Male and Female Brains

Male Brain

Female brain Comic......Laught it out!!!!!!

Sex differences and the brain.

What does it matter, you say? I think it does. Through such knowledge we will eventually be better able to understand the basis for behaviors that many now perceive as entirely rooted in social custom or familial history. From that understanding, we will gain the acceptance, patience, and respect so vital to all human endeavor.

Interestingly, people who see a human brain for the first time often ask, "Is it male or female?" Yet, for many millennia no one, even scientists, thought about sex-related differences and similarities in the human brain. A brain was just a brain. Now hardly a year goes by that we don't read authoritative studies showing these differences. I was taken aback just a few months ago when, at a Ph.D. examination dealing with Magnetic Resonance Imaging of human brains, the student reported having pooled the data from both sexes. Even if the intent was not to explore male-female differences, one can hardly expect to make accurate interpretations from such mixed data.

Obviously, no single factor accounts for the gender-related differences we are finding. We are slowly, one by one, unraveling the various integrative factors involved in this mystery. A basic question being asked is whether the differences between male and female brains outweigh the similarities or vice versa. Some researchers report finding more differences within the sexes than between the sexes. Please understand that the objective of my talk is not to discuss whether the brain of one sex is superior to the brain of the other but to explore the significance of the differences we are discovering in the brains of males and females. As you might imagine, to conduct these studies, we need brain samples so that we can make our comparisons. So far, no live human beings, males or females, have been willing to give us their brain tissue to use in our experiments. But all is not lost: The rat brain, oddly enough, has the basic components and major structures in its little pecan-size brain that we humans have in our large cantaloupe-size brain. In general terms, what we have learned about the anatomy of the rat brain has later been replicated by studies in higher mammals including humans. What is particularly important, of course, is that using the laboratory rat allows us to control many variables--the sex, the age, the living conditions, the diet, the water intake, the environment, and so forth, thus assuring clear comparisons.

To appreciate the work we do, let me take a moment to give you some fundamentals of the brain's anatomy. In the embryo our nervous system starts as a simple tube, the head end forming the brain and the remainder forming the spinal cord. The brain is divided into three parts: the hind brain, midbrain and forebrain. Our interest is primarily in the forebrain, which expands tremendously over the course of its development to form about 85% of our total brain, called the cerebral hemispheres. These two large hemispheres are familiar to anyone who has seen a picture of the brain The outer layers of the cerebral hemispheres are called the cerebral cortex. (Cortex means bark.) With the use of a light microscope we can easily measure the thickness of this cortex in the rat because it is smooth and does not have folds as do more highly evolved brains.

Factors affecting cortical thickness are the main interest in our gender studies because the cerebral cortex is the most highly evolved part of the brain and deals with higher cognitive processing. The cerebral cortex, like other parts of the brain, consists of nerve cells with branches and functional connections called synapses; glial cells, the metabolic and structural support cells for the nerve cells; and blood vessels. Cortical thickness is a key factor; it gives us an overall indication of what is happening collectively to these structures within the cortex.