Observational methods used to assess rat behavior: general activity

INTRODUCTIONThe activity-inactivity continuum is an important parameter of behavior, and quantification of overall locomotor activity in the rat should identify it as a naturally nocturnal animal. Disruptions in nocturnal activity can be caused by damage in visual inputs to the brain or damage in the hypothalamus. Many commercial devices are available to measure activity automatically; some can be integrated with a computer to allow overnight monitoring in the absence of an observer. A less sophisticated but still accurate method of measuring activity is to create a home-made activity chamber by replacing the bottom of a box with Plexiglas or by marking lines on the bottom of a clean rat cage so that the observer can record rat activity by noting when the lines are crossed, while simultaneously recording other behaviors. Activity in rat pups can be observed as soon as they are 10 days old using smaller activity chambers. This protocol describes the construction of a home-made activity chamber and how to measure four activities: locomotion, rearing, circling, and grooming.