The reflex arc - knee jerk - A PCT account?

Hi all,

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

PS - I remember reading that the knee jerk reaction (funnily enough) has a large degree of variability that has not yet been explained. Perhaps this is an artifact of using an open loop model.

···

Cheers,

**Sean Mulligan **

**lack.of.inspiration@gmail.com **

[From Richard Kennaway (2017.10.29 09:24 GMT)]

Sean Mulligan lack.of.inspiration@gmail.com writes:

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen
when you apply an impulse to
a control system, i.e. a disturbance faster than the control system is able to respond to. It
is generating an output that arrives after the disturbance has already passed.

There’s a discussion of reflexes and control systems in a chapter of a neurophysiology textbook available
online at http://michaeldmann.net/mann15.html . I don’t know if anyone has made a physiologically based mathematical
model of the knee jerk reflex.

– Richard Kennaway

[From Rick Marken (2017.10.29.1115)]

Richard Kennaway (2017.10.29 09:24 GMT)_-

Sean Mulligan <<mailto:lack.of.inspiration@gmail.com>lack.of.inspiration@gmail.com> writes:
SM:Â Was wondering if anyone has come up with a PCT account for the knee jerk reflex?Â

RK: I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen when you apply an impulse to a control system, i.e. a disturbance faster than the control system is able to respond to. It is generating an output that arrives after the disturbance has already passed.

RM: Here's what I had to say about it in a paper I wrote called "The Illusion of No Control" which I was never able to get published in the kind of journal that I thought it deserved to be published in so it is published only as a chapter in my book "Doing Research on Purpose" (<https://www.amazon.com/Doing-Research-Purpose-Experimental-Psychology/dp/0944337554>https://www.amazon.com/Doing-Research-Purpose-Experimental-Psychology/dp/0944337554):

Reflexes. The prototypical example of behavior that involves no control – involuntary behavior – €“ is the reflex. A familiar example is the patellar or “knee-jerkâ€? reflex that occurs when the patellar tendon (just below the kneecap) is hit with a hammer (Weiner, 2010). The knee-jerk seems to be an involuntary response to the hammer tap; it is a behavior that seems to involve no control. In fact the patellar reflex is part of a control system that is aimed at controlling the perceived angle of the knee or a variable, such as muscle length, that is related to this angle. The normal disturbance to this variable is changes in the forces on the knee that are produced while walking, running or lifting. The hammer tap is an artificial disturbance that is equivalent to a sudden force, such as landing on the foot while running, that would buckle the leg. The knee jerk results from the muscle contraction that counters this disturbance and prevents buckling.

The Illusion of No Control occurs in reflex behavior when the disturbance to the controlled variable is abrupt, as it is in the case of the patellar reflex. The abrupt tap disturbance to knee angle, which makes it seem like the knee has buckled, is removed just as the control system is causing upward muscle forces that would maintain the current angle. But the knee angle never really changed so the upward restoring forces lift the foreleg unnecessarily and what is seen is a kick in response to the tap stimulus. The fact that control is going on in the patellar reflex can be seen more clearly by holding the TCV up to this behavior. This is done by observing the effect on the presumed controlled variable, knee angle, of disturbances that vary fairly smoothly over time, as they do during running and walking. In this case control can be seen in the fact that the controlled variable remains the same each time the leg hits the ground; the knees never buckle because knee angle is protected from disturbances by the forces exerted by the leg muscles – the mmuscles that produce the apparently involuntary “knee jerkâ€? in response to the abrupt tap on the tendon.Â

RM: Simulations that demonstrate this would be nice! I don't have time to develop them myself at the moment since I will be spending my free time during the next few months trying to figure out how to demonstrate why open-loop models of the power law of curved movement are wrong. This will involve trying to get a very smart group of scientists (many of whom are ostensibly fans of PCT) to understand this; scientists whose careers and/or research funding depends on their not understanding it. Sucks to be me. But I'll get by with a little help from my friends.Â
BestÂ
Rick

···

--
Richard S. MarkenÂ
"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[Martin Taylor 2017.10.29.23.02]

Great! That's a worthwhile project, as opposed to writing a rebuttal

to Zago et al… It is, after all, just what Alex asked for when he
introduced the power-law problem in the first place.

