Floor vibrations for motivation and feedback in the rat vibration actuating search task.

Abstract

Motivating rodents to perform cognitive tasks often relies on the application of aversive stimuli. The Vibration Actuating Search Task (VAST) is a novel open-field task in which gradient floor vibration provides motivation for the rodent to navigate in the direction of diminishing vibration to an unmarked target destination. Using floor vibration as a motivational stimulus may overcome several of the potential confounds associated with stimuli used in other tasks. In a series of three experiments, we determined whether (1) rats exhibit place preference for floor vibration over other aversive stimuli (i.e., water, foot shock, and bright light), (2) exposure to floor vibration is associated with a lower corticosterone response than exposure to these other stimuli, (3) rats successfully acquire the VAST, and (4) VAST performance is sensitive to 6 h of sleep deprivation (SD). Our results showed that rats exhibited place preference for vibration over water, foot shock, and bright light environments, and that corticosterone levels were lower in rats exposed to vibration than those exposed to water. VAST performance also significantly improved over two days of testing for some metrics, and SD impaired VAST performance. Overall, we conclude that (1) rats exhibit place preference for vibration over other stimuli commonly used to motivate task performance, (2) the vibrations employed by the VAST produce lower concentrations of circulating corticosterone than forced swimming, (3) rats can learn to use gradient floor vibration as a mode of performance feedback within two days of testing, and (4) VAST performance is substantially impaired by SD. Thus, the VAST is an effective and practical testbed for studying the mechanisms by which SD causes deficits in feedback-dependent decision making.