The principle, based on the theory of René Descartes, that mind and matter are qualitatively different, and that because the mind does not operate within the laws of physics it cannot be investigated scientifically. Descartes also postulated that the mind (or soul) was unique to humans.

Term describing metabolic reactions that result in the breakdown of materials and the release of energy.

An enzyme involved in the process of the removal of highly dangerous hydrogen peroxide from the cell. Catalase catalyses the breakdown of H₂O₂ to H₂O and O₂.

A substance that speeds up a reaction without itself undergoing any overall change in the process.

A class of neurotransmitters and hormones, including dopamine and noradrenalin.

A causal explanation is one given in terms of the mechanisms that underlie behaviour in a given individual at a particular point in time. It should be distinguished from a functional explanation.

The nature of relationships between events in the environment, e.g. that a bell predicts food, or that a lever-press is followed by delivery of food.

The unit of which all living things are composed.

The cycle of growth and division whereby one cell becomes two, involving the replication and exact partitioning of the chromosomes, duplication of all cell constituents and transmission of cellular organisation to the two new cells.

A variety of types of intercellular connections which may also allow cells to communicate with each other. Tight junctions (e.g. between epithelial cells) connect cells together to form a fluid-tight seal. Anchoring junctions, in which the cell’s cytoskeleton joins cells to one another, are found in tissues that are subject to friction and stretching (e.g. muscle tissue in the heart). In the third type, gap junctions, the adjacent cell membranes come extremely close to each other but do not actually touch. At gap junctions, pores in the cell membranes allow the transfer of material from cell to cell.