The dye studies show that ultimately its about applying focus until other areas of the brain become starved as a result of over prioritizing the area associated with the focus.
Like you focus on the sound of a stream and your brain processes that sound as if it’s the most important thing in the world because you’ve given it that designation. Everything else gets put on standby, even basic processes like the sense of self, which being a fairly recent evolutionary development is one of the first things to be powered down.
Also meditation tends to traditionally occur in sparse boring settings. Putting yourself in a state of sensory deprivation where in you start to get clear data from your body, for example being able to hear your heartbeat due to near silence, produces a situation where biofeedback training becomes possible, and since this possibility emerges in that sensory deprived state (the isolated monastery) you are able to use this as “something to do” and you can train at it constantly while sitting there.
This sort of biofeedback training can be achieved by other means with a heartbeat monitor, but body temp control (another interesting display of meditative “powers”) is slightly trickier. It’s a well known fact that thinking of running vividly enough causes micro-tremors in the muscles associated with running. So I could easily picture something similar being done with convincing yourself you are cold, and thus trick your body into requesting heating measures. I suspect this would be far easier to do if you’re in the starved state mentioned above since the brain would be less able to process conflicting data (the actual temperature readings).
In short meditation is not magical, its not even particularly special, its just another brain state and I’m personally tired of it being the intellectually fashionable way to indulge in golly gee mysticism. I’m tired of it being the atheist’s kosher religion