Evocation by Fear of a Habit Learned for Electrical Stimulation of the Brain

Abstract

Rats were trained to press a lever for electrical stimulation of the brain. After extinction of the habit, fear-producing stimuli (a buzzer or electrical shock to the feet) recalled the rat to the lever, although its lever pressing on these occasions never produced further intracranial stimulation. Operant levels of the lever-pressing habit were also greatly increased for long periods following the fear-producing stimuli. The phenomenon is most striking in rats trained with tegmental electrodes and is almost completely absent in rats trained with electrodes in the hypothalamus. This suggests that electrical self-stimulation in some sites may be caused by an activation of mechanisms underlying normal fear and escape.