A contact eatometer suitable for feeding restriction schedules

We describe and test a programmable feeding system based on a contact eatometer, previously developed in our laboratory, consisting of a swinging grid beneath a hopper that is moved by the rat each time it wants to eat. This has now been connected to a solenoid that can block the movement of the grid to prevent access to the food. It also provides a continuous record of food approaches even during restricted periods when no food is made available, and so it is useful in studying the synchronizing role of food in the circadian rhythms of feeding behavior. The simplicity and cheapness of its construction and the effective blocking of access to food make it an ideal tool in chronobiological studies involving the simultaneous use over long periods of a large number of animals.