EARLY BEHAVIORAL-DEVELOPMENT OF MICE IS AFFECTED BY STAGGERER MUTATION AS SOON AS POSTNATAL DAY-3

Staggerer is a neurological mutation of mice that affects the developm ent of the central nervous system and causes abnormal behaviors. The s taggerer cerebellum is already abnormal at birth and as the animal gro ws up there is a progressive loss of granule cells which have all disa ppeared by day 28. The earliest behavioral disturbance observed is a m otor deficiency which occurs between 10 and 15 days - i.e. several day s later than the appearance of the cortical abnormalities. To show tha t staggerer mutant mice also differ from normal mice in behavioral asp ects before the age of 10 days, 28 staggerer pups and 246 normal pups aged from 1 to 9 days underwent different motor tests. In addition, th e number of ultrasounds emitted during 40 s was recorded, and the anim als were weighed every day. Differences between staggerer and normal m ice were found as early as 3 days: staggerers were less efficient in m otor tasks and they weighed less than normal mice. Staggerers also dif fered from normal mice in ultrasound production.