X-Message-Number: 8005
From:  (Thomas Donaldson)
Subject: Re: CryoNet #7985 - #7992
Date: Sat, 5 Apr 1997 00:29:22 -0800 (PST)

Hi guys!

In response to Mike Perry's comment about the thalamus, I will point out that
a few issues ago PERIASTRON described several articles discussing exactly
that issue by neuroscientists of various kinds, including Kristof Koch, who has
worked intensively with Francis Crick.

The papers were all in the journal CONSCIOUSNESS AND COGNITION, in 1995. One
writer, a Joseph Bogen, defended a theory about the importance of our 
thalamus to consciousness. (This idea apparently has a long history, but was
eclipsed for a while by the popularity of a very rigid version of behaviorism).
The exact role of our thalamus, or some specific region in our thalamus 
(several parts of our thalamus have very clearly understood roles already) 
in consciousness was part of the discussion. 

My personal belief/suggestion/hypothesis is that these regions of our 
thalamus play an essential role in our consciousness, not as a "seat" of
consciousness but as part of the neural circuits which produce it. And yes,
these ideas strongly suggest that many animals are conscious, and raise 
issues about whether or not someone might have two consciousnesses if their 
brain has been split a la Gazzaniga. At that time, one thing I have wanted
to see, which still has not been done, is a test using PET scans on normal
people to find what areas of their brains are active when they are conscious
versus unconscious (sleeping but not dreaming). Naturally this would be done
in the same way many other such studies have been done: look at many different
people engaged on different activities in all of which they are conscious,
and then take the intersection of all the regions activated. (It's not
quite so simple as this, but basically that's the method).

This will tell us a lot about the brain areas involved in consciousness.
It may also be prolonged and expensive --- after all, PET scans aren't
cheap, and we would really want a large variety of activities of different
kinds. PET scans and MRI scans were used in just that way in some of the
work I describe in the latest PERIASTRON --- but no, they weren't looking
for consciousness, but for attention. 

In animals we used to stick electrodes into their brains. Clearly there's
a limit to this, and certainly we can't do it with humans. But PET scans
and MRI scans let us work out just what brain regions are active when
human beings are doing all sorts of things --- the study has barely begun.
And since too many electrodes will make brains work badly, it's even used
now on animals.

			Long long life,

				Thomas Donaldson

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