Affective Aggression: Hostile or violent behavior that is characterized by impulsiveness and emotional arousal.

Aggression: Forceful or assertive behavior that is intended to harm or control another individual.

Amygdala: A limbic system structure located near the lateral ventricle in each temporal lobe that is involved with a variety of emotions, especially fear and anxiety, and with sexual behavior, aggression, and learning, especially in emotional situations.

Anterior Cingulate Cortex (ACC): A part of the limbic system important in attention, decision making, impulse control, emotion, and possibly consciousness.

Autoimmune Disorder: A disorder in which the immune system attacks the body’s own cells.

B Cell: A type of immune cell that fights intruders by producing antibodies that attack a particular intruder.

Cognitive Theory: A theory that states that a person relies on a cognitive assessment of the stimulus situation to identify which emotion is being experienced; physiological arousal determines the intensity of the emotional experience.

Congenital Insensitivity to Pain: A condition, present at birth, in which the person is insensitive to pain due to a genetic pathology in the peripheral nervous system.

Cortisol: A hormone released by the adrenal cortex that produces physiological stress responses, including increases in metabolism, glucose availability, and blood supply to the skeletal muscles. The increase is more sustained than that produced by epinephrine and norepinephrine.

Emotion: A state of feelings accompanied by an increase or a decrease in physiological activity and often by characteristic facial expression and behavior.

Hypothalamus-Pituitary-Adrenal Axis: A group of structures that help the body cope with stress.

Immune System: The cells and cell products that kill infected and malignant cells and protect the body against foreign substances, including bacteria, viruses, toxins, and pollen.

James-Lange Theory: The idea that physiological arousal precedes and is the cause of an emotional experience and that the pattern of arousal identifies the emotion.

Leukocytes: White blood cells, which include macrophages, T cells, and B cells; part of the immune system.

Limbic System: A group of forebrain structures arranged around the upper brain stem that have roles in emotion, motivated behavior, and learning.

Macrophage: A type of leukocyte that ingests intruders.

Microglia: Glial cells that provide immune protection in the central nervous system by acting as macrophages.

Mirror Neurons: Cortical neurons that respond when engaging in an act and while observing the same act in others; found in the premotor cortex, supplementary motor area, primary somatosensory cortex, and inferior parietal cortex.

Natural Killer Cell: A type of immune cell that attacks and destroys certain kinds of cancer cells and cells infected with viruses.

Predatory Aggression: Hostile or destructive behavior in which an animal attacks and kills its prey or a human engages in a premeditated, unprovoked, and similarly relatively emotionless attack.

Proactive/instrumental Aggression: Unprovoked and emotionless hostile or violent behavior intended to result in gain for the aggressor, such as to intimidate, dominate, or rob the victim.

Reactive/impulsive Aggression: Hostile or violent behavior resulting from a threat (real or imagined) to the individual, characterized by heightened emotionality.

Skin Conductance Response (SCR): A measure of sweat gland activation and thus sympathetic nervous system activity.

Stress: A condition in the environment that makes unusual demands on the organism, such as threat, failure, or bereavement; the individual’s negative response to a stressful situation.

Sudden Cardiac Death: A fatal event when stress causes excessive sympathetic activity that sends the heart into fibrillation, contracting so rapidly that little or no blood is pumped.

T Cell: A type of leukocyte whose four types either attack invaders or help regulate the immune system.