Mice of the ddN strain with high training scores were selected for the study of genetic improvement through avoidance training. Mice used were from 7th to 9th generations. Colcemid and lidocaine, which are known to temporarily disrupt microtubules and impede axonal flow. In the present study the effect of these two drugs on learning behavior in mice were studied. Animals were injected with colcemid and lidocaine either intraperitoneally (50 μg in 0.5 ml) or intracerebrally (10 μg in 10 μl) on both sides of the frontal lobe to a depth of 3 mm. Injections were performed either before or after training sessions. Autoradiographic analysis confirmed that (3)H-colcemid injected intraperitoneally had been incorporated into the peripheral regions of the cerebral ventricles and had not extended into adjacent regions in less than one hour. Similally, (3)H-colcemid injected intracerebrally was shown to be incorporated into ventricle regions and to have extended into adjacent regions. Colcemid and lidocaine did not produce any remarkable change in open field activity of the mice.
Intraperitoneal administration of colcemid and lidocaine did not affect either acquisition or retention of avoidance behavior. Intracerebral administraion of colcemid interfered only slightly with the acquisition and retention of avoidance behavior, but produced a profound loss of memory acquired previously. Intracerebral injection of lidocaine before or after training sessions did not affect either acquisition or retention of avoidance behaviour.