MONICA K. HURDAL Frequently Asked Questions: Brain Facts Phone: +1 850 644-7378 Fax: +1 850 644-4053 E-mail: mhurdal@math.fsu.edu

Often I get asked questions about the brain, such as how big is it or how many neurons are there. So I decided to compile a list of Brain Facts. Some of this information may be out of date as new research becomes available, but I've always include a reference from where I got the information. If anyone has other Brain Facts which I could add, I would be happy to do so, as long as you provide a reference. This list is for information only, and I take no responsibility for its accuracy or usefulness.

• The human brain weighs about 1.4 kg and contains about 100 billion neurons (Fischbach, 1992).
• The broad folds of the highly convoluted surface of the grey matter is known as the cerebral cortex. The cerebral cortex is about 2mm thick and has a surface area of about 2000 square cm. This is about the size of 3.5 sheets of (8.5 x 11 inch) paper. There are approximately 10,000 neurons under every square millimetre (Regan, 1989).
• There are at least six neuron layers of different sizes and shapes (England and Wakely, 1991).
• Brain diseases and disorders affect an estimated 50 million Americans. Schizophrenia affects an estimated 1 percent of all people between the ages of 18 and 25 (see Banking on Brainpower, spring 1998).
• Ataxia means clumsiness, or loss of coordination. It is a sympton and not a specific disease (The National Ataxia Foundatation).
• The Brain Myth! Ever hear that you only use 10% of your brain? This is a myth - you use all of your brain! See some of the reasons behind this myth.
• Check out these Brain Facts and Figures.
• Brain Basics and Disorders from the National Institutes of Health.
• Brain Anatomy Tutorials.

References

• England, M. A. and Wakely, J. (1991), A Colour Atlas of the Brain and Spinal Cord. An Introduction to Normal Neuroanatomy, Wolfe Publishing Ltd., London.
• Fischbach, G. D. (1992), Mind and brain, Scientific American 267, 24--33.
• Regan, D. (1989), Human Brain Electrophysiology. Evoked Potentials and Evoked Magnetic Fields in Science and Medicine, Elsevier, New York.