The human brain contains some 10,000 - 15,000 million nerve cells, called neurons, and one million billion synapses (the connections between nerve cells). But the way in which the brain functions is still, to an extent, a medical mystery, so we can't say with certainty how much the physical differences between people's brains affect or contribute to their behaviour.
The brain – where women are different
Women have slightly smaller brains than men (they weigh about 4oz/100g less) but, as we know, size isn't everything. Elephants, for instance, have much larger brains than humans, but nobody believes they have more intellect. And though women's brains are smaller than men's, they both have a very similar ratio of brain weight to body weight.
Women also have 4 per cent fewer brain cells than men, but this doesn't mean they use them less! There are other male/female differences too!
The frontal lobe of the brain plays a major part in making judgements, planning future actions, and in language. Women have far more cells here than men.
The hemispheres
It is believed that these two halves of the brain probably work differently. The left side helps us think analytically, while the right side helps us look at things as a whole, involving value judgements and emotion. Men are more likely to be "left-brain dominant" while women are thought to use both hemispheres more equally.
The corpus callosum transfers information between both halves of the brain. Women have a bigger corpus callosum than men, which may account for the fact that women score better on tests of thought fluency and speech.
The limbic system affects our emotions and is, on the whole, bigger in women. Together with a female brain's greater ability to transfer information between its two sides, these facts may help account for women's greater emotional sensitivity. The bigger limbic system may also mean that women feel negative emotions more sharply, opening them up to a greater risk of depression.
Grey matter and white matter
Processing information goes on in the grey matter, while white matter connects the different parts of our brain, enabling us to carry out various tasks. Women tend to have far more white matter than men, while men are endowed with far more grey matter. Could any or all of these differences above be an explanation for the popular theory that women are better at "multitasking" than men?
The hypothalamus controls the endocrine system that produces many of the hormones in the body. The functions it regulates include sexual function, sleep, water content, and body temperature. In men the hypothalamus is about twice as big and contains twice as many cells as it does in women.
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Excerpted from Women's Health For Life, copyright 2009 Donnica Moore, MD and DK Publishing. Used by permission of DK Publishing.All Rights Reserved. No part of this excerpt may be reproduced except with permission in writing from the publisher.
