Effects of post-weaning environment and apparatus dimension on spontaneous alternation as a function of phenotype in "dwarf" mice.

The spontaneous alternations of "dwarf" mice estimated in a Y maze proportioned to the size of control mice demonstrated the necessity of reducing the size of the apparatus for testing the "dwarf" mice. Tested in a maze of reduced dimension, the "dwarf" mice showed a significant deficit in this task but only in a T shaped maze, and not in a Y shaped maze. For one month after weaning, "dwarf" and control mice were reared in either an enriched or an impoverished environment. These rearing conditions did not modify the spontaneous alternation of control mice whether estimated in a T or a Y maze, but they significantly altered the behavior of "dwarf" mice, yet only when evaluated in a T maze: "isolated" "dwarf" mice alternating less than "enriched" "dwarf" mice. It is suggested that this behavioral profile displayed by "dwarf" mice in spontaneous alternation might be explained by a deficit in perceiving, integrating and/or utilizing complex spatial information.