NEGATIVE AND POSITIVE EFFECTS OF INTRACEREBROVENTRICULAR SCOPOLAMINE ON MEMORY IN MICE UNDERGOING PASSIVE-AVOIDANCE AND ESCAPE TESTS

The effects of intracerebroventricular administration of scopolamine o n memory and learning in the conscious, freely moving mouse were evalu ated using step-down passive avoidance and water maze tests. A new tec hnique was used that allows convenient injection into the cerebral ven tricles without disturbing the animal's behavior. No significant chang es in locomotor activity were observed after low doses of scopolamine (0.1 and 1.0 mu g). However, 10 mu g produced an increase in locomotor activity, while 100 mu g caused an initial decrease followed by an in crease in activity. In the passive avoidance test, scopolamine signifi cantly impaired memory acquisition at doses higher than 1.0 mu g, cons olidation at a dose of 100 mu g, and retrieval at doses of 10 and 100 mu g. In contrast, a dose of 0.1 mu g significantly improved consolida tion and retrieval. In the water maze with a bridge, scopolamine eithe r impaired memory acquisition, consolidation, and retrieval, or had no significant effect in the dose range tested. These results suggest th at there are differences in the process of memory formation in the pas sive avoidance and escape tests.