Martin
···

[From Rick Marken (2017.10.29.1115)]…

        RM: ...I will be spending my free time during the next

few months trying to figure out how to demonstrate why
open-loop models of the power law of curved movement are
wrong.

Rick & Richard,

Thanks for the info. Found a few computational/simulation models of the knee jerk - a number using control theory - all are open loop however. It seems like an interesting problem…turning something pretty discrete into a continuous modelling paradigm. I figure I have to find a pattern of disturbances that breaks the linear model. If everyone has assumed a linear model, perhaps a how class of stimulus variations have not been used with the knee jerk. Perhaps continuous lower intensity impulses…try and create some interference by the afferent nerve feedback by messing around with the speed and intensity of the hammer hits. Will have a think. I’m pretty new to experimental design.

···

On Sun, Oct 29, 2017 at 8:37 PM, Richard Kennaway (CMP - Visitor) R.Kennaway@uea.ac.uk wrote:

[From Richard Kennaway (2017.10.29 09:24 GMT)]

Sean Mulligan lack.of.inspiration@gmail.com writes:

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen
when you apply an impulse to
a control system, i.e. a disturbance faster than the control system is able to respond to. It
is generating an output that arrives after the disturbance has already passed.

There’s a discussion of reflexes and control systems in a chapter of a neurophysiology textbook available
online at http://michaeldmann.net/mann15.html . I don’t know if anyone has made a physiologically based mathematical
model of the knee jerk reflex.

– Richard Kennaway

Cheers,

Sean

It would be great to do a version with all the physiology and anatomy. Maybe using Bruce’s new artificial limb demo when it’s ready? In the mean time, I muddled around with the live block diagram a while ago…

https://m.youtube.com/watch?v=JTdFwhGZy8A&feature=youtu.be

···

On Sun, Oct 29, 2017 at 8:37 PM, Richard Kennaway (CMP - Visitor) R.Kennaway@uea.ac.uk wrote:

[From Richard Kennaway (2017.10.29 09:24 GMT)]

Sean Mulligan lack.of.inspiration@gmail.com writes:

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen
when you apply an impulse to
a control system, i.e. a disturbance faster than the control system is able to respond to. It
is generating an output that arrives after the disturbance has already passed.

There’s a discussion of reflexes and control systems in a chapter of a neurophysiology textbook available
online at http://michaeldmann.net/mann15.html . I don’t know if anyone has made a physiologically based mathematical
model of the knee jerk reflex.

– Richard Kennaway

Cheers,

Sean

Cheers Warren. Great demo. Which program did you use to hack that up?

Will keep an eye out for Bruce’s creation. Right now there are quite a few simulations and models that I can tinker with. Probably a simple pendulum used for the leg and the simplest muscle model I can find.

···

On Mon, Oct 30, 2017 at 8:19 PM, Warren Mansell wmansell@gmail.com wrote:

It would be great to do a version with all the physiology and anatomy. Maybe using Bruce’s new artificial limb demo when it’s ready? In the mean time, I muddled around with the live block diagram a while ago…

https://m.youtube.com/watch?v=JTdFwhGZy8A&feature=youtu.be

On 30 Oct 2017, at 03:53, Sean Mulligan lack.of.inspiration@gmail.com wrote:

Rick & Richard,

Thanks for the info. Found a few computational/simulation models of the knee jerk - a number using control theory - all are open loop however. It seems like an interesting problem…turning something pretty discrete into a
continuous modelling paradigm. I figure I have to find a pattern of disturbances that breaks the linear model. If everyone has assumed a linear model, perhaps a how class of stimulus variations have not been used with the knee jerk. Perhaps continuous lower intensity impulses…try and create some interference by the afferent nerve feedback by messing around with the speed and intensity of the hammer hits. Will have a think. I’m pretty new to experimental design.

Cheers,

**Sean **

Cheers,

Sean

On Sun, Oct 29, 2017 at 8:37 PM, Richard Kennaway (CMP - Visitor) R.Kennaway@uea.ac.uk wrote:

[From Richard Kennaway (2017.10.29 09:24 GMT)]

Sean Mulligan lack.of.inspiration@gmail.com writes:

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen
when you apply an impulse to
a control system, i.e. a disturbance faster than the control system is able to respond to. It
is generating an output that arrives after the disturbance has already passed.

