Neural Plasticity and Feminine Sexual Behavior in the Rat

Abstract

Female mating behavior in the rat is normally under the control of estrogen and progesterone. These ovarian hormones act upon the brain to bring about sexual receptivity. One concept often used to explain how these hormones facilitate mating behavior suggests that lordosis is under some form of tonic neural inhibition and that estrogen and progesterone decrease this inhibition. Since an inhibitory concept is only one of several alternative explanations, and since there is considerable evidence that contradicts an inhibition hypothesis in its general form, it is instructive to review the “crucial” studies for this concept before trying to outline alternative interpretations and hypotheses. In this endeavor I will restrict my comments to the laboratory rat.

Long ago in a land called Science there lived a clever toymaker who was called Able. Now Able had many customers and, therefore, he had to work long hours to finish all the toys. So one day he decided to build a machine to help with the work. After many months, clever Able finally completed a robot, and it came to pass that this child of Abie’s did many things for him. Able loved his robot as a parent would love a child and Able gave the robot a name: Hypothesis. Hypothesis kept Abie’s shop tidy and neat. Able also found that if he gave Hypothesis the parts to a new toy, Hypothesis could put them together. Because Hypothesis was a capable robot, Able gained a certain noteriety in the land, and this pleased Able.

But times in the land of Science change and with this change came the need for new and different toys. Clever Able adapted easily to this change, going from wooden dolls and mechanical toys to more elaborate electronic gadgets and toys involving mathematics and chemistry. However, as so often happens to busy toymakers, Able did not take the time to make necessary changes in Hypothesis and so the robot just plodded along putting things together in the only way he could. The result was that, although the toys which Able put together worked very well, the ones his Hypothesis assembled had little resemblance to Able’s work. But Able loved Hypothesis and to change him would be like destroying a true friend, like destroying a part of himself. Able had not the heart to give up his friend even though the wooden stereoscopes Hypothesis put inside the toy televisions looked silly. And so what if the electronic tennis game had wooden wheels and airplane wings. If this was the way Hypothesis was going to put new parts together, then Able felt obliged to overlook his friend’s shortcomings.

In time, however, Able did change his robot’s name to commemorate their long career together and from that time on Hypothesis was known as Postulate. His toys? Oh, Postulate continued to make his strange toys and people bought them because they knew that Able was a good toymaker. Besides, it is easier to buy a ready made toy than to make one.

Where is Postulate now? After Able died, no one paid much attention to his Postulate and in the land of Science, Postulates cannot live very long without a lot of love. I have heard, though, there is a new toy-maker now and they say he has a bionic assistant working for him.

From an unwritten work “Robots I Have Known and Loved”

by L. Clemens

This research was supported by PHS Grant No. HDO6760.