Two amygdala (plural: amygdalae) sit in the temporal lobe on either side of the brain. The amygdala mediates aggressive behavior, anxiety, and innate and learned fear.

The ANS has two parts: the sympathetic nervous system (SNS) and the parasympathetic nervous system (ANS). The PNS mediates the body’s response to arousing or stressful circumstances, triggering automatic responses like fight/flight and sexual arousal. The parasympathetic nervous system calms the body and triggers relaxation for events like sleep.

The study of animal behavior through solely observable phenomena, ignoring mentation. This field proposes that all behavior can be explained via operant conditioning; association will be taught between an action and consequence, thereby promoting or inhibiting the action.