula.

  • Contemporary conception of the limbic system includes a range of structures from primitive to advanced areas of the brain (Kolb, Whishaw & Teskey, 2023).

Learning Outcomes for Part 1: Emotions

  • Differentiate between James-Lange, Cannon-Bard, and Cognitive Appraisal Theories.

  • Articulate strengths and limitations of each theory.

  • Describe three components of emotional experience and their neural control implications.

Part 2: Fear

Fear Memories and Adaptation

  • Fear is adaptive for survival and involves behavioral responses to perceived threats.

  • Subjective response is fear, modified by knowledge, experience, and context.

  • Fear signals to others about nearby threats.

Early Studies of Fear and Brain Function

  • Temporal Lobe Lesions and Emotions in Monkeys:

    • Klüver–Bucy syndrome: results from bilateral removal of large portions of the temporal lobe, characterized by reduced fear, aggression, hypersexuality, and visual agnosia; identified the amygdala as key in fear mediation.

  • Human Cases of Amygdala Lesions:

    • Some individuals develop Klüver–Bucy syndrome with flattened emotions, showing little to no fear in response to external threats (e.g., patient S.M.).

External vs. Internal Threats

  • Patients with amygdala lesions do not feel fear but may respond to internal threats like hypoxia.

Implications of Amygdala Function Loss

  • Resiliency to excessive fear disorders (e.g., PTSD) but vulnerability to panic disorder from low amygdala activity.

Conservation of Neural Mechanisms Across Species

  • The amygdala is crucial for processing emotional significance of sensory stimuli. (LeDoux, 1992)

Studying Fear Conditioning

  • Innate vs. Learned Fear:

    • Fear conditioning involves pairing a neutral stimulus with an unpleasant experience, resulting in a conditioned fear response.

  • Causal Evidence of Amygdala’s Role:

    • Lesions and manipulations of the amygdala hinder fear learning; evidence of conditioned fear responses and memory storage.

Fear Expression Circuitry

  • Circuitry of fear involves sensory information from the thalamus to the amygdala for immediate reactions bypassing conscious processing.

Inhibiting Fear via Extinction

  • Extinction weakens learned behavior by removing the reinforced outcome, leading to potential relapse. Therapies for fear reduction are based on this principle.

Optogenetics in Fear Research

  • Genetically modified neurons can be activated or inhibited with light to influence extinction memory strength in the infralimbic cortex.

Neural Networks of Fear

  • Key brain regions include the amygdala, ventromedial prefrontal cortex (vmPFC), and anterior cingulate cortex (ACC) which help regulate fear and anxiety.

Developmental Differences in Fear Regulation

  • Fear extinction is diminished in adolescence, leading to vulnerability to anxiety disorders.

Learning Outcomes for Part 2: Fear

  • Describe symptoms of amygdala lesions in humans and temporal lobe lesions in monkeys.

  • Summarize experimental evidence of the amygdala's involvement concerning external and internal threats.

  • Evaluate the conservation of structure and function of the amygdala across species.

Part 3: Reward

Evolution of Reward Mechanisms

  • Reward mechanisms benefit individual members and the species as a whole.

  • Natural rewards vs. nonnatural rewards.

  • Brain regions processing rewards are highly conserved (e.g., eating, social bonding, sex, drug abuse).

Components of Reward by Berridge and Robinson (2003)

  • Three main components:

    • Learning about rewards (CS-US learning)

    • Motivation for rewards (“wanting”)

    • Affective responses to pleasure (“liking”)

Studying Reward Mechanisms

  • Electrical Stimulation of the Brain: Intracranial self-stimulation has been used for research; animals and humans will perform behaviors to receive brain stimulation.

  • Reward Circuits and Self-Stimulation: The medial forebrain bundle and nucleus accumbens are crucial pleasure targets.

Dopamine Pathways in Reward Processing

  • The mesolimbic pathway involves dopamine release in the nucleus accumbens, while the mesocortical pathway involves prefrontal cortex action for decision making and inhibition.

Independent Processes of Wanting and Liking

  • “Wanting” involves dopamine, while “liking” involves opioid and endocannabinoid systems.

Dopamine’s Role in Reward Prediction

  • Dopamine neurons signal reward prediction errors, boosting motivation to pursue rewarded behavior.

The Amygdala’s Role Beyond Fear

  • The amygdala plays a role in appetitive learning, enhancing motivation for certain learned cues, like food, despite adverse conditions.

Hedonic Networks in the Brain

  • Pleasure is conceived as a hedonic gloss from brain activities in hedonic hotspots or cold spots.

Learning Outcomes for Part 3: Reward

  • Describe the components of Berridge and Robinson’s reward model.

  • Evaluate the implications of self-stimulation studies on reward circuits.

  • Understand key brain regions and neurotransmitters involved in liking and wanting systems and their clinical implications.