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Abstract:
A series of studies suggested that frequencies of maternal
grooming and arch-back nursing can influence a number of
neurochemical measures of the stress response system, which in
turn, can mediate stress induced and age-related cognitive
difference (Meaney et al 97). We directly examine the effect of
maternal behavior on the early cognitive development in rats by
using a modified and completely video-taped neonatal handling
procedure (split litter design), a moving platform version of the
Morris Water Task (Whishaw 85), and a one-trial learning measure.
The split-litter design allows us to rule out potential
contribution of genetic influence on any observed differences in
the handled and non-handled offsprings. The moving platform version
of the water task and the choice of one-trial learning provides us
a measure for the capacity for rapid information acquisition and
for spatial episodic memory. We measured three categories of
maternal behaviors in 5 sec video clips for the first 5 min
post-handling period from post-natal day one through day fourteen,
and we correlated the mean frequencies of these maternal behaviors
individually to the corresponding offspring learning measures. The
three categories were the nurturing (pup grooming, nursing,
transferring to nest), the aversive (stepping on pups,
carrying/throwing pups), and the neglectful (dose plowing, sniffing
cages, self-grooming). To determine the influence of maternal
reliability on offspring cognitive development, we correlated the
variance of each maternal measure over multiple post-natal days
with offsprings spatial learning capacity.
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