Brown Institute for Brain Science

Novelty Induced Hypophagia Test

Rationale of Test

This task assesses the ability of the animal to resolve a conflict between a context that induces heightened anxiety and a drive to approach an appetitive stimulus. This task is also used as a marker task for assessing potential anxiolytic drug efficacy in humans, as mice require chronic administration of anxiolytics to show decreased anxiety-like behavior on this task.

Apparatus

Training is carried out in the mouse’s homecage and the final day of testing is carried out in a novel brightly lit cage. For monitoring of drinking behavior, we use a near infrared sensitive camera with near infrared light source and record drinking during the training and test phases of this task.

Procedure

Prior to testing, mice are housed 1 per cage for 1 week and then received 3 consecutive days of training (Day1-3) in a darkroom. Training consists of presenting mice with a standard dual bearing sipper tube inserted between the wire bars of the cage roof and containing diluted (1:3; sweetened condensed milk:water). On day 4 mice undergo home cage testing. For testing, the sipper bottle containing sweetened milk is positioned in the wire mesh cage top and then placed back onto the home cage initiating the beginning of the trial. The latency to drink, amount of time spent drinking, and number of drinking sessions is recorded over a 10-min period. All home cage testing occurs in a dark room, and is scored with the aid of an infrared camera. On day 5, novel cage testing is conducted by placing a single mouse into a clean cage of the same dimensions as their home cage, but with no shavings and under bright lighting conditions. Mice are again presented with a sipper tube containing diluted sweetened milk and the latency to drink, duration of drinking, and number of times drinking is recorded over a 10 min period. Anxiety is measured by the relative difference between home and novel cage for (i) the latency to drink, (ii) time spent drinking, and (iii) number of approaches to drink. Using an appetitive stimulus (sweetened milk) no food deprivation will be necessary, as is the case with novelty suppressed feeding.

Interpretation

Increased latency to approach and drink in the novel cage is used to indicate heightened levels of anxiety-like behavior.

Relevant Controls

Care must be taken to insure no differences between groups in motivational status, motor function, gustatory function, or sensory function.

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