Adult susceptibility induced by preweaning shifts of Zeitgeber in rats (II).

The exposure of young rats to atypical time indicators (Zeitgeber) between birth and weaning modifies the reactivity of adult rats. Rats treated in this way early in life are isolated at day 130 for 14 days and then put through a distributed trials learning in a Y maze. Day after day performances show a deficit of this group compared to controls in the evolution of daily success scores as well as in the number of negative reinforcements received. When the rats are left for 30 min or more in the test room before the beginning of the daily trials, the difference between control and experimental groups decreases, though it does not completely disappear. It is concluded, therefore, that the early alteration of the Zeitgeber modifies the later reactivity of the adult rat and affects its capacity to face a learning situation.