[Genetic difference in extinction of a conditioned behavior in mice (author's transl)]

The conditioned avoidance behavior from electric shock were examined in thirty male mice of inbred JCL: ICR and DDF with a newly-designed apparatus which had a wide square open field implanted shock-electrodes in floor and a fixed arc running path way where electric shock current could be delivered or not. Data were recorded on running traces and times from the start point to the goal and analysed statistically. 1. In acquisition training, both the JCL: ICR and the DDF acquired to run the way correctly and any difference between them could not be observed. While in extinction, the JCL: ICR were more rapid than the DDF. 2. After the 2nd acquisition training, all mice were trained to run of the field where electric shocks were delivered including the way. The DDF ran into the goal correctly along the way, while the JCL: ICR did not, but ran straight into the goal. The straight-trace of the JCL: ICR could not be changed by the following acquisition. 3. After a eight weeks' pause of acquisition, all mice were tested on retention without shock delivery. The both the JCL: ICR and the DDF ran correctly along the way, and showed a full score by a few trials of aquisition-training. 4. No change in behavior between the strains was found when high voltage shock were delivered during running the way. But in evaluation trials after the delivery only the JCL: ICR showed some changes in running trace and time. 5. Arguments on the difference in the process of extinctions between the strains were proved that may be associated with the genetic difference of a inhibitory mechanism.