I was introduced to the concept many years ago when my husband's employer, Medtronic, pioneered a form of neuromodulation called deep brain stimulation to reduce the tremors of Parkinson's disease. Since then a number of other forms have been developed, some implantable devices, others used externally. Some examples include spinal cord stimulators and pain pumps.

Usually the technique is used by neurologists, neuroscientists and biomedical engineers. I am not familiar with use by naturopathy. Therapist and chiropractors some times use external TENS units.

Here are a couple of articles I found.

https://www.neuromodulation.com/neuromodulation-defined
https://www.neuromodulation.com/neuromodulation-defined

Can you explain more about what is meant by "coding"?

Sue