HI Brian and Joao
IT is an interesting idea that pallidotomy is the cutting of a
overactive movement feedback loop . It might explain PD freezing as
an overactive feedback .
However feedback loops are designed to increase control . So the
destruction of a feed back control would naturaly result in less
control . I do not think this is the case in pallidotomy . If you
are saying that the amplitude/volume of the feedback is being reduced
by pallidotomy . Then it is difficult to understand how pallidotomy
reduces and does not cut off the feedback .
PD = lack of dopamine implies an underactive brain . The sugestion
that pallidotomy reduces an over active feedback control system implies
an overactive brain . This problem occurs in any explanation of PD =
lack of dopamine and therefore a decrease in brain activity ,when
you take onboard that pallidotomy must by its very nature reduce
brain activity .
I have no right answers and will take on board this feedback idea in trying
puzzle out what PD is . Thank you .
> Hello Brian ,
>
> Brian Collins wrote:
>
> > On Wed 10 Feb, Joao Paulo Carvalho wrote:
> > > Barb , the point I was to trying to get across was how to explain that
> > > destroying more dopamine producer neurons (and other brain cells) with
> > > Pallidoctomy the result is then, paradoxically , the reduction of the
> > > need of the intake of levodopa .(remembering that the culprit of the
> > > symptoms is attributed to the shortage of dopamine in the brain)
> > >
> > Hello Joao Paulo, Your e-mail above tells me that you are missing one
> > important point in the story of Pallidotomy: The object of a Palidotomy
> > is not to damage brain cells (although a few may be accidentally damaged)
> > and it is certainly not to damage Dopamine-producing cells. The site
> > where all the Dopamine for the control of the major parts of our body
> > is the Substantia Nigra, and the Pallidotomy aims to partially sever
> > a bundle of nerve fibres in the Globus Pallidus (hence the name). My
> > way of explaining it is that the operation 'turns down the volume' of
> > the feedback nervous systen (All control systems require a feedback loop
> > to tell the main motor system how it is progressing). In a PWP's brain,
> > this return signal is swamping the output signal. I hope this helps,
> > Brian Collins <[log in to unmask]>
>
> Interesting to know that Brian because until then I had the impression that
> the
> area ( or path ) would be in which there were a blockage ,else a over firing
> ,
> in the flux of the neurotransmitters and so causing the symptoms .Could this
> be possible to occur ??
>
> Also to the best of my knowledge referring your statement " (although a few
> may be accidentally damaged) " I think Pallidoctomy aims to destroy some
> specific and particular brain cells in the Pallidus zone.
>
> Warm regards ,
>
> --
> +----| Joao Paulo de Carvalho |------ +
peace
Alastair ( [log in to unmask] )
