Many time during meditation whole body feels the flow of electricity like the thing is it bio electricity or something else why this occurs but after that generally, I felt so miracle experience....how and what is this...
We have neurotransmitters (brain chemicals) in our brain, and these are the transport system of our neuron communication i.e. receive a message from the body, send to the brain, it processes and sends an instruction back through neurons to specific muscle/tissue/organ to act accordingly- This communication occurs in millions of message per day. Plus, we have other mental processes too, like anxiety, fear, stress, etc, which leads to muscle and nerve tension too.
During meditation, your brain starts focusing and start acquiring a beta state this means all the imbalance of brain chemicals or over functioning of those neurons start minimizing, your muscles tissues receives thousands of messages in a sec, to become calm, this immense communication - the release of your muscles tension and chemical balance process and a lot more happens during meditation. That is why you feel sensation or in your language electric impulses. Some people don't find it comfortable and leave meditation because of this unexplainable experience, although if they do it persistently for 7 days, they will become habitual and will see the amazing impact on their lives.