Retention of memory traces in rats subjected to 10 minutes of clinical death.

Studies of the effects of 10-min clinical death in mongrel rats, induced by complete circulatory arrest, on the mechanisms of memory, showed that the content of already formed memories ("what to do?"), i.e., the structure of a food-procuring habit, motivational activity, and the level of organization of behavior, was completely retained 12 days after resuscitation regardless of how many traces were formed before the experimental procedure. Transient changes seen after clinical death mainly affected the process of performing the habit ("how to do it?"): there was a decrease in the ability to work, along with degradation of performance parameters such as readiness, mobilization activity, and the stability with which memory traces were performed. The rate of recovery of these aspects depended on the initial level of conditioned reflex activity in the rats: the higher this level, the more rapidly the performance parameters returned to the baseline level. It is suggested that these disturbances in the process of reproduction were non-specific in nature and could be due to the post-operative hyperexcitability of the animals.