Lateralized display of spontaneous exploratory behaviour induced by novelty in intact rats: Effects of geometrically different environments

Laterality is conceived as a functional property of the brain, where parallel neural circuits modulate complementary aspects of one function. Well known examples are handedness and speech in humans. Laterality also is present in animals indicating a general evolutionary functional aspect and not a single distinctive trait of humans. In the present work, the consistency of one lateralized response in the spontaneous behaviour of exploration, driven by novel environments with different geometrical proportions was studied in rats. Consistency of response was considered when the animal shows the same preferential display in different testing contexts. Three geometrical forms of environments (square, rectangle and T shaped environment) were presented to normal intact rats. Exploratory activity measured by a digital counting device was video-taped in a 3 min duration tests. In these environments, rats had the choice to explore the right or the left aspect of the devices. Results show that in the square box, animals showed a right-biased exploration, and show no preference in the rectangular box, and left-biased exploration in the T shaped environment. Data reveal that animals show inconsistency in the lateralized behavioural response, where the geometrical characteristics of the environment are important to display some biased response.