Thousands of years ago, yogis taught that for each human being to evolve their behaviour, intelligence and the health of the body, they must learn how to shift the functions of everyday life from lower, to higher.
We can now name this process as shifting the functioning from the limbic (primitive, emotional, reptilian) brain - to the higher brain, the cerebral cortex, in a process known as telencephalisation. Yogis taught that telencephalisation can be achieved simply, in 8 - 12 minutes and that this is part of the meditative process which leads into the state of meditation. Navel-gazing for example, does this.
Essentially the technique is to put the breath under surveillance whilst lying down (or sitting) completely still.
During that 8 - 12 minutes the awareness can be in the chest, in the nostrils, the navel, abdomen, brain, the heart chakra, in any one place. The breath will express in many different ways as it goes through its process. Some of the breathing expressions you can expect to experience temporarily are : deep breathing, shallow, rhythmic, arhythmic and erratic, gasping, etc, etc, until, eventually, the breath settles into a soothing rhythm.
When the rhythmic breath is established in an unchanging soothing rhythm, the process of telencephalisation has been completed. Functioning is now coming from the higher brain.
Remaining focused, simply observing in this way, is known as mindfulness meditation.
In recent decades scientists have explored and experimented re the effects of meditation on the brain, here is one article, in part:
"A number of studies have linked meditation practice to differences in cortical thickness or density of gray matter. One of the most well-known studies to demonstrate this was led by Sara Lazar, from Harvard University, in 2000. Richard Davidson, a neuroscientist at the University of Wisconsin, has led experiments in cooperation with the Dalai Lama on effects of meditation on the brain. His results suggest that long-term, or short-term practice of meditation results in different levels of activity in brain regions associated with such qualities as attention, anxiety, depression, fear, anger, the ability of the body to heal itself, and so on. These functional changes may be caused by changes in the physical structure of the brain."
Read whole article, at: https://en.wikipedia.org/wiki/Neuroplasticity