A simple way to understand the complex human brain

Megan Gahart, 10, a fifth-grader at Butterfield School in Libertyville asked, "How do brains work?"

Dr. Martha Constantine-Paton, professor of biology and brain and cognitive sciences at the McGovern Institute for Brain Research at MIT, studies brain development and the brain's pathways that allow us to see and hear.

"The brain is the central command station of your entire body. The brain and the spinal cord together constitute your central nervous system, or CNS," Constantine-Paton said.

Constantine-Paton reports that more than 50,000 scientists all over the world are working in the field called neuroscience to discover more information on how the brain works.

The human body is made up of many different cells with very different functions. The CNS contains cells called neurons that are specially designed to communicate with all of the cells in your body. Some can also gather information from the outside world.

"A set of neurons in your eye will receive a signal from light-detecting cells, also in your eye, that registers an object, such as a dog, in your visual field. The light becomes chemical signals that are transformed into a pattern of small, short, electrical impulses. These impulses travel to your brain very quickly through the long extensions of neurons called axons that extend from the eye and thread into your brain," she said.

The complicated process continues as the chemicals extend to different parts of the brain. Constantine-Paton explained, "The pattern of nerve impulses gets distributed to several 'maps' of your visual world in the visual areas of your cerebral cortex -- a layered blanket of neurons that covers your brain. Think of this blanket as a patchwork quilt. Each of the patches has a different function. The big cerebral blanket is folded together into valleys and hills so that it all fits inside your head.

"Each part of the brain has its job to do so you can understand the world around you. For example, the information coming through your visual pathway may register a black object moving in front of you. At the same time the neuron pathway from your ear will register as a series of impulses the sound of the dog barking," she said.

When those chemical impulses meet at the front part of your brain, the frontal cortex, your brain understands that a dog is barking. Next, the signals are matched with information from neuron networks that retrieve memory.

"If you have been bitten by a dog, neurons will relay memories of fear and send impulses that will contract your muscles and move your limbs to run away," Constantine-Paton said. "But suppose your neuron networks encoding memory tell your frontal cortex that you know this dog, maybe it is your own dog, and you remember that this barking means that she wants to play. Then your frontal cortex registers excitement or happiness and sends impulses to your muscles that cause you to run toward the dog and hug her."

This is a very simple description of a very complex process. But understanding the way the brain works will help researchers to unlock bigger issues, like why people feel a certain way about themselves.

"Many scientists would like to understand the impulse patterns and neuron pathways that cause each set of these chemical information transmitters to be released so that medical doctors can treat an unhappy person so they can feel happy, or perhaps help an easily frightened person to feel more secure," Constantine-Paton said. "Maybe in 50 to 100 years we neuroscientists will get the more complete picture. Once we fully understand it we hope our brains will seem much simpler. What do you think? It is your brain thinking."

For more information

The Cook Memorial Library in Libertyville suggests these book titles on the brain:

• "Brain Power- The Brain, Nervous System, and Senses," by Dr. Patricia Macnair

• "Think, Think, Think -- Learning About Your Brain," by Pamela Hill Nettleton

• "Brain-Injury, Illness and Health," by Steve Parker

• "It's All in Your Head -- A Guide to Your Brilliant Brain," by Sylvia Funston and Jay Ingram

• "Thinking and Feeling," by Jillain Powell