The cognitive testing rats were regularly subjected to an activity called “forced swimming”, during which they were repeatedly made to swim and look for a landing platform on which to rest (the Morris Water Maze). This was also described in April's post. Rodents do not like water at all, everytime they were removed from their cage, they knew that they were going swimming. As a result, these rats are were in a hypervigilant state and under a lot of stress.
When these cognitive rats were mistakenly put with the breeding rats, it was discovered that the breeding mothers began to display hypervigilant behaviour. These hypervigilant “bad mothers” licked their offspring less and offered less tactile stimulation than “good mothers” who would lick and groom their pups and give them room to suckle.
This resulted in the offspring also displaying hypervigilant behaviour, lower pain tolerance and a higher tendency to go into chronic pain states.
So we learnt:
- Exposing mothers to hypervigilant individual (source animal—primary stress) imprinted hypervigilance onto them.
- Pre or postnatal secondary traumatic stress promotes hypervigilant state in offspring.
Given that the gestational period of rats is 21-24 days, Dr. Durham was able to track this hypervigilant state, and he found that this hypervigilant state was passed on to the next three or four generations…gives the phrase “sins of the forefathers” a new meaning…