Habits – a physiological view

Noting that habits are laid down in the brain, authors Elden and Esther Chalmers share the story of Sir John Eccles, of Australia, who some years ago was examining brain nerve cells under a powerful microscope.

Like all body cells, nerve cells have a nucleus, surrounding fluid called cytoplasm, and an outer membrane. But ex-tending from the membrane of nerve cells are many little fibres called dendrites— and one long fibber called the axon. Dendrites are like miniature receivers that pick up incoming electro-chemical messages. And the long axon is like a small transmitter that sends messages to neighbouring cells.

In between the sending axon of one nerve cell and the receiving dendrites of another cell is a tiny space called a synapse. And it was this synaptic space that Dr. Eccles was examining under the microscope when he noticed some tiny bumps on the end of the axon. He called them boutons—the French word for buttons.

We now know that those little buttons on the end of the axon secrete various chemicals. One of them, acetylcholine (ACH), bridges the synaptic space between cells, closing the gap and stimulating the next cell to send the message on down the nerve line.

“Dr. Eccles,” the Chalmerses wrote, “noticed that some sending fibres had many boutons, while others had only a few. He noticed that the sending fibres with many boutons did not require as much stimulation as those with few in order to produce the chemicals needed to send the impulse on to the next cell.

“As a true scientist, Dr. Eccles wondered why some fibres had many boutons and others only a few. He theorized that  boutons might be formed when that particular sending fibber is repeatedly stimulated. This repeated stimulation could cause more boutons to be formed, thus making it increasingly easier for messages to flow along that particular pathway.”

More recent research has confirmed what Dr. Eccles suspected. Under electron microscopes, researchers have found that repeated stimulation does indeed cause boutons to enlarge and to multiply.

“We can assume, then,” the Chalmerses add, “that any thought or action which is often repeated is actually building little boutons on the end of certain nerve fibres so that it becomes easier to repeat the same thought or action. This seems to be the way habits are formed in the nervous system. . . . The sobering thought, then, is that every thought, feeling, or act often repeated is producing physical and chemical changes in our nerve pathways, either to bless or to curse us when these changes have been strongly established.”

Do the boutons that secrete the ACH ever disappear if they are not used? Current evidence is that they do not. So if those nerve pathways are never erased, how can bad habits ever be overcome? The answer is by laying down new habit pathways in the brain that are even stronger than the old ones.

Can this really be done? Can we form good habits that are stronger than our bad ones?



What kind of habit pathways am I strengthening today by my thoughts, feelings, and actions? 


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