The Neuropsychology of Emotion

Neuropsychology of Emotion

What is Emotion?

The concept of "emotion" is relatively recent, having been coined in the early 1800s by the psychologist Thomas Brown. By the 1830s, the modern understanding of emotion began to culturally and linguistically evolve within the English language.

Modern Study of Emotion

Late 1800s - Charles Darwin (1872)

  • Significant Work: Darwin's publication The Expression of the Emotions in Man and Animals served as a pivotal study in the systematic exploration of emotions.

  • Key Findings:

    • Emotions are not exclusive to humans; they evolved as adaptive responses.

    • Darwin was one of the earliest researchers to undertake a systematic study of emotional expressions, specifically focusing on facial expressions as a means of understanding emotional responses.

Three Components of Emotion (William James)

The exploration of emotion can be structured into three fundamental components:

  1. Behavioral

  2. Physiological

  3. Experiential (Subjective Quality and Cognition)

Behavioral Component

  • Facial Expressions: Research by Paul Ekman identified six basic emotions that manifest through facial expressions:

    1. Anger

    2. Fear

    3. Disgust

    4. Surprise

    5. Happiness

    6. Sadness

  • Body Language:

    • Nonverbal cues reflect emotional states, such as closed body posture indicating insecurity or hostility.

  • Language: Verbal expressions also convey emotional states. For example, saying "hello :)" conveys friendliness or happiness.

  • Social Nature of Humans: These behavioral manifestations highlight the social nature of humans, where emotions are integral to interpersonal interactions.

Physiological Component

  • Autonomic Nervous System Response: This includes changes in:

    • Heart Rate: Increases in heart rate can reflect agitation or fear.

    • Respiration Rate: May accelerate during emotional responses.

    • Perspiration: Sweating can indicate stress or anxiety.

    • Pupil Diameter: Changes can occur in response to emotional stimuli.

  • Purpose of Physiological Changes: They prepare individuals to respond to changing environmental conditions, serving as adaptive responses.

Experiential Component

  • Subjective Quality (Qualia): Emotions are inherently personal experiences that happen to us; we consciously navigate and interpret these emotional states.

  • Cognitive Aspects: This involves interpretation of behavioral, physiological, and subjective experiences, along with personal narratives that inform emotional regulation.

  • Emotional Regulation: How we exert control over our emotional experiences can greatly influence our overall emotional health.

Theories of Emotion

Physiological Theories

  • James-Lange Theory: This theory posits that emotions are the recognition of physiological changes in the body. For example, seeing a shark increases heart rate which subsequently causes the feeling of fear.

  • Cannon-Bard Theory: Contrasts with James-Lange by asserting that physiological responses occur simultaneously with emotional experience, rather than as a result of it. For instance, a heart may pound simultaneously when a person feels afraid.

Cognitive Theories

  • Schachter and Singer's Two Factor Theory: Suggests that physiological arousal must be cognitively interpreted to identify the emotional experience. In a classic experiment, participants injected with adrenaline or saline were more likely to label their emotions based on the emotional state depicted by confederates they interacted with.

  • Implications: When individuals lack a causal explanation for their arousal, they might label their physiological state based on the context or available cognitive information.

CNS and Emotion

Behavioral Responses and Brain Function

  • Patients with lesions in the brain stem, particularly the medulla, have been observed to experience uncontrolled emotional expressions like crying, independent of feeling sad; demonstrating a dissociation between behavioral expressions and emotional feelings.

Physiological Components Involved

Hypothalamus Functions

  • Autonomic Nervous System Regulation: Controls the sympathetic (fight or flight) and parasympathetic (rest and digest) branches.

  • Hormonal Regulation: Influences cardiovascular, respiratory functions, and sweating responses.

Experiential Components

  • The limbic system, particularly the amygdala, plays a crucial role in the subjective experience of emotions, involved in emotional responses including fear learning.

Fear Learning - Joe LeDoux

  • Classical Conditioning of Fear Responses: Involves pairing a neutral stimulus (like a tone) with an unconditioned stimulus (like a shock), leading to a learned fear response.

  • Electrophysiological Studies: In various research contexts, activity in the amygdala was recorded, evidence showing that the lateral amygdala (LA) is critical in forming fear-related memories and responses.

Fear Conditioning in Humans

  • Underlying mechanisms of anxiety and PTSD where neutral stimuli become associated with stress-inducing experiences, making these stimuli evoke fear responses even in their absence.

Amygdala Studies in Humans

  • Generally, significant lesions in the amygdala lead to calmness and an inability to acquire fear-related conditioning, while stimulation of this area can provoke aggressive responses.

Patient Case Studies - Patient SM

  • Case Overview: Patient SM, affected by bilateral amygdala damage due to Urbach-Wiethe disease, exhibits no recognizable behavioral or physiological evidence of fear, instead displaying curiosity toward fear-inducing stimuli. However, she struggles with interpreting and expressing fear through facial expressions.

Role of the Cortex in Emotion

  • Interpretation and Regulation of Emotions: The cortical areas, especially the right hemisphere, contribute significantly to interpretation of emotional stimuli and regulation of emotional responses. Damage to this area can lead to emotional dysregulation, such as difficulties in nuanced emotional expression or understanding humorous situations.

The Impact of Frontal Lobes

  • Phineas Gage Case Study: Exemplifies the frontal lobe's role—personality changes and emotional inhibitions resulting from damage.

  • Prefrontal Lobotomy: Initial studies, including Jacobson's chimp, show reduced emotional outbursts following such procedures, leading to subsequent exploration of these techniques in humans for emotional regulation.

  • Orbitofrontal Cortex Functions: Involved in translating the personal consequences of actions into emotional experiences; patients with this damage fail to apply learned consequences effectively, which can impact decision-making and emotional assessments.