Abstract

Stepping on a strongly electrified grid is highly aversive. A desperately hungry rat - even a rat who hasn't eaten for 10 days - won't run across an electrified cage-floor to reach a food-source: the shocks are too painful. But a rat with electrodes implanted in its neural reward circuitry will cross the grid, repeatedly, to gain the chance to self-stimulate its pleasure centres. Direct electrical stimulation of the mesolimbic dopamine system is so overpoweringly delightful that the anticipated reward eclipses the immediate pain