[Comparison of the effect of sidnocarb and other psychostimulants on discrimination and prediction processes in performing conditioned food-procuring reflexes].

In an Y-shaped maze a differentiation of the positive and negative reflex signals given at random in a ratio of 50 to 50 per cent and an active selection of one of two feeding troughs, reinforced at varying frequency (0.1--0.9), were determined. Sydnocarb (10--20 mg/kg) had no influence on the realization of the food-procurement response, but improved the discrimination of the signals. Only small doses of amphetamine (0.5 mg/kg), caffein (20 mg/kg) and acephen (10 mg/kg) also improved the response to conditioned signals. Sydnocarb reduced the number of runs to a rarely reinforced feeding trough and, at the same time, stimulated an active choice of the latter. Amphetamine largely facilitated an active choice of the runs direction. Caffein displayed a tendency to reduce the number of wrong approaches. Acephen hampered an active choice of compartments in the Y-maze without impairing the ability to distinguish the frequency of the feeding troughs reinforcement.