The effects of superior colliculus lesions on reactions to novelty in the hamster

The aim of this experiment was to examine reactions to novelty of hamsters with large bilateral collicular lesions in an open field containing large conspicuous objects. A video-actographic system was used to quantify the contacts with the objects, the speed of the displacements and the angular head movements. Due to different evolutions of the scores in each group, most of the differences were found at the end of the experiment. Collicular animals, unlike controls, make contacts with the objects but do not habituate, which suggests that these contacts are not investigatory but fortuitous. This possibility is supported by the fact that collicular animals display hyperactive locomotion with stereotyped patterns by the end of the experiment. It is proposed that the depth of lesions and the salience of the stimulus are two modulating factors of the reaction to novelty in collicular animals.