Re: BOOKS: Pournelle's *A Step Farther Out*

Anders Sandberg (
17 Feb 1999 11:07:53 +0100 writes:

> I wonder what has become of the " holographic theory of the brain "- whether
> it has been refined in the meantime or simply discarded.

As far as I know, it has mutated (except for some new ageish holdovers that fervently believe in literal holograms) into the distributed model of memory storage - memories are stored as distributed patterns of synaptic strengths across the brain, just like in artificial neural networks.

> I like the idea that
> information storage in the brain could be dynamic (p82), which would imply
> that even if we can duplicate or restore brain structure, as the cryonicists
> hope nanotechnology will enable us to do, the information will be lost because
> of the intervening interruption of the brain's activity. What happens to
> comatose brains for instance ? Could the psychiatric troubles that follow
> comas stem from such an interruption ?

Some information is doubtless stored as dynamical states of some kind, but as it becomes part of long term memory it becomes more and more stable, most likely due to structureal changes of the brain. Working memory is perhaps dynamical, intermediate memory probably very flexible synapses and chemical states, long term memory morphological change.

People who are in coma are usually in a bad physical condition, when they wake up they will have to face whatever brought them into a coma, and I wouldn't be surprised that just lying in a coma might induce changes in the brain blood circulation that are deleterious. So I don't think those psychological changes are strong support for the dynamic storage model.

There are plenty of people who have had no brain activity for a while (due to cold surgery, near-drowning in cold water or coma), and they don't lose more than the memories just before the accident/surgery (besides other complications, of course).

>I also liked the idea that the
> information is encoded in the brain, and that the decoder may be damaged,
> leading to the person's inability to read the information off his own brain.
> Such a model could explain reversible amnesia, or cases of madness like George
> III's, with intermittent phases of sanity.

Yes. It fits well with current discussions of metamemory, search strategies and the tip-of-the-tounge phenomenon. We don't know how it works yet, but it seems that there are systems important for retrieval separate from encoding.

> The most disgusting part of the book is certainly the speculations concerning
> black holes, which seem to offer elbow room for the scientists' irrationality.
> " Time running backward " is a meaningless phrase if you accept the
> Aristotelian conception of time as a measurement of change and of the present
> as "all there is"; and Hawking's idea that " anything " can come out of a
> black hole is simple nonsense.

I think someone misunderstood Hawking here. I think the original idea was the problem of naked singularities, where I think Hawking (and others) have pointed out that they make physics indeterminate - if you have a naked singularity, the time evolution of physics is no longer defined. Pink elephants jumping out from the singularity cannot be ruled out. Which is why a lot of people want cosmic censorship.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y