Emotion

Biopsychological Investigation of Emotion

  • Phineas Gage (1848):

    • Tamping iron through medial prefrontal lobes altered his personality, demonstrating a link between brain structure and emotional regulation.

  • Darwin’s Expression of Emotions in Man and Animals:

    • Proposed that emotions evolved from survival signals (telegraphed behavior).
    • Principle of Antithesis: Suggests opposing emotional expressions to indicate different emotional states.
    • Aggressive dog posture: ears forward, back up, hair up, tail up.
    • Submissive dog posture: ears back, back down, hair down, tail down.

  • Theories of Emotion:

    • James-Lange Theory:
      • Emotions are a result of physiological changes triggered by stimuli.
    • Cannon-Bard Theory:
      • Emotional stimuli provoke both visceral and emotional responses simultaneously.
    • Third Theory:
      • Interaction between perception of an emotional stimulus, autonomic/somatic responses, and emotional experience.

  • Sham Rage (1929):

    • Observed in decorticate cats showing aggression to minimal provocation, highlighting the hypothalamus's role in aggressive behavior.

  • Limbic System:

    • Papez (1937) identified structures controlling emotional expression, located around the thalamus.

  • Kluver-Bucy Syndrome:

    • Caused by damage to the amygdala, resulting in fearless behavior, hypersexuality, and tactile exploration of objects.

Emotions and the Autonomic Nervous System

  • Emotional Specificity:
    • A nuanced interaction between James-Lange and Cannon-Bard theories.
    • Polygraphy: Measures emotional changes via the autonomic nervous system using techniques like control-question and guilty-knowledge methods.

Emotions and Facial Expression

  • Universality of Facial Expressions:

    • Cross-cultural studies show agreement on primary facial expressions (Ekman and Friesen identified six primary expressions).

  • Facial Feedback Hypothesis:

    • Study by Rutledge and Hopke (1985) showed emotions influenced by facial expressions (happy face → more happiness).
    • Concepts of voluntary control over facial expressions, microexpressions, and genuine smiles (Duchenne smile).

  • Facial Expressions: Current Perspectives:

    • Recognizes complexity in primary emotions; body cues also play significant roles.

Aggression, Defense, and Stress

  • Colony Intruder Model:

    • Developed by Blanchard and Blanchard, linking aggression and defense as a unified behavioral response.
    • Lesion data indicates the role of septal nuclei in aggression (septal rage).

  • Aggression and Testosterone:

    • Testosterone positively correlates with social aggression, but results vary between species and contexts.

Neural Mechanisms of Fear Conditioning

  • Fear Conditioning:

    • Involves pairing a neutral stimulus (conditional stimulus) with an aversive stimulus (unconditional stimulus).

  • Amygdala and Fear Conditioning:

    • Lesions to the medial geniculate nucleus disrupt fear conditioning through connections with the amygdala.
    • Involves both direct and indirect routes to mediate sympathetic responses.

  • Contextual Fear Conditioning and Hippocampus:

    • Hippocampal lesions hinder fear conditioning related to context, indicating its role in memory and emotional responses.

Brain Mechanisms of Human Emotion

  • Cognitive Neuroscience of Emotion:

    • Emotions activate diffuse brain areas; motor/sensory cortices engaged during emotional experiences.

  • Amygdala:

    • Especially responsive to fear; significant in emotional processing, seen in conditions like Urbach-Wiethe Disease.

  • Medial Prefrontal Lobes:

    • Involved in moderating emotional reactions, particularly in suppression and re-evaluation scenarios.

  • Lateralization of Emotion:

    • Discusses two dominant models (Right hemisphere & Valence models) and suggests these might be overly simplistic.

Stress and Health

  • Definitions of Stress:

    • Refers to physiological responses upon exposure to threats or harm.
    • Stressors are experiences causing this response.

  • Stress Response Systems:

    • Involves hormonal systems like the anterior pituitary-adrenal cortex and sympathetic nervous system, leading to the release of glucocorticoids, epinephrine, and norepinephrine.

  • Psychosomatic Disorders:

    • Disorders such as gastric ulcers, influenced by psychological factors alongside physical conditions (e.g., Helicobacter pylori).

  • Psychoneuroimmunology:

    • Examines interactions between psychological factors, the nervous system, and immune system functioning, highlighting how stress affects immune responses.

  • Effects of Early Stress:

    • Early stress can adversely affect development and make individuals more sensitive to future stressors.

  • Stress Impact on the Hippocampus:

    • Stress can lead to structural changes in the hippocampus, affecting neurogenesis and cognitive function, particularly mediated by glucocorticoids.