Biological Theories II - Polyvagal Theory

Biological Theories and Personality Perspectives

• General Biological Framework:     * Individual differences are examined across multiple dimensions:         * Behavioral Level: Visible actions and reactions.         * Personality Level: Traits and dispositions as defined in dispositional theories.         * Biological Level:             * Functioning of the Central Nervous System (CNS).             * Hormonal levels and endocrine activity.             * Functioning of the Vegetative Nervous System (VNS) / Autonomic Nervous System (ANS).     * Core Principle: The central focus of biological theories is REGULATION.     * Vegetative Nervous System Role: All organs are regulated to maintain homeostatic balance.

Organization of the Nervous System

• Central Nervous System (CNS): Consists of the Brain and Spinal Cord.

• Peripheral Nervous System (PNS):     * Afferent Division: Carries input from the periphery to the CNS.         * Sensory Stimuli: External environmental data.         * Visceral Stimuli: Internal organ data.     * Efferent Division: Carries output from the CNS to the periphery.         * Somatic Nervous System: Motor neurons controlling skeletal muscles.         * Autonomic Nervous System: Regulates smooth muscle, cardiac muscle, exocrine glands, and some endocrine glands.             * Sympathetic Nervous System: Focused on mobilization.             * Parasympathetic Nervous System: Focused on conservation and restoration.             * Enteric Nervous System: Dedicated specifically to digestive organs and stimuli in the digestive tract.

Functional Divisions of Autonomic Nerves

• Parasympathetic Nerves ("Rest and Digest"):     * Physiological Effects:         * Constricts pupils.         * Stimulates saliva production.         * Slows heartbeat.         * Constricts airways.         * Stimulates stomach activity.         * Inhibits glucose release; stimulates the gallbladder.         * Stimulates intestinal activity.         * Contracts the bladder.         * Promotes erection of genitals.     * Anatomical Origin: Primarily Cranial and Sacral nerves.

• Sympathetic Nerves ("Fight or Flight"):     * Physiological Effects:         * Dilates pupils.         * Inhibits salivation.         * Increases heartbeat.         * Relaxes airways.         * Inhibits stomach activity.         * Stimulates glucose release; inhibits the gallbladder.         * Inhibits intestinal activity.         * Secretes epinephrine and norepinephrine.         * Relaxes the bladder.         * Promotes ejaculation and vaginal contraction.     * Anatomical Origin: Thoracic and Lumbar nerves.

Theoretical Foundations of Vegetative Regulation and Personality

• Eysenck (1967, 1985): Proposed that Neuroticism is directly related to the sensitivity of the vegetative nervous system. Individuals with high neuroticism have "emotion-related areas that are easily triggered," leading to increased learning from punishment.

• Lacey (1967): Associated the regulation of Heart Rate (HR) with an individual's attitude toward seeking or avoiding stimuli.

• Cannon (1926) and Selye (1936): Identified that stress reactivity is regulated by the sympathetic nervous system via the "Fight or Flight" system.

• Stephen Porges (1995): Developed the Polyvagal Theory, an integrated theory connecting biology, evolution, and social behavior.

Phylogeny: Evolutionary Development of Heart Rate Regulation

• Conceptual Overview:     * History of species evolution (phylogeny) shows a progression in how the heart is regulated.     * Decreased Heart Rate: Represents inhibitory processes.     * Increased Heart Rate: Represents excitatory processes.

• Evolutionary Stages:     1. Jawless Fish: Only Endocrine stimulation (hormonal). This is a slow process as hormones must decompose for stimulation to cease.     2. Cartilaginous Fish: Endocrine stimulation combined with Neural Inhibition (Dorsal Vagal Complex - DVC). Stimulation remains slow (hormonal), but inhibition is fast (neural).     3. Bony Fish, Amphibians, and Reptiles: Endocrine stimulation, Neural inhibition (DVC), AND Neural stimulation (Sympathetic Nervous System - SNS). This allows for fast stimulation and inhibition; endocrine stimulation becomes secondary.     4. Mammals: Integration of all previous systems plus the Ventral Vagal Complex (VVC). This allows for nerve stimulation and inhibition within the same neural pathway.

Heart Rate Regulation in Mammals

• The Sinus Node: Defines the heart rate frequency.

• Neural Contact: Parasympathetic pathways are in direct contact with the sinus node.

• Baseline Rates:     * The sinus node naturally beats at approximately $200 \, \text{beats per minute}$.     * The Vagus Nerve inhibits this to produce an average resting heart rate of $\sim 72 \, \text{bpm}$.

• Rapid Response: To increase heart rate quickly, the myelinated vagus nerve simply withdraws inhibition ("vagal brake"), avoiding the need to switch between different nerve pathways.

The Dual Tracks of the Vagus Nerve

• The Dorsal Vagus (Ancient System):     * Phylogenetically older (present in cartilaginous fish).     * Consists of unmyelinated axons.     * Controls "rest and digest" and immobilization behaviors.

