Even foster-mother rats which had been given the young of others to look after performed better than the rodents that had not mated or had any contact with offspring. The team believe that the hormones produced during pregnancy, or the experience of giving birth and suckling pups, may cause physical changes in the brain that make it easier for the female rat to remember where things are. As a result, the mother rat is better able to cope with the demands of rearing her young such as remembering nest sites and food and water stores. Rats are different to humans, of course, but as mammals we quite clearly share many brain functions. Previous research has already shown that raised hormone levels in female rats preparing to mate increase the concentration of neural connections in the hippocampus, a primitive part of the brain thought to be linked to memory.
Pregnancy raises levels of the hormones, oestradiol and progesterone, for an even longer period.
The stimulation that comes from suckling in particular probably reorganises connections in a part of the brain called the hypothalamus. The BBC is not responsible for the content of external internet sites.