How does the practitioner facilitate the brain to make the corrections? 

No practitioner is capable of making any correction by ‘doing’ something to modulate a response.  That is a fallacy. The ‘doing’ will only be achieved if the brain will acknowledge the incongruence via the post central gyrus, and therefore is responsible for the outcome.
NIS facilitates the post central gyrus (the message and receiving centre of the brain) to acknowledge the incongruence so dysfunction can now be addressed/corrected by the brain. This restores appropriate control of the sensory-motor loop, giving back control to the testing muscle. 

Why we use the Post Central Gyrus
- Primary sensory area of the brain
- Allows stereognosis (to recognise form & touch)
- Collective stimulation of this area reinforces recognition by both hemispheres of the respective anatomical contacts being held at the time.

The neuro-anatomy behind the application of hemispheric integration
How is dysfunction addressed?
NIS facilitates the post central gyrus (the message sending and receiving centre of the brain) to acknowledge the incongruence so dysfunction can now be addressed/corrected by the brain. This restores appropriate control of the sensory-motor loop, giving back control to the testing muscle. In doing that, normal neurological activity and homeostatic balance is achieved.
In other words….. once the brain acknowledges the dysfunction, it (the brain) will in its infinite wisdom correct it with absolute accuracy. 
No practitioner is capable of making any correction by ‘doing’ something to modulate a response.  That is a fallacy.  The ‘doing’ will only be achieved if the brain will acknowledge the incongruence via the post central gyrus, and therefore is responsible for the outcome.
Find out more about Muscle Testing & NIS

How does the brain acknowledge?
This integrative or acknowledgement process involves the practitioner gently ’tapping’ a very precise area of the cranium. Although on the face of it, this may seem too simple and esoteric to be valid, that is most definitely not the case.  With NIS we are working with a very defined area of neuro-anatomy.

Firstly, when the skin is touched, merkels tactile disks associated with slow adapting receptors are stimulated. These mediate light touch sensations which project centrally via the spino-thalamic tracts and the dorsal column medial lemniscus (DCML) pathway. This neuro-pathway is directly associated with the Post Central Gyrus. Secondly, when the skin is touched (i.e.: on the patients cranium) there are receptors stimulated that project sensation via the DCML to the post-central gyrus.  Thirdly, pacinian corpuscles found in the dermis of the skin respond to contact and pressure.  Again this sensation is mediated via the DCML to the post central gyrus. The key function of the DCML is to recognise form by touch (sterognosis) and recognise the position of body parts in space (statognosis). These both relate to the Post Central Gyrus, making it the message and dispatch centre of the brain.

Stereognosis & the Post Central Gyrus  
Close your eyes & have someone touch just one hair on your head, you will be able to tell them exactly where they touched.  

That is your Post Central Gyrus relaying the message. It allows you to relate exactly to that sensation and its location.

The same principle applies in NIS treatment....it is the Post Central Gyrus that knows exactly which contacts (and about their relationship to each other) the practitioner is holding.