Happiness is probably the goal that everyone of us is pursuing. We often think that if we can make the right choice, we will be happy forever. It seems that there is such a road that will lead us to find a relaxed and contented life full of laughter. However, even the happiest experiences are often fleeting, and people are getting bored and looking for fresh excitement. As a neuroscientist, I can't help but doubt that the fleeting pleasure is inevitable, which even reveals an established way for the brain to work. Only by understanding this can we find a way to deal with it.
Our brains are working all the time, so that it is difficult for us to observe and think about how they work without participation. The basic job of the brain is to perceive and then analyze and evaluate. Based on these assessments, we can take action. This work is done by neurons in the nervous system. They detect and express stimulus signals from the outside world (and the inside world), and then take appropriate actions to respond to them. When you act, neurons send out signals, muscles begin to contract, and the action is completed.
How do the neurons that make up the brain detect and analyze what is happening in the world? The simple answer is that they depend on signal translation first. Eyes, ears, nose, tongue and skin, these body parts are our sensory organs. They have sensory receptor cells that receive information from the outside world. Tiny protein molecules are located on the membranes of these cells, which transform external physical stimuli (light, sound, chemicals and heat) into the language of the brain: electrical signals called action potentials. Transduction proteins connect tiny channels or ion channels for charged particles such as sodium and potassium to enter and leave cells. The movement of ions generates electrical signals, and each electrical signal propagates along nerve cells through other protein, eventually leading to the release of chemical neurotransmitters. The next neuron receives neurotransmitters through its receptor proteins, and these receptors also contain ion channels. Our perception ability mainly comes from our ion channel proteins.
Interestingly, almost all of these protein will respond to the change of stimulus, but if they are exposed to continuous mild or moderate stimulus for a long time, many of them will automatically shut down and cut off the ion circulation. We call this process adaptation (or desensitization and inactivation, depending on its physical basis). It leads to familiar sensory experiences.