• The Ventral Vagus (Newest System):     * Unique to mammals.     * Consists of myelinated axons starting from the Nucleus Ambiguus.     * Enables social capacities and interactions.     * Face-Heart Connection: Vagal efferent pathways shifted from the dorsal nucleus (reptiles) to the nucleus ambiguus (mammals), linking social engagement with visceral states.

Polyvagal Theory Levels and Neuroception

• Neuroception: The nervous system's subconscious evaluation of risk in the environment, choosing an adaptive response among three levels:     1. Level 3: Safety (Myelinated Vagus/VVC): Supports visceral homeostasis and spontaneous social connection (eye contact, facial expressions).     2. Level 2: Danger (Sympathetic NS): Mobilization defense; the "Fight or Flight" response.     3. Level 1: Danger to Life (Non-myelinated Vagus/DVC): Immobilization defense; "Freeze" or pretending to be dead.

Functional Subsystems in Polyvagal Theory

Hierarchical Inhibition and Adaptive Behavior

• Systems operate in a hierarchy where higher (newer) systems inhibit lower (older) ones:     * VVC (1st system) inhibits SNS (2nd system).     * SNS (2nd system) inhibits DVC (3rd system).

• Adaptivity: Behavior is adaptive when bonding or defense matches the actual environmental risk through "real" neuroception.

• The Social Interaction Example: In a social situation (e.g., someone asking "You also study psychology here?"), a person might perceive danger and walk away (SNS/DVC activation) or engage safely (VVC activation).

Maladaptive Behavior and Clinical Implications

• Problems with Neuroception:     * Interpreting situations as life-threatening when safe (e.g., Selective Mutism).     * Perceiving danger where there is none (e.g., Borderline/Paranoid Personality Disorder).     * Perceiving safety where there is danger (e.g., Williams Syndrome).

• Individual Differences in Vagal Sensitivity:     * Example 1: Speed and method of HR increase when shifting from calm to exercise.     * Example 2 (BPD Study): In social conflict, BPD groups show decreased vagal tone and SNS activation, whereas control groups show increased vagal tone.

• Therapeutic Assumption: Functional subsystems remain neuroanatomically intact; hence, therapy can "recalibrate" the system.

Criticisms and Empirical Support

• Criticisms:     * Edwin W. Taylor: No scientific evidence for distinct functions of myelinated/unmyelinated vagus; lacks 100% anatomical match.     * Lack of evidence for one system being more "primitive" than another.     * Overlaps significantly with existing attachment and social neuroscience models.     * Shelley E. Taylor: Proposes an alternative female stress response called "Tend and Befriend," which Uvnas argues is distinct from VVC "Calm and Connection."

• Empirical Support:     * Found in developmental literature (fetal autopsies).     * Found in trauma literature.     * Clinical data: Low vagal tone is correlated with BPD and high sensitivity to danger.

Optimum Arousal and the Window of Tolerance

• Mogyorósy-Révész (2019, 2021) Model:     * Hyperarousal Zone (SNS): Fight/Flight. Symptoms: HR increase, tension, racing thoughts, rumination.     * Optimum Arousal / Tolerance Window (VVC): Ventro-vagal social reaction. The zone where emotional regulation is maintained.     * Hypoarousal Zone (DVC): Immobilization. Symptoms: Numbness, disconnectedness, total shutdown.

• Personality Implications: How much time one spends outside the optimum zone and how wide the zone is define emotional stability.

Emotion Regulation Dynamics (Gross, 2014)

• Process of Emotion: Situation $\rightarrow$ Appraisal (reporting) $\rightarrow$ Response (neurobiological/physical) $\rightarrow$ Feedback (modifying future appraisal).

• Regulation Points:     * Choosing the Situation: Avoiding negative triggers.     * Changing the Situation: Directing attention to self.     * Attention Modification: e.g., Scrolling Instagram to distract.     * Cognitive Reframing: Changing the interpretation of the event.     * Changing the Answer: Physical intervention (e.g., deep breathing).

Trauma and the Brain (van der Kolk, 2014)

• Trauma Definition (APA, 2025): Emotional response to terrible events (accidents, abuse, neglect). Symptoms include unpredictable emotions, flashbacks, and physical symptoms.

• Neural Processing: The Limbic system has primacy. Information flows: Thalamus (sensory) $\rightarrow$ Amygdala/Hippocampus (emotion/memory) $\rightarrow$ Prefrontal lobe (conscious processing).

• Triune Levels of Functioning:     1. Basic Regulation (bottom).     2. Gut feelings and automatic reactions (middle).     3. Cognitive functions/language/planning (top).

Therapeutic Applications and Safety

• Goal: Creating a safe space to recalibrate the vagal inhibition system and neuroception.

• Requirements for Social Connection: Defensive structures must be inhibited; this requires a high vagal tone and low HR.

• Factors of Success:     * Secure attachment and satisfaction of basic emotional needs.     * Rogers’ Triad: Congruence, unconditional positive regard, and empathy.     * Interventions: Mindfulness, Yoga-type exercises, and Schema therapy (Young et al., 2003).     * Widening the Tolerance Window: Learning to cope with hyper- and hypoarousal; moving beyond purely cognitive techniques to include "affect bridge" or breathing exercises.