In your physical brain you have about a hundred billion neurons. Those neurons have about 1,000+ synapses each, which means you have somewhere around a 100 trillion connections in your brain. There are two types of neurons. There are axons and dendrites. Axons are the little nerves which send messages around inside of the brain. On average an axon is about one micron thick.
Brain researchers using CAT scans have seen that the neuron pathways that we use highly can be as much as three to six microns in thickness—instead of only one micron. We use all of our brain, but there are certain pathways we use more than others. Habits would be an example of a highly travelled pathway. Those that are highly trafficked can become up to six microns in thickness. That’s a huge difference! The more you use a specific train of thought, the more you do a certain behavioral pattern, the more you focus on specific aspects of your life, the larger the axons of that part of the brain grow.
But it’s also true that when axons quit being used as much, they shrink and become smaller. It’s rather like a muscle. Without use it will begin to atrophy and it gets smaller. And so it is with the neurons in your brain.
A nerve that gets fired frequently increases in size because it’s a pipeline of energy. Think about it that way. As the quantity of energy required to flow through the pipeline increases, you need a bigger pipe, so the pipe must expand. The more energy you give to your focus and your goals, the more that you energize and expand the nerves.