EFFECTS OF PREVIOUS FAMILIARIZATION ON NOVELTY REACTIONS IN MICE (MUSMUSCULUS)

Mice were at first familiarized with a large novel cage during either 0, 15 min, 1 h, 12 h, 24 h or 48 h. On the following day, they were ob served for a 5-min period after having freely entered the previously e xplored cage. Forty five behavioural items were recorded as well as en trance latency, total time spent in the large cage and transitions bet ween the cage and the nest. Results allowed us to distinguish three gr oups: the most familiarized mice (24 and 48 h), the less familiarized ones (naive and 15 min) and the intermediate group (1 and 12 h). It ap pears that, for the most familiarized mice, there was a topographic co ntinuity between the familiar and the novel environment.