There’s a discussion of reflexes and control systems in a chapter of a neurophysiology textbook available
online at http://michaeldmann.net/mann15.html . I don’t know if anyone has made a physiologically based mathematical
model of the knee jerk reflex.

– Richard Kennaway

[From Bruce Abbott (2017.10.30.0910 EDT)]

···

From: Sean Mulligan [mailto:lack.of.inspiration@gmail.com]
Sent: Sunday, October 29, 2017 11:53 PM
To: csgnet@lists.illinois.edu
Subject: Re: The reflex arc - knee jerk - A PCT account?

SM: Rick & Richard,

SM: Thanks for the info. Found a few computational/simulation models of the knee jerk - a number using control theory - all are open loop however.

BA: This is a contradiction in terms, Sean. If a model is based on control theory, then it is by nature a closed loop model.

SM: It seems like an interesting problem…turning something pretty discrete into a continuous modelling paradigm. I figure I have to find a pattern of disturbances that breaks the linear model. If everyone has assumed a linear model, perhaps a how class of stimulus variations have not been used with the knee jerk. Perhaps continuous lower intensity impulses…try and create some interference by the afferent nerve feedback by messing around with the speed and intensity of the hammer hits. Will have a think. I’m pretty new to experimental design.

BA: Continuous models of the lowest-level system – the one controlling muscle length and tensionn – have been around for a very long time. Merton (1953) modelled this system as a servomechanism back in the 1950s, and Houk presented a detailed control-system model as his Master’s Thesis in 1963. Powers’ model, presented in B:CP (1973) was borrowed from Houk, although Bill did not make that attribution until he incorporated it into his “Little Manâ€? demo and published a description of it in Powers (1999). And there are others: Motor control is currently an active field of research in physiology.

BA: By the way, applying an impulse or step disturbance to a control system is a standard analytical tool for analyzing control-system performance. The classic hammer tap to the patellar tendon provides just such a disturbance.

You can download a simulation of the Level 1 controllers used in Bill Powers’ Little Man demo from my Google website at https://sites.google.com/site/perceptualcontroldemos/home/other-demos . The relevant file is ArmDynam.zip. You will need a PC to run it: download the file, unzip it, and double-click on ArmDynam.exe. (In Windows 10 you may have to grant Windows permission to “run anyway.â€?) Depicted in the simulation are side and top views of an “armâ€? with a 2 df shoulder joint (horizontal and vertical rotations) and an elbow joint (horizontal rotation). You can change the reference values for each by dragging the three sliders, and can change the parameters of each control system.

A much more physiologically accurate model is presented on the AnimatLab website at:

http://animatlab.com/Help/Documentation/Biomechanical-Editor/Biomechanical-Body-Parts/Linear-Hill-Muscle .

Bruce A.

On Sun, Oct 29, 2017 at 8:37 PM, Richard Kennaway (CMP - Visitor) R.Kennaway@uea.ac.uk wrote:

[From Richard Kennaway (2017.10.29 09:24 GMT)]

Sean Mulligan lack.of.inspiration@gmail.com writes:

Was wondering if anyone has come up with a PCT account for the knee jerk reflex?

Dewey (1896) argued that the stimulus/response model used in psychology was based on the uncritical adoption of the reflex arc concept - which is an open loop model. The knee jerk reaction is the most basic reflex arc and is the most used example in psychology.

If all regulation in the nervous system is undertaken by closed loop control systems (as PCT postulates), then the knee jerk reaction “process” should also be a control system.

If a closed loop account of the knee jerk reaction was supported (and it being the simplest reflex arc) - then wouldn’t this be a strong case for PCT across the board? It basically undermines the foundation that the “General Linear Model” is founded on.

I recall Bill pointing out a long time ago that the knee jerk reflex is the sort of thing that can happen when you apply an impulse to a control system, i.e. a disturbance faster than the control system is able to respond to. It is generating an output that arrives after the disturbance has already passed.

There’s a discussion of reflexes and control systems in a chapter of a neurophysiology textbook available online at http://michaeldmann.net/mann15.html. I don’t know if anyone has made a physiologically based mathematical model of the knee jerk reflex.

– Richard Kennaway