Class 6 Aggression

Emotion

Complex response consisting of cognitive, physiological, and behavioral components.

Cognitive Component

Thoughts, beliefs, and perceptions that influence emotions.

Physiological Component

Autonomic and endocrine bodily changes that accompany emotions.

Behavioral Component

Observable actions such as freezing, hiding, fighting, or fleeing.

Fight-or-Flight Response

Automatic survival response that prepares the body to respond to threats.

Autonomic Nervous System (ANS)

Controls involuntary physiological responses during emotions.

Sympathetic Nervous System

Activates the body during stress by increasing heart rate, blood pressure, and energy availability.

Parasympathetic Nervous System

Restores the body to a relaxed state after a threat has passed.

Sympathetic-Medullary-Adrenal (SAM) Axis

Fast stress response that releases adrenaline and noradrenaline for immediate action.

Hypothalamic-Pituitary-Adrenal (HPA) Axis

Slower stress response that releases cortisol to maintain long-term homeostasis.

Adrenaline

Hormone released during the SAM response that increases heart rate and energy.

Noradrenaline

Hormone and neurotransmitter that increases arousal, vigilance, and blood pressure.

Cortisol

Stress hormone released by the HPA axis that regulates long-term stress responses.

Negative Feedback

Mechanism that reduces HPA axis activity once cortisol levels are sufficient.

Aggression

Behavior intended to threaten or harm another individual.

Predation

Behavior involving hunting, killing, and consuming prey for survival.

Offensive Aggression

Attack behavior directed toward another individual.

Defensive Behavior

Protective behavior used to avoid or respond to threats.

Submissive Behavior

Behavior that reduces conflict by yielding to another individual.

Maternal Aggression

Aggressive behavior used to protect offspring.

Social Aggression

Aggression related to social hierarchy or competition.

Limbic System

Brain network involved in emotion, motivation, memory, and aggression.

Ventromedial Prefrontal Cortex (vmPFC)

Brain region that inhibits impulsive behavior and regulates aggression.

Amygdala

Processes fear, anger, emotional memories, aggression, and threat detection.

Basolateral Amygdala (BLA)

Receives sensory and contextual information and integrates emotional signals.

Central Amygdala (CeA)

Coordinates autonomic and behavioral emotional responses.

Medial Amygdala (MeA)

Contributes to emotional responses and consolidation of emotional memories.

Hippocampus

Provides contextual memory information during emotional processing.

Hypothalamus

Controls physiological, hormonal, and autonomic responses to emotions.

Paraventricular Nucleus (PVN)

Hypothalamic nucleus that activates the HPA axis by releasing CRH.

Periaqueductal Gray (PAG)

Brainstem region coordinating defensive behaviors, aggression, predation, and pain modulation.

Aggression Circuit

vmPFC/Hippocampus/Thalamus → Amygdala → Hypothalamus → PAG → Aggressive behavior.

Impulse Control

Ability to inhibit inappropriate behaviors through vmPFC regulation.

Emotional Regulation

Process of controlling emotional responses through interactions between the vmPFC and amygdala.

Decision Making

Process involving the vmPFC to evaluate risk and behavioral consequences.

Homeostasis

Maintaining stable internal physiological conditions.

Optogenetics

Technique using light to activate or inhibit specific neurons.

Calcium Imaging

Method for visualizing neuronal activity by measuring calcium signals.

AAV-Mediated Genetic Manipulation

Method for modifying gene expression in targeted neurons.

Serotonin (5-HT)

Neurotransmitter that suppresses impulsive aggression by enhancing vmPFC control over the amygdala.

Low Serotonin

Associated with aggression, impulsivity, antisocial behavior, and risk-taking.

Dopamine

Neurotransmitter associated with reward-driven aggression.

Noradrenaline (NE)

Facilitates aggression by increasing arousal during stress.

GABA

Main inhibitory neurotransmitter that suppresses neural activity.

Glutamate

Main excitatory neurotransmitter that increases neural activity.

5-HIAA

Major serotonin metabolite used as an indicator of serotonin activity.

SSRIs

Selective serotonin reuptake inhibitors that increase serotonin signaling and reduce aggression.

Tryptophan

Serotonin precursor that can increase serotonin synthesis.

Serotonin Receptor Agonist

Drug that activates serotonin receptors to reduce aggression.

Genetic Influence on Aggression

Twin and adoption studies show aggression is partly heritable.

Twin Studies

Identical twins show greater similarity in aggressive behavior than fraternal twins.

Adoption Studies

Aggression is more similar between biological relatives than adoptive relatives.

Testosterone

Sex hormone strongly associated with increased aggression and reduced impulse control.

Testosterone-Cortisol Ratio

High testosterone combined with low cortisol predicts higher aggression.

Estrogen

Female sex hormone that can influence aggression depending on menstrual cycle stage.

Progesterone

Hormone that may influence aggressive behavior through hormonal fluctuations.

Oxytocin

Hormone promoting social bonding and reducing aggression.

Arginine Vasopressin (AVP)

Neuropeptide involved in regulating aggression through the limbic system.

Alcohol

Can increase aggressive behavior by impairing prefrontal cortical control.

Chronic Stress

Reduces serotonergic function and increases vulnerability to impulsive aggression.

Parkinson's Disease

Neurodegenerative disorder that can impair serotonergic neurotransmission.

Alzheimer's Disease

Neurodegenerative disorder associated with altered serotonin signaling.

Traumatic Brain Injury

Can damage prefrontal and serotonergic pathways involved in impulse control.