It's not the tissue that's dead, although after time, would deteriorate, but the nervouse systems currents of electical synapsis. These thoughts (Jeff pondered), I believe to relevent to cryonics, in the sense that there may be some question as to how much of a memory can be rejuvinated. If I was climbing up in years, without the advances of technology on my side, and had to consider cryonics, I would. But it would be unfortunate if I didn't come back with all memory in tact.
Gina "Nanogirl" Miller
Nanotechnology Industries
http://www.nanoindustries.com
echoz@hotmail.com
>From: Jeff Davis
>
>Friends,
> I'm cross-posting this to the cryonet and extropians list.
>
> I've been thinking lately about brain damage. When exactly is
identity
>destroyed? I mean really obliterated?
> Specifically, I'm wondering about the difference between loss of
>information, and loss of ACCESS TO information. This last attributed
to
>the loss of higher-order function.
> When a brain is damaged--I'm thinking here of strokes, traumatic
injury,
>brain tumors, and alzheimer's--certain structural changes take place.
>Think of the spatial distribution of the damage.
> Some of those changes presumably involve actual cell death. But how
many
>cells die, what fraction of the whole is that, how is the damage
>distributed regionally/topologically, and what happens to the dead cell
>bodies? (I assume fully necrotic cells undergo apoptosis and "digest"
>themselves, the by-products being dispersed for either local or distant
>consumption or disposal.) What of "scar tissue" and other structural
>remnants?
> Then too, what degree of brain damage is characterized by cell damage
>without cell death--membrane or cytoskeletal damage/alteration;
organelle
>damage/reduced function--such that the cell still lives, but is not
capable
>of supporting the coordinated global activity characteristic of normal
>brain function?(Does this happen, or am I describing a non-fact? I
recall
>that mitochondria sometimes suffer gradual degradation from, at least,
>inherited defect.)
> When a person is brain dead, is there actually a great lump of dead
tissue
>inside the skull (I don't think so), or does the absence of brain
>waves--the flatline on the electroencephalograph that provokes the term
>"persistant vegetative state"--only suffice to imply loss of global
>function, but not large-scale cell death, maybe not even small-scale
cell
>death, or (here's the crux)maybe not nearly as much information loss
as
>we're inclined to think?
> To what extent is the topology of damage responsible for disruptions
of
>neuronal firing patterns? Could the loss of memory or personality be
due
>not to the loss of the information, but to the inability of the organ
to
>fire that pattern, due to a disrupted firing path. Would the
accumulation
>of many small areas of damage, such as in the case of alzheimer's, so
"damp
>out" the spatially dynamic, electrochemical resonance of thought--of
memory
>and personality EXPRESSION--that the person seems to fade away? In a
>man-made electronic system, a simple broken wire can result in a
complete
>system failure even though the actual structural deficit may be only an
>infinitesimally small fraction of all the atoms of the system, and the
>information deficit zero.
> Are dementia et al victims really as far gone as we fear they are when
we
>view with dismay their varying degrees of vegetative-ness? Or is the
>information there, but just not expressible?
> Identity survival is central to cryonics. Some aspects of the
(gradual)
>process of identity deterioration provoke an interpretation of
irreversible
>loss. We look at them and say "They're gone." How valid is this? How
>subject to reevaluation?
> One final detail. I'm a strong believer in the "elegant design" of
>natural systems. "Nature" squeezes as many uses out of any system
>component as she can. (Please excuse the teleological and
anthropomorphic
>modes of expression.) Thus a local brain region with a specialized
>function is likely to have multiple roles. In larger scale global
>function--like memory or personality pattern storage and expression--it
may
>have a supporting but not a critical role. Thus limited local damage
which
>may cause striking loss of specific function may, as regards memory or
>personality, have only a mild impact. In fact, let me repeat what has
been
>suggested before: that memory and personality may be broadly
distributed
>across the cortex and cerebellum (and elswhere?), that such distributed
>expression is arguably inherently robust, and that these features
strongly
>suggest the importance of memory and personality to the individual and
the
>species (not to mention to cryonicists and extropians).
>
> --------------------
>
> In the process of writing this, I produced a typo: memeory, instead of
>memory. Hmmmmmm.
> Best, Jeff Davis
>
> "Everything's hard till you know how to do it."
> Ray Charles
>
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