When we fall asleep or go into a coma, the greater part of our consciousness recedes from the surface and plunges into the depths of the subliminal being. But there still persists a life-force within the body which can remember and respond when presented with an external stimulus. Writing in the early part of the twentieth century, Sri Aurobindo had outlined this condition of consciousness in his work The Life Divine. Medical science is now offering experimental validation of his observation as adduced from a couple of experiments discussed in this article.
(This blog post is superseded by a new article “Mental awareness in comatose patients and sleeping newborn infants“)
Newborn babies respond to stimulus
The first experiment conducted on babies as described on the Discover Magazine blog
Researchers recruited one- and two-day-old infants for the study, published in the Proceedings of the National Academy of Sciences. With each sleeping baby, the researchers played a musical tone and followed that by a puff of air to the eyes, a mild annoyance that caused the infant to automatically scrunch up its eyes. As this sequence of events was repeated, the sleeping babies learned to associate the air puff with the tone, and soon began to to tighten their eyelids as soon as they heard the musical note, even if the air puff didn’t follow. Electrodes stuck to their scalps also showed activity in the prefrontal cortex, which is involved in memory.
“It’s surprising how quickly they learned — the study took 30 minutes, but I think they actually learned this in half that time,” said researcher William Fifer, a developmental neuroscientist at Columbia University in New York. “We knew that a baby’s job is to be an information gatherer, a data sponge, but I don’t think we realized this also happens when they’re sound asleep.”…Neuroscientist Tristan Bekinschtein, who conducted the study on coma patients, says the work on infants suggests that there may be more gradations of consciousness than we understand.
(For more on this, see Discover Magazine blog)
Coma patients respond to stimulus
The second experiment conducted on coma patients also from the Discover Magazine blog.
Some coma patients who appear to be completely unresponsive to the outside world are still capable of the most basic kind of learning, according to a small new study. Researchers found that both vegetative and “minimally conscious” patients were capable of a Pavlovian response, learning to associate a noise with a slightly unpleasant stimulus.
The researchers built on the work of 19th-century Russian psychologist Ivan Pavlov, who famously conditioned his dogs to salivate at the ring of a bell by associating the sound with the presentation of food. In this case, they sounded a tone, which was followed about 500 milliseconds later with a light puff of air to the eye [Scientific American]. At first the patients only responded after the puff of air by blinking or twitching or flinching. But after repeated trials, 15 of the 22 patients began to blink or flinch immediately after the tone sounded, before the puff of air. Electrodes by their eyes picked up the subtle muscle movements.
A control experiment doing the same tests on people under general anaesthesia did not produce the same responses, suggesting that the learning does not happen when truly unconscious [BBC News]. The study also suggests that even patients in persistent vegetative states may have some very rudimentary level of consciousness that isn’t detected in other tests.
(For more on this, see Discover Magazine blog.)
In the following passage from The Life Divine, Sri Aurobindo expatiates on the mental memory, capable of responding to external stimulus, which persists during trance and comatose conditions of consciousness.
…Even when a form appears to us to be dead, this (life-)force still exists in it in potentiality although its familiar operations of vitality are suspended and about to be permanently ended. Within certain limits that which is dead can be revived; the habitual operations, the response, the circulation of active energy can be restored; and this proves that what we call life was still there in the body, latent, that is to say, not active in its usual habits, its habits of ordinary physical functioning, its habits of nervous play and response, its habits in the animal of conscious mental response. It is difficult to suppose that there is a distinct entity called life which has gone entirely out of the body and gets into it again when it feels—how, since there is nothing to connect it with the body?—that somebody is stimulating the form. In certain cases, such as catalepsy, we see that the outward physical signs and operations of life are suspended,but the mentality is there self-possessed and conscious although unable to compel the usual physical responses. Certainly, it is not the fact that the man is physically dead but mentally alive or that life has gone out of the body while mind still inhabits it, but only that the ordinary physical functioning is suspended, while the mental is still active.
So also, in certain forms of trance, both the physical functionings and the outward mental are suspended, but afterwards resume their operation, in some cases by external stimulation, but more normally by a spontaneous return to activity from within. What has really happened is that the surface mind-force has been withdrawn into subconscious mind and the surface life-force into sub-active life and either the whole man has lapsed into the subconscious existence or else he has withdrawn his outer life into the subconscious while his inner being has been lifted into the superconscient. But the main point for us at present is that the Force, whatever it be, that maintains dynamic energy of life in the body, has indeed suspended its outer operations, but still informs the organised substance.
Sri Aurobindo, The Life Divine – I: Life
This is a related anecdote from the journal of the Mother Mirra Alfassa, where she illustrates how a comatose patient could be mentally conscious but physically inexpressive.
…a woman who has been in a coma for sixty-five days….After fifty or fifty-five days (the whole family was around her, but her son had gone to work), all of a sudden after fifty-five days, because her son had left, she started calling for him, shouting frantically! I think they all had a scare…. And the usual stupid remarks: “She was unconscious.” I said, “Good God! But why do you say she was unconscious, you know nothing about it’… She can’t express herself, but she isn’t unconscious.” She is entirely conscious, only the means of expression are damaged, she can no longer use them.
The Mother, Mother’s Agenda: October 21, 1967