13 March 2010

The man who dies every day

A month ago, I wrote about myself and other myths–some interesting scientific results from research into the nature of consciousness. I missed a couple, however.

For many years, scientists have studied the nature of sleep, and of dreams. These studies have started to overlap with those looking at the nature of consciousness. One experiment involves stimulating the brain using transcranial magnetic stimulation or TMS, and watching the outcome on an FMRI scanner as the patient is gradually anesthetized or allowed to fall asleep.

In the conscious, self-aware mind, TMS results in patterns of excitation that range over large areas of the brain. This kind of non-localized excitation is now being used to prove that coma victims are not brain-dead; they are asked to visualize playing a game of tennis, which produces an easily measurable and distinct excitation pattern in FMRI scans.

So similarly, TMS excitation of a conscious mind produces a clearly distributed pattern of neural firing. In a non-conscious mind, the excitation is highly localized and remains wherever the stimulation occurs. In a dreaming mind, the excitation stimulates adjacent areas, but doesn’t range as far as in the conscious mind. This new model of consciousness is known as the global workspace theory.

So in effect, the difference between being alive and being in a coma is like the difference between a lab full of disconnected computers, and a lab full of computers connected via a network. Dreaming is like a degraded network where the signals are rerouted to nearby systems instead of their proper destination.

What struck me as shocking is this: When you’re in deep sleep, not dreaming, the network is down–exactly like when you’re in a coma, or have just died. The difference between being awake and being in non-dreaming sleep is a difference of kind, not of degree. Awake versus dreaming, on the other hand, that’s a mere difference of degree. And non-dreaming sleep versus coma–well, that’s a difference so subtle that we don’t really understand it, and it seems to have nothing to do with thought patterns.

In other words: My conscious self-awareness, the mythical “myself”, literally ceases to exist every night, just as much as it would if I actually died. There is no “me” until I start dreaming, at which point self-awareness re-emerges partially as the network comes back online. The fact that I’m a lucid dreamer is probably just my network activating more than average.

As the ancient Greeks put it, “sleep and death are brothers”. The Bible uses sleep as a metaphor for death. Now science is starting to discover that our ancient intuitive guesses about the nature of sleep and of death are pretty close to the truth.

I had always assumed that what made me me was some sort of continuity of mental process; that when I went to sleep, the activities that are me continued–just at a lower level, beneath my conscious awareness. It now looks as if this is completely wrong. But if there’s no continuity of thought process between me and the consciousness that will be animating this body tomorrow morning, then in what sense is that person actually me? He’ll have my body, and my memories, but surely that isn’t enough?

I’m only beginning to adjust my worldview to this new knowledge. The odd thing is, rather than keeping me awake at night, it’s almost comforting. If I’ve died over 10,000 times already, the thought of dying one last time seems like much less of a big deal.

© mathew 2017