[Bjorn Simonsen (2005.10.04,11:55 EST)]
I
visited the state hospital last week for a NCV (Nerve Condition Velocity Test)
and a EMG (Electromyography). It is nothing serious, just a routine to get a
diagnosis in my knees.
I
had a converse with the neurologist and I showed him the CSG-web. The starting point for doing that was our
discussion about the Tendon Reflex. I mentioned the feedback signal and the
Tendon Receptor. I think I said “a sensory cell” in the Tendon and he arrested
me and said that there are no neurons in the Tendon. I know the Golgi Tendon
Receptors are clustered near the Tendon, but I thought it also were on the
Tendon.
BCP
tells us page 83 that the Golgi cells are clustered on and near the Tendon. Is
this still correct? Then I will arrest the neurologist.
This
was a long story before my next question. I had to re-read BCP chapter 7 (the
new release is in the post to Norway) and I really understood the Tendon Reflex
better. Look also to http://www.kcl.ac.uk/teares/gktvc/vc/lt/mspindle/spinmain.htm
and then Dynamic Bag
1 Fibre Response.
Don’t
look at http://www.dushkin.com/connectext/psy/ch02/spinal.mhtml
because this is wrong.
Back
to my question. At the pages 84 and 85 we read: 1.) e = r – p 2.) p = ke
3.) p = kr/(1+k).
Page
87: ………. The act so as to maintain the perceptual signal at nearly the same
magnitude as the reference signal. (this is OK, -my words) This result remains
essentially true despite a variety of changes which without the feedback to the
subtractor neuron, would drastically alter the sensory signal.
I
think I understand the last sentence, but I need a verification/denial. I read
it as: If the sensory signal did not go to the subtractor neuron, and we did
not have a feedback, the sensory signal would not change.
My
last question is from the same page.
We
have a feedback system. The constant of proportionality is 10 and p = 10*r/11.
If
we imagine that the cell is more sensitive and the constant of proportionality
is 20, p = 20*r/21.
20r/21
is about 5% greater than 10r/11.
But
if k = 20, then p = ke = 20e, and the muscle tension would get a doubled
magnitude.
I
understand that we use a greater constant of proportionality (20) because this
muscle is more sensitive.
Let
us think upon the two muscles at the same time. (10 and 20)- Let us go backward
around the loop. We go from the sensory nerve over the muscle to the error, e.
If k= 10, then (1.) e = r- p) —
1.) e = r- 10e. 11e = r e = r/11
If k= 20, then 1.) e = r – 20e — 21e = r ----- e = r/21
If
k changes from 10 to 20, there is a drop in the error signal from r/11 to r/21.
Then
the muscle contraction should not be so intense, but the muscle is more
sensitive (20). Therefore it will contract more than if k = 10.
And
now, my uncertainty. The two last sentences in the section.
Am
I correct if I say. Think upon k = 10. The reference signal and the perceptual
signal are almost in balance. That is e is near zero. If k becomes 20, p = 20* e. This is a rise in the perceptual signal. But if e was near zero
and p becomes greater, than e becomes negative. And that doesn’t’ work.
I
know I am wrong, but I don’t know where.
bjorn