Tony Buzan in his book Make the Most of Your Mind relates the story of an Indian Yogi, Swami Rama, who in a lab experiment was able to willfully change the temperature of a spot on his right hand. What specific yogic/tantra practice would help do this feat? Here is the relevant excerpt from this book
Bodily functions can be brought under control, under highest form of Yogic techniques.
The following is an excerpt from the famous book by Dr. Paul Brunton "A search in Secret India".
The author met an yoga expert by name Brama in Madras (now Chennai). Brama demonstrates that heart beat/pulse can be stopped.
"You can control the working of your heart?" I exclaim in surprise.
"My self-acting organs, the heart, the stomach and the kidney, have been brought to some degree of obedience," he answers quietly, without a trace of boastfulness.
"How do you do that?"
"One gains the power by practising certain combinations of posture, breathing and will-power exercises. Of course, they belong to the advanced degrees of Yoga. They are so difficult that few persons can ever do them. Through these practices I have conquered somewhat the muscles which work the heart; and through the heart muscles, I have been able to go on and conquer the other organs."
"This is indeed extraordinary!"
"You think so? Place your hand upon my chest, just over the heart, and keep it there." With that, Brama changes his position, takes up a curious posture, and closes his eyes.
I obey his command and then wait patiently to see what is going to happen. For some minutes he remains as steady as a rock, and almost as motionless. Then the beating of his heart begins to diminish gradually. I am startled to feel it become slower and slower. A thrill of eerieness spreads over my nerves as I distinctly feel his heart completely stop its rhythmic functioning. The pause lasts for about seven anxious seconds.
Thereafter, Brama demonstrated that pulse can be stopped.
As if in answer to my unspoken thought, Brama says:
"It is nothing compared with what my master can achieve. Sever one of his arteries, and he is able to control the flow of blood; yes, even to stop it! I, too, have brought my blood under some measure of control, but I cannot do that."
" Can you show me that control? "
He requests me to take his wrist and grip it where I can feel the flow of blood through his artery. I do so.
Within two or three minutes I become aware that the curious rhythm which beats under my thumb is lessening. Soon it comes to a definite halt. Brama has brought his pulse to a stop!
I anxiously await the resumption of circulation in his artery. A minute passes but nothing occurs. A second minute, during which I am acutely conscious of each second, likewise ticks itself away in my watch. The third minute is equally fruitless. Not until half-way through the fourth minute do I become conscious of a faint return to activity within the artery. The tension is relieved. Before long, the pulse beats at its normal rate.