Fabulous. This larva brain (and body) is a lot more realistic than Rick’s recent demos, plus it is closed loop too. I wonder if its trails obey power law? Bill never liked central patten generators and thus study seems to be good evidence they are not needed? I will email the authors about PCT.
Warren
···
On 27 Jul 2016, at 17:25, Alex Gomez-Marin agomezmarin@gmail.com wrote:
[Integrative neuromechanics of crawling in D. melanogaster larvae | eLife](https://urldefense.proofpoint.com/v2/url?u=https-3A__elifesciences.org_content_5_e11031&d=CwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=-dJBNItYEMOLt6aj_KjGi2LMO_Q8QB-ZzxIZIF8DGyQ&m=OfxLUAmGb7ee8Xr0uhE8hqE0eBHbg-SYQ3iHrhAIHkE&s=7qspogTIWI3IYgdWSkigehTu2zG4qsW
9P0iv2y0KdPU&e=)
[From Rick Marken (2016.07.27.1210)]
···
On Wed, Jul 27, 2016 at 10:31 AM, Warren Mansell wmansell@gmail.com wrote:
WM: Fabulous. This larva brain (and body) is a lot more realistic than Rick’s recent demos, plus it is closed loop too.
RM: I don’t think you understand what my demos are demonstrating. My demos are not meant to be realistic models of how movements are produced. They are demonstrations of the fact that you can’t tell how movements are produced by analyzing characteristics of the movements themselves. The power law is a characteristic of the movement itself.
WM: I wonder if its trails obey power law?
RM: My demo shows that it unquestionably will obey the power law. Anything that produces curved movements over time – a realistic model, a non-realistic model, a planet, an ant, a lawn mower,etc – will obey the power law.
WM: Bill never liked central patten generators and thus study seems to be good evidence they are not needed? I will email the authors about PCT.
RM: Models that include pattern generators are designed to explain patterned behavior, such as repetitive circular hand movements. Bill objected to models that included central pattern generators for *output *simply because such models could not produce the intended pattern of behavior in a disturbance prone environment. Bill certainly had no objection to models that included central pattern generators for input because such models can produce the intended pattern of behavior in a disturbance prone environment; such models are PCT model.
RM: A central pattern generator for input is a reference signal that varies over time in a patterned manner. In PCT, these patterned temporal variations in a reference signal would be the output of higher level control systems that are controlling for the result of that temporal pattern. For example, a higher order system that wanted to perceive your hand moving in a circle would have a reference for perceiving a circle being produced by your hand movement; the output of this higher level system would be time varying references for the X and Y position of the hand that results in the perception of a temporal sequence of circular movements of hand position.
RM: The model I posted is the lower level systems that have their time varying X, Y references for input sent from higher level systems; the specific temporal pattern of X, Y references depends on the pattern of hand movement that the higher level system want to produce. Here it is again:
RM: In this model, r.x and r.y are “pattern generators” for generating a temporal pattern of input, not output.
RM: But, again, this model will produce movements that obey a power law no better than any other model; no better than the movements of the planets or a lawn mower. All curved movements follow a power law; you can’t determine how curved movements were produced – you can’t determine the appropriate model of the movement producer – by just looking at the movements themselves (which is what you are doing when you are looking at V, R, A or C - all just different measures of the same movement).
Best
Rick
Warren
On 27 Jul 2016, at 17:25, Alex Gomez-Marin agomezmarin@gmail.com wrote:
–
Richard S. Marken
“The childhood of the human race is far from over. We
have a long way to go before most people will understand that what they do for
others is just as important to their well-being as what they do for
themselves.” – William T. Powers
Warren, their larval model is only for forward crawling. No backwards, nor bending or turning. This is for the future.
···
On Wed, Jul 27, 2016 at 7:31 PM, Warren Mansell wmansell@gmail.com wrote:
Fabulous. This larva brain (and body) is a lot more realistic than Rick’s recent demos, plus it is closed loop too. I wonder if its trails obey power law? Bill never liked central patten generators and thus study seems to be good evidence they are not needed? I will email the authors about PCT.
Warren
On 27 Jul 2016, at 17:25, Alex Gomez-Marin agomezmarin@gmail.com wrote:
Hi Rick, I can see your point. What I am saying is taking what you say further. I am saying that not only can we it explai the power law through the outputs of the organism, but we also cannot explain the perceptual control systems of the organism by assuming the the patterned movement observed is specified input; just like you can’t assume that the squiggle in a rubber band task is specified input. It’s not. It is the side effect of controlling something much simpler - a knot over a dot. Surely a PCT explanation has to consider this and go beyond what you have shown so far. I do not think that a larva has a CPG for input to ‘draw’ the shape it ends up moving. Neither does a mindless human squiggler, nor many other animals I am sure…
So I am not saying what you say is not true, just that it is not answering the important question…
···
BT
On Wed, Jul 27, 2016 at 10:31 AM, Warren Mansell wmansell@gmail.com wrote:
WM: Fabulous. This larva brain (and body) is a lot more realistic than Rick’s recent demos, plus it is closed loop too.
RM: I don’t think you understand what my demos are demonstrating. My demos are not meant to be realistic models of how movements are produced. They are demonstrations of the fact that you can’t tell how movements are produced by analyzing characteristics of the movements themselves. The power law is a characteristic of the movement itself.
WM: I wonder if its trails obey power law?
RM: My demo shows that it unquestionably will obey the power law. Anything that produces curved movements over time – a realistic model, a non-realistic model, a planet, an ant, a lawn mower,etc – will obey the power law.
WM: Bill never liked central patten generators and thus study seems to be good evidence t
hey are not needed? I will email the authors about PCT.
RM: Models that include pattern generators are designed to explain patterned behavior, such as repetitive circular hand movements. Bill objected to models that included central pattern generators for *output *simply because such models could not produce the intended pattern of behavior in a disturbance prone environment. Bill certainly had no objection to models that included central pattern generators for input because such models can produce the intended pattern of behavior in a disturbance prone environment; such models are PCT model.
RM: A central pattern generator for input is a reference signal that varies over time in a patterned manner. In PCT, these patterned temporal variations in a reference signal would be the output of higher level control systems that are controlling for the result of that temporal pa
ttern. For example, a higher order system that wanted to perceive your hand moving in a circle would have a reference for perceiving a circle being produced by your hand movement; the output of this higher level system would be time varying references for the X and Y position of the hand that results in the perception of a temporal sequence of circular movements of hand position.
RM: The model I posted is the lower level systems that have their time varying X, Y references for input sent from higher level systems; the specific temporal pattern of X, Y references depends on the pattern of hand movement that the higher level system want to produce. Here it is again:
<image.png>
RM: In this model, r.x and r.y are “pattern generators” for generating a temporal pattern of input, not output.
RM: But, again, this model will produce movements that obey a power law no better than any other model; no better than the movements of the planets or a lawn mower. All curved movements follow a power law; you can’t determine how curved movements were produced – you can’t determine the appropriate model of the movement producer – by just looking at the movements themselves (which is what you are doing when you are looking at V, R, A or C - all just different measures of the same movement).
Best
Rick
Warren
On 27 Jul 2016, at 17:25, Alex Gomez-Marin agomezmarin@gmail.com wrote:
–
Richard S. Marken
“The childhood of the human race is far from over. We
have a long way to go before most people will understand that what they do for
others is just as important to their well-being as what they do for
themselves.” – William T. Powers