Impaired learning has been shown as a consequence of isolation-rearing
in a variety of paradigms. However, there are situations in which lea
rning in isolation-reared rats is enhanced or unimpaired compared to s
ocially reared rats. The present experiments investigated the effects
of isolation rearing on place navigation in the Morris water maze. Two
complementary paradigms were studied: isolation and socially reared r
ats were exposed to the water maze either without drug pretreatment or
following systemic administration of scopolamine. Two conditions were
examined: place learning and reversal learning. Male Lister hooded ra
ts were either housed singly (isolation reared) or in groups of four (
social reared) from weaning at 21 days of age. Six weeks later place l
earning and reversal learning were determined using the Morris water m
aze. The time taken to locate the submerged island (escape latency) wa
s used as the measure of learning ability. The results showed that pla
ce learning, and reversal learning were enhanced in isolation reared r
ats compared to socially reared controls. Pretreatment with scopolamin
e (0.3 and 0.5 mg/kg, i.p.) produced a dose-related cognitive deficit
as shown by an increase in the escape latency. Scopolamine (0.3 mg/kg)
impaired both place and reversal learning but this was less pronounce
d in isolation compared to socially-reared rats. These results suggest
that rearing in isolation may enhance spatial learning though central
cholinergic mechanisms.