<p>As explained in <a href="http://compneuro.uwaterloo.ca/publications/eliasmith2003a.html" rel="nofollow">the NEF book</a>, all non-linear dynamical systems can be represented in the NEF.</p>

<p>The SPA is simply applying semantic meaning and manipulations to the vectors represented by the NEF. The two most prominent examples of this are the motor system and the inference system in Spaun, which are shown in the aforementioned "rapid variable creation" task.</p>

<p>The vision system represents symbols (numbers) which get sent to the inference system. The inference system figures out the answer and sends it to the motor system. The motor system converts the symbol to a path and follows it.</p>

<p>Adding dynamics in a similar system with dynamics being visually identified, manipulated and then output, instead of static paths. One could imagine a system where the dynamics of the movement of an object are identified, manipulated neurally and then imitated. For example, having the running of a cheetah represented a series of limb movements, mapping them onto the human body and then having a human imitate that gait.</p>

<p>Of course this hasn't been implemented yet (and would look quite silly), but it shouldn't be super difficult. The main problem would be a good "demo" or psychological data to match, but I think this is still a good example. </p>

CC BY-SA 3.0
2016-05-24T18:22:34.917Z
2016-05-24T18:22:34.917Z
Seanny123
<p>Most uses of SPA I've seen seem to be representing static systems, such as recognizing digits, categorizing images, <a href="https://www.youtube.com/watch?v=Q_LRvnwnYp8" rel="nofollow">rapid variable creation</a> (also called "completing a pattern") and planning a path for writing those digits back out. Can it be used to represent dynamics as well, such as the general movement from a series of images?</p>

CC BY-SA 3.0
2015-03-04T16:33:12.870Z
SPA = semantic pointer architecture?
Josh
CC BY-SA 3.0
2015-03-04T22:17:00.223Z
@Josh yeah, it was one of the tags, so I thought I didn't need to define it in the question
Seanny123
CC BY-SA 3.0
2015-03-04T22:20:14.550Z
I think it should be spelled out in the title, so that it is easier to parse the question right away.
Josh
CC BY-SA 3.0
2015-03-05T21:22:05.620Z
Is this related to Chris Eliasmith's recent book?
mrt
CC BY-SA 3.0
2015-03-06T12:32:17.117Z
@mrt yes, I'm also taking his class, so I write down questions that come up and try to answer them to help my understanding
Seanny123
CC BY-SA 3.0
2015-03-06T18:26:48.750Z
Oh, cool.  I don't know too much about Spaun, but there was a [recent chapter](http://cogsci.uwaterloo.ca/Articles/thagard-schroeder.emotions-pointers.2013.pdf) applying SPA to emotions (as higher-order emergent "dynamic" phenomena).  Not sure if this is relevant to your question, but it may be of interest.
mrt
<theoretical-neuroscience><cognitive-modeling><spa>
How can Semantic Pointer Architecture be used to capture dynamical systems?
Seanny123
# How can Semantic Pointer Architecture be used to capture dynamical systems?

(Asked by: username_0 on 2015-03-04)

Most uses of SPA I've seen seem to be representing static systems, such as recognizing digits, categorizing images, [rapid variable creation](https://www.youtube.com/watch?v=Q_LRvnwnYp8) (also called