Activation is our brain cells or nerves working together, or communicating with each other to create a thought or action. The body does this through cells called neurons, that send electrical signals down the axon. The terminal may connect to a number of things, like possibly a dendrite from another neuron. It releases a chemical (neurotransmitter) which has the ability to excite what is connected to it. We activate the brain whenever we use it, and especially when we use it to learn or do something new or difficult.https://ucsdnews.ucsd.edu/pressrelease/why_are_neuron_axons_long_and_spindly
Use it or lose it. Your cells need to fire at each other, to communicate, and connect one to another. Cells have the potential to cause action in the cells they communicate with. This keeps them alive. Without the energy they get from being used, cells die. (It requires energy to keep the nerve cell alive and to build neurotransmitters.)
In a very basic analogy, Some neurons tell your body to do something, while some tell them to stop doing something. If your action neurons die, then your brain might lose some of its control over your body. Lack of activation is common in movement disorders such as Parkinsons.
Receptor-based therapy is helpful for teaching action neurons to do what they have to do, when there are fewer of them than we’d like. In reality, we need to ensure that the brain’s connections are such that a person doesn’t feel driven to perform self-stimulating types of behaviors in order to keep certain parts of the brain from dying. This is seen commonly with childhood developmental disorders such as the autism spectrum, but the same networks of neurons may be struggling to receive activation in adults as well. By changing and strengthening certain connections, we can train our brain to balance those connections and more effectively activate itself to do what it needs to do.