Bj. Hoplight et al., Effects of neocortical ectopias and environmental enrichment on Hebb-Williams maze learning in BXSB mice, NEUROBIOL L, 76(1), 2001, pp. 33-45
Approximately 40-60% of BXSB mice have neocortical ectopias, a developmenta
l anomaly characterized by migration of neurons into the neuron-sparse laye
r I of cortex. Previous studies have shown that ectopic BXSB mice have supe
rior reference, but inferior working, memory on spatial tasks. Female BXSB
mice were housed either in an enriched environment or in standard cages at
weaning. Subsequently, these animals were tested on four of the Hebb-Willia
ms mazes in a water-based version of this maze. Theoretically, two of the m
aze configurations placed greater emphasis on reference memory to find the
goal, whereas the other two favored working memory. Ectopics reared in stan
dard housing conditions were better than nonectopics on mazes that favored
the use of reference memory, but poorer on mazes that favored working memor
y. In contrast, subjects raised in the enriched environment showed no ectop
ia differences. A comparison of enriched and standard housing conditions fo
und that the enriched animals had better reference memory but poorer workin
g memory. The latter effect may be because the enriched environment, althou
gh more stimulating, did not change in time or space; and other researchers
have shown that daily replacement of stimuli in complex environments is co
rrelated with better working memory, (C) 2001 Academic Press.