http://www.sciencecentric.com/news/1...ep-closer.html

Wow! Thanks for posting this. This seems watershed to me as no one could explain the paradoxica kinesia or why only our normal everyday movements were affected but not things like riding a bike. I think we had a thread on this a while back. I was beginning to think it was partly a memory issue, but this explains it as all physiological. The next logical question they ask is one we've asked many times here. Why are those particular dopaminergic neurons more vulnerable than others? This finding could provide clues that really get us closer to the actual causes involved. Maybe they are somehow more closely connected to the olfactory and vagus nerves that show in Braak's staging as an early manifestation of the disease.

This is one to watch.

Laura

Bump.

If you wonder where freezing and slow movement come from and why it is only our habitual, automatic movements that are impacted, read the article Soccertese posted.

It seems to make a lot of sense to me and hopefully this will lead to improved treatments in the future or targeted neuroprotection.

Laura,
“Numerous experiments show that the loss of dopamine from the basal ganglia increases inhibitory output from the habitual control circuits”
I happen to be a control engineer and the article sighted makes some sense to me.
Any man made dynamic system (for example the control system driving a rocket) must include a feed forward signal defining the immediate goal for movement (intention) AND a feed back signal quantifying the actual movement achieved. In engineering terms the feed back signal is used to attenuate and correct the feed forward signal (i.e. inhibitory and it is typically called a negative feed back signal). Of course this happens in a continuous manner in infinitesimal small steps.
The science of man made control systems essentially aims at smooth movement by manipulating the feed back signal.
For example, too much negative feed back signal will make movement sluggish. Too little (negative feedback) may result in uncontrolled or oscillatory movement.
This is a simplified picture and hope it helps.
Imad

Imad, I remember reading an article in which the cause of tremor was described exactly in the same terms as as your engineering model, interestingly rigidity was also postulated in the same way - as a fine extreme of oscillation, and linked to the sensation of 'internal tremor' that many pwp with no apparent tremor feel...... for those of us who had no way to describe this prior to dx it was often put down to panic attacks, which I KNEW was not the case! It is fascinating that there is a mechanical/physical model there.....
neurotransmitters again, I think.....