Emotion

Theories of Emotion

  • Integration of Physiological and Behavioral Processes:

    • Emotion is defined as a subjective mental state often accompanied by distinctive behaviors, cognition, and involuntary physiological changes (Watson & Breedlove).

    • Physiological sensations such as goosebumps, tingly feelings, and fluttering in the stomach are results of autonomic nervous system activation:

    • Sympathetic Nervous System: Known as the “fight or flight” system; it prepares the body for action.

    • Parasympathetic Nervous System: Prepares the body to relax and recuperate.

The Relationship Between Emotions and Bodily Changes

  • James–Lange Theory: Proposes that an autonomic reaction triggers the feeling of an emotion.

  • Cannon-Bard Theory: Suggests that autonomic reaction and feeling occur simultaneously; the perception of specific autonomic arousal equals a specific emotion.

Schachter’s Theory

  • Cognitive Appraisal of Context:

    • Emotional labels are attributed to the sensations stemming from physiological arousal.

    • The specific emotion experienced is dependent on cognitive systems that assess the context of the current situation.

    • The Schachter and Singer experiment illustrates that while autonomic responses may heighten emotions, cognitive appraisal is crucial in determining the specific emotion experienced.

    • Intensity vs. Specific Emotion: There is a distinction where intensity of emotion can be differentiated from the specific emotion felt.

Core Set of Emotions

  • Darwin's Proposition:

    • Charles Darwin suggested that expressions of emotions are universal among all humans and have evolved from those of other species (1872).

    • Similarities in facial expressions between humans and nonhuman primates suggest a common ancestor.

Emotions as Motivational Programs

  • Adaptive Problem Solving:

    • Emotions have evolved to serve as motivational programs that coordinate behaviors and responses to address adaptive problems in the environment:

    • Fear: Responds to aversive situations and threats, enhancing survival.

    • Appetitive Program: Engages in positive situations related to food and mating, also improving survival.

    • Motivational States:

    • Fear increases adaptive behaviors and decreases maladaptive behaviors.

Facial Expressions and Communication

  • Cross-Cultural Similarity:

    • A significant degree of similarity exists across cultures regarding the expressions of specific emotions; however, notable differences can arise in certain isolated groups, particularly for surprise and disgust.

    • Cultural and experiential factors shape the rules governing facial expressions, signifying the complexity of emotional communication.

Cultural Differences in Recognizing Facial Expressions of Emotion

  • Research Findings (After J.A. Russell, 1994):

    • A graph illustrates the percentage of agreement in recognizing various emotional expressions across cultural groups:

    • Expression Categories:

      • Happiness (Ha)

      • Surprise (Su)

      • Anger (An)

      • Sadness (Sa)

      • Fear (Fe)

      • Disgust (Di)

    • Groupings for assessment include (1) non-Western literate (11 groups), (2) isolated nonliterate (3 groups), and (3) Western literate (20 groups).

Emotions in Mice

  • Dolensek et al. Study:

    • Researchers employed a machine learning program to classify various stimuli-driven facial expressions in mice into emotional categories.

    • When coupled with neuron imaging, specific neural circuits were identified in the insular cortex that correspond with facial expressions associated with emotions.

Mechanisms of Facial Expressions

  • Mediated by Muscles and Nerves:

    • Facial expressions arise from muscle contractions controlled by cranial nerves and CNS pathways:

    • Superficial Facial Muscles: Attach between facial skin points.

    • Deep Facial Muscles: Attach to bone, enabling significant movements (e.g., chewing).

    • Cranial Nerves Involved:

    • Facial Nerve (VII) and Motor Branch of Trigeminal Nerve (V).

Facial Feedback Hypothesis

  • Influence of Facial Expression on Mood:

    • Sensory feedback from facial expressions can alter mood states, lending support to the James–Lange theory.

    • Individuals simulating emotions (happy or sad faces) report stronger feelings corresponding to those expressions.

Brain Circuits and Emotions

  • Distinct Brain Circuits for Emotions:

    • Electrical brain stimulation can elicit emotional reactions.

    • Brain Self-stimulation: Animals (including humans) will often work to receive self-administered electrical brain stimulation.

    • Key brain sites supporting self-stimulation have predominantly been identified as subcortical structures located in the medial forebrain bundle.

Medial Forebrain Bundle and Reward Circuitry

  • Function of the Medial Forebrain Bundle:

    • This tract ascends from the midbrain through the hypothalamus and includes multiple sites for self-stimulation.

    • Nucleus Accumbens:

    • Serves as an important target for medial forebrain axons and represents a major component of the reward system; dopamine release in this area induces pleasurable feelings.

Brain Lesions and Emotional Responses

  • Effects of Brain Lesions on Emotion:

    • Decorticate Rage: Observed in dogs post-cortex removal, suggesting the cortex generally inhibits rage responses.

    • James Papez: Proposed that destruction within interconnected brain regions of the limbic system would disrupt emotional processing.

    • Klüver-Bucy Syndrome: Characterized by a significant reduction in fear and anxiety resulting from bilateral amygdala damage.

Amygdala's Role in Emotional Learning

  • Classical Conditioning and Fear:

    • Classical conditioning involves associating a neutral stimulus (tone) with an aversive stimulus (shock), resulting in freezing behavior and increased blood pressure.

    • The amygdala, located in the temporal lobe, is crucial for mediating fear responses during these conditioning processes.

Circuitry of Fear

  • Fear Processing Circuitry:

    • Visual representations of the circuitry involve connections from the thalamus to the sensory cortex and through various pathways leading to the amygdala.

    • High Road Pathway: Involves the sensory cortex and hippocampus, indicating a more processed emotional response.

    • Low Road Pathway: Directly routes sensory information to the amygdala for expedited emotional reactions.

Amygdala Circuitry in Humans

  • Human Studies:

    • Studies demonstrate the same circuitry involved in human emotional response:

    • Temporal Lobe Seizures: Often precede intense fear when involving the amygdala.

    • Patient S.M. (Urbach-Wiethe Disease): Exhibited a lack of fear towards spiders or dangerous individuals; absence of startle response and only recognizes non-fear emotions in others.

Activation of Brain Regions and Emotions

  • Distinct Brain Responses:

    • Activation during the experience of emotions such as love results in:**

    • Increased activity in the insula and anterior cingulate cortex.

    • Decreased activity in the posterior cingulate and prefrontal cortices.

    • A comparative study showed distinct brain activation associated with emotions such as sadness, happiness, anger, and fear but indicated no straightforward linkage between a single emotion and particular brain regions.

    • Exception: The amygdala has a specific, significant role related to fear.