On Sun 15 Feb, Dennis Greene wrote:
> Brian Collins wrote:
>
> >As you
> > probably know, you are down to the last 20% of your
> Dopamine-producing cells
> > when the symptoms show,
>
I am sure that the numbers that are quoted in the '20% of remaining cells'
discussions are based on post-mortem examination. However, I doubt whether
the actual percentage of cells that are left when PD symptoms show up have
been counted with any great accuracy. I have actually heard the number quoted
as 10% instead of 20% one some occasions. Setting aside the question of
precision and accuracy for a moment, we can get down to the essential facts
that we need to know. All the arguments that I use would work quite OK if I
simply stated: 1. When we are born, a normal person has 'several times' the
number of dopamine-producing cells than he/she needs to function correctly.
2. For every person, there is a critical number of cells, which may be defined
as the number below which PD symptoms will become evident. I don't know how
consistent that number of cells is for different people , but I don't think
it matters much , one way or the other. All we need to know is that the
'critical number' exists, and from that point onward remains as the definition
of how much dopamine is required to prevent PD symptoms in that particular
person.
Did you note how I slipped sneakily from talking about number of dopamine
-producing cells to talking about 'how much dopamine is required ' etc,,,
This again is a legitimate move: All I have done is apply a calibration
to my variable - a calibration whose value I don't know, but this doesn't
matter either. Such arbitrary changes are all part of the wonderful world of
deductive logic. Whether your cherished conclusion holds water or not when
scrutinised by your peers, is the critical test of your logic.
Only those specialists who have actually dissected a brain, applied dyes
to the samples and observed the result, can talk meaningfully in terms of
absolute values. There is no way that I, as an Engineer can communicate on
that level, but I can try to express my ideas in the form of these models,
and thereby create something which those less technically inclined can
understand and apply to get a better grasp of the subject under review.
Regards,
--
Brian Collins <[log in to unmask]>
