Re: TECH/SCI: Brain Changes

From: Robert Bradbury (
Date: Tue Apr 25 2000 - 08:33:48 MDT

On Mon, 24 Apr 2000, Natasha Vita-More wrote:
> Specific statements that caught my eye:
> 1. "... senses of smell, taste, touch, sight and hearing have decreased at
> a rate of nearly one percent per year."
It is generally true that sensory perception does decline with age
among gerontologists. For example, the elderly generally have poor
nutrition. This is attributed in part to a decreased ability to
smell and taste the food. It is less appealing so people eat less.
Eyesight and hearing are well documented to decrease with age.
I'm not sure how much of the eyesight decrease is neural in nature
because you would have to separate out the decrease in the transparency
and flexibility of the lens.

> I'm not entirely sure that we have eliminated the capacity. We do know
> that people who listen to loud music (usually rock music) have a decreased
> auditory sense, but I'm not sure that this applies to everyone.

I think that the declines are fairly universal. If you want some
concrete references, send me a note off-list and I'll go through
my gerontology books when I get back to Seattle. The "Baltimore
Longitudinal Study on Aging" would be the place to start for
pysiological changes in the general population with age.

> 2. "Our brain is not adapting."
I would probably disagree with that. There is general consensus that
the brain does adapt and replace decreased sensory perception with
accumulated knowledge regarding the information that is likely to be
present. Perhaps the type of adaption they were seeking does not

> 3. "Red is no longer real red."

I'm not going to touch that statement since it will likely restart
the qualia wars... :-)

As a general comment I would say that it is clear that we are losing
neurons with age. This was at first believed, then refuted and now
with very very good techniques is believed to be true for normal
aging in individuls. I don't recall the exact figures, but the loss is
significant enough that you do have to worry about having half-a-brain
when you get into the multi-hundreds of years age-group. So one of
the problems we will need to solve to get bio-humans into the thousand
year lifespan era will be the implantation and outgrowth of neuronal
stem cells. However it would be really strange if the singularity
did not arrive for most of the people on the planet long before they
are needed.


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