Long-Term Habituation of Exploration in Rats, Hamsters,

¶ … long-Term habituation of exploration in rats, hamsters, and gerbils by Poucet, Durup, & Thinus-Blanc

Concepts being studied

In this study, the researchers were seeking to study habituation to a novel environment in three species of rodent: rat, hamster, and gerbil. They wanted to see if the animals exhibited habituation behavior each time that they were placed in a new environment, and whether the animals exhibited any between-sessions habituation.

Prior research

Prior research had revealed that hamsters would actively reinvestigate objects during a test session, if, after two sessions of habituation, the spatial relationship between the two objects had changed. Prior research conflicted about whether rats would react to changes in the spatial relationship between objects in a field. They examined prior research and found what appeared to be a specific lack in rats of between-sessions habituation.

What the experimenters attempt to show

The experimenters attempted to show that there was a difference between in-session and between-session habituation rates in some varieties of rodents.

Hypotheses

Habituation of exploration may follow different rules both between and within species according to whether it is assessed on a single session (within session habituation) or on successive sessions (between-session habituation).

Summary of Methods

The researchers used eight each of three different types of rodents: hamsters (75 days old), gerbils (70 days old), and rats (80 days old). They housed them in the same type of facilities, on a 12-hour day-night cycle, and fed them the same type of food. The testing apparatus was a circular field, 105 cm in diameter, with walls 35 cm high, surrounded by white curtains (except one side that had a striped curtain), with an overhead camera. Into the apparatus, the experimenters placed four different objects: a glass jar, a copper weight, a bowl, and a cup in the shape of a square. First the animals were given a 15 minute exploratory phase with no objects in the arena. Then, the experimenter placed the objects into the field; the animals received the first of three 15 minute sessions in the field, with 8 to 10 hours between those sessions. The researchers measured the number of contacts between the animals and the objects, as well as the duration of the contact.

Results

Rats were more active than hamster and gerbils in the number of contacts. The rats spent more time investigating the objects than gerbils, but about the same amount of time as the hamsters. Hamsters and gerbils were roughly the same on the different measures of exploration. The hamsters spent more time during the average contact than other animals.

Interpretation