TABLE 1.

Chronological ages and numbers of mice used.

Age cohort (months)	Group*	Number of mice included	Excluded (details)
3	Behavioral test battery	24	0
	Water maze retention	30	0
6	Behavioral test battery	23	1 (torticollis)
	Water maze retention	20	0
12	Behavioral test battery	24	0
	Water maze retention	18	2 (unknown)
18	Behavioral test battery	24	1 (cataract)
	Water maze retention	18	2 (cataract/unknown)
22	Behavioral test battery	22	2 (unknown)
	Water maze retention	18	2 (cataract/unknown)

*Mice in the water maze retention group were divided into two subgroups of retention intervals for each age cohort: one subgroup was tested for retention of platform location 10 days after the completion of acquisition training, and the other subgroup was tested for retention 30 days after acquisition training.