A neuroscientist at the University of Colorado School of Medicine I Aurora, Colorado, was doing studies with mice. So the story goes, she was surprised to notice that the brains of some female mice who had Down Syndrome (a defect involving chromosome 21), evidenced some unexpected abnormalities. She already knew that the brains of trisomic male mice (with Down Syndrome) showed changes in their hippocampus related to protein levels. These female mice, however, showed the most serious changes in their cerebellums. Mice and rats have similarities to the human brain. Therefore, findings in these rodents often lead to potential correlations with human brains. Gardener has been quoted as saying, “If we find that males or females are differing not only in their baseline impairment, but in their response to drugs, we need to know that. We could be missing a big piece of information that could lead to better or different clinical trials.” So, if male mice had changes in their hippocampus (the brain’s search engine), and female mice had more significant changes in their cerebellum, this potentially could have implications for humans with Down Syndrome. More tomorrow.