activate: (in biology) To turn on, as with a gene or chemical reaction.
addiction: The National Institute of Drug Abuse defines this as a complex chronic disorder that is characterized by a difficult-to-control compulsion to use some drug, despite knowing that it will likely have harmful impacts. A first exposure to these drugs is usually voluntary. But repeated use of certain ones, NIDA explains, can create “changes to brain circuits involved in rewards, stress, and self-control.” Those changes can make it very hard to resist the urge to continue using drugs. The term has also been expanded to some behaviors that become dangerous and/or excessive, such as gambling, shopping and video game use.
amygdala: An area deep within the brain and near the temporal lobe. Among other things, the amygdala plays a role in emotions. The term comes from the Greek word for an almond, which this region resembles in shape.
aversive learning: A quick-forming, and long-lasting loathing to the sight, smell or taste of some particular food. It develops after getting sick a short while after eating that food. It can show up after a single instance of linking some food with getting sick — even if the stomach upset or other symptoms didn’t start to show up for several hours.
bacteria: (singular: bacterium) Single-celled organisms. These dwell nearly everywhere on Earth, from the bottom of the sea to inside other living organisms (such as plants and animals). Bacteria are one of the three domains of life on Earth.
cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells.
circuit: A network that transmits electrical signals. In the body, nerve cells create circuits that relay electrical signals to the brain. In electronics, wires typically route those signals to activate some mechanical, computational or other function.
coauthor: One of a group (two or more people) who together had prepared a written work, such as a book, report or research paper. Not all coauthors may have contributed equally.
develop: To emerge or to make come into being, either naturally or through human intervention, such as by manufacturing.
flavor: The particular mix of sensations that help people recognize something that has passed through the mouth. This is based largely on how a food or drink is sensed by cells in the mouth. It also can be influenced, to some extent, by its smell, look or texture.
gut: An informal term for the gastrointestinal tract, especially the intestines.
lever: A rigid bar resting on a pivot. It is used to help move a heavy or firmly fixed load with one end when pressure is applied to the other. Or, as part of some devices, it can act like a switch to turn some system on or off.
link: A connection between two people or things.
literally: An adjective indicating that the phrase it modifies is precisely true. For instance, to say: “It’s so cold that I’m literally dying,” means that this person actually expects to soon be dead, the result of getting too cold.
lithium: A soft, silvery metallic element. It’s the lightest of all metals and very reactive. It is used in batteries and ceramics.
mental health: A term for someone’s emotional, psychological and social well-being. It refers to how people behave on their own and how they interact with others. It includes how people make choices, handle stress and manage fear or anxiety. Poor mental health can be triggered by disease or might reflect a short-term response to life’s challenges. It can occur in people of any age, from babies to the elderly.
neuron: The main cell type of the nervous system — the brain, spinal column and nerves. These specialized cells transmit information by producing, receiving and conducting electrical signals. Neurons also can transmit signals to other cells with chemical messengers.
neuroscientist: Someone who studies the structure or function of the brain and other parts of the nervous system.
potent: An adjective for something (like a germ, poison, drug or acid) that is very strong or powerful.
reward: (In animal behavior) A stimulus, such as a tasty food pellet, that is offered to an animal or person to get them to change their behavior or to learn a task.
symptom: A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.
taste: One of the basic properties the body uses to sense its environment, especially foods, using receptors (taste buds) on the tongue (and some other organs).
trauma: (in medicine) An injury, often a fairly severe one. This term also can refer to a severely disturbing incident (such as a car accident) or memory (such as the death of a loved one).