Try to say that from within those states. Try to prove a brain in deep sleep state. All those statements refer to observations (of brain or its activities) by the waking in a third person. Kindly, do not propose that they are evidences of the sleep or dream states. So, a fleshy brain is only known with waking time consciousness.
You asked me not to say what is obvious--that we know a lot about unconsciousness from introspection and from observation of the behavior of others. That constitutes evidence of dream states, loss of consciousness, and conscious awareness. Moreover, we can now record brain activity during these states. There is less brain activity in certain areas of the brain when people are not conscious. The brains of Alzheimer's victims have distinctly different physical profiles from those who do not suffer from the disease. Hence, we can correlate mental activity with physical activity in a brain. The evidence is quite convincing that the destruction of the brain most likely leads to permanent loss of consciousness.
OTOH, in deep sleep man exists and a deep repair and rest takes place. How so? Deep sleep is full consciousness of the nature of joy. One does not know anything in it because the mind-senses have not created any boundaries that may reflect consciousness back. Mind-senses rest on this full pre-concsiousness called prajna (pre-awareness). Knowing this prajna fully allows one to be restful like in deep sleep yet fully alive.
Yogins have developed wonderful mental and physical exercises. I myself was trained in some Hatha Yoga and pranayama techniques, although I no longer practice many of them--mostly just conscious relaxation.
However, none of that has anything at all to do with whether the mind can exist independently of a brain. Yes, the brain does seem to modify itself during sleep, and that is likely a kind of natural self-maintenance. Sleep is usually a physical requirement in organisms with brains. We get tired, and we fall asleep.
Where does consciousness go when we are under general anesthesia? Every time I have had it, I have woken up with the feeling that no time had passed and with no memory of the operation. I lost consciousness because of drugs that physically changed the state of my brain. Loss of consciousness cannot be resisted under those conditions. Therefore, the brain must control consciousness, not vice versa.
Rather brain is never known in absence of consciousness.
I don't understand this statement. In what sense is the brain known when we have consciousness and not known when we are without it? Other people have seen me unconscious, and I believe that my brain was still in my head at the time.
Further, It shows that consciousness has control over the so-called chemical activities and not the other way around.
I'm sorry, but it is the other way around. When a person's brain is destroyed, that person dies. When it is damaged, that person's mental capacity is damaged. It is true that thought affects the brain and the body, but those thoughts are always generated by physical brain activity.
Scientific data is always correct but often scientists are like little children holding on to their fancies. What does placebo mean? If I can consistently ubse a so-called placebo effect to calm my chemical reactions and frayed nerves then what does it prove? Consciousness controls the chemical reactions or chemicals control the consciousness?
A placebo is a sham cure that works because belief in its curative powers strengthens the immune system. It proves that belief has an effect on the body's natural defense mechanisms, but why should this be a surprise? After all, we can move our body parts through sheer mental effort. That's the whole point of a brain--to control a body. Animals evolved brains, because brains keep their bodies alive by moving them away from danger and towards safety, sustenance, and opportunities for reproduction. We can build robots that mimic that behavior, and we may some day build machines that can think like we do.
(Actually, most people are indeed controlled by their nature, without their conscious knowledge because they do not know the reality. They have placed faith on their body being 'me'. But meditators and yogis reverse the primeval conditioning that arises from the fatal idea that body is 'me'.)
I understand that you believe this, but it is not what I believe. I think they do it all with physical brains that produce their mental states.