There is a difference between men and women, and it isnâ€™t just gender. Several brain regions also differ. A womanâ€™s brain is always active, while a manâ€™s brain needs stimulation.
Shinji Tsukahara and his colleagues at Saitama University near Tokyo, Japan, presented their findings at the recent Society of Neuroscience meeting in Washington, D.C. They reported that several brain regions linked to sexual behavior have been found to differ between the sexes in both humans and other mammals.
To find out whether a region known to be bigger in males was altered by sex, the researchers compared the brains of male rats that had never had sexÂ before with their more experienced counterparts. They found that the number of spiny structures located at the neuronal synapses was significantly lower in rats that had copulated.
Tsukahara, believes that the presence of the female leads to the hormonal changes that causes a decrease in spines, as well as sensory inputs from the penis. These regions may serve as â€œa one-way road to learn how to mate,â€ he suggested, and that once this region has been activated it may be lost, as it is no longer needed. Sexual behavior in female rats is also affected by the spines.
In a different study, University of California at Los Angeles researchers Paul Micevych and his colleagues investigated the effect on the brain of the female rat’s sexual cycle – characterized by an increase in oestradiol production every four days. In order to control the cycle, the female rats’ ovaries were removed and the rats were injected with oestradiol.
They found that the number of spines, and sexual behavior, found in the hypothalamic arcuate nucleus, an area of the brain correlated with the amount of oestradiol injected into the rats. Thosegiven the largest doses of oestradiol had more spines, and responded sexually to the male rats 80% of the time. Those who received the smallest doses had fewer spines, and only responded to 10 % of the males’ advances.
When a drug to block the formation of spines in a separate group of female rats was used, the female rats were less receptive to sexual advances than those in a control group. This research, published in the Journal of Neuroscience, would suggest that instigating sexual behavior requires the growth of new spines.
The UC group of researchers also were able to identify the receptor through which oestradiol was having its effect. â€œIn principle,â€ he says, â€œa drug developed to target this receptor could stimulate the growth of new spines, with possible implications for altering libido in humans.â€
Neuroscientist Stuart Tobet from Colorado State University in Fort Collins, says the studies provide a â€œglimpse into how changes in the structure of spines contribute to the ability to display sexual behaviors in rats, and perhaps by extrapolation, to other mammals including humans.â€
About the author:
Ron White is a two-time U.S.A. Memory Champion and memory training expert. As a memory keynote speaker he travels the world to speak before large groups or small company seminars, demonstrating his memory skills and teaching others how to improve their memory, and how important a good memory is in all phases of your life. His CDs and memory products are also available online at BrainAthlete.com.
New Scientist – Sex on the brain is different for males and females: http://www.newscientist.com/article/mg21228423.700-sex-on-the-brain-is-different-for-males-and-females.html
Journal of Neuroscience – Membrane-Initiated Estradiol Signaling Induces Spinogenesis Required for Female Sexual Receptivity: http://www.jneurosci.org/content/31/48/17583