HABITUATION AND MEMORIZATION OF SPATIAL OBJECTS CONFIGURATIONS IN MICE FROM WEANING TO ADULTHOOD

This experiment investigated the development of habituation and memori zation capacities of C57BL/6 mice. After a first session on a classic open field, four groups of subjects (3, 4, 5 and 9 weeks of age) were exposed to objects arranged in a pre-defined spatial environment durin g three exploratory sessions. Subsequently, for the test session, half of the mice was exposed to the previous situation, while the other ha lf was exposed to a novel situation with a different spatial configura tion for testing animal's abilities to detect and react to a change in their environment. Analysis showed age-related differences in behavio ural habituation patterns, Moreover, contrary to our expectancy based on previous studies, the youngest mice (3 week-old) didn't exhibit sig nificant renewal of exploration of the displaced objects during the te st session. This results indicated that the youngest mice react differ ently than the adult mice when they are confronted to a novel environm ent and especially seem enable to construct a long-lasting representat ion of their environment when this representation concerns proximal in formation. The results are discussed in relation to previous studies c onducted on the radial maze and the Morris water maze and it seems tha t the abilities of the youngest mice to construct a representation of their environment are partially dependent upon the type of information available (i.e. proximal versus distal information). (C) 1997 Elsevie r Science B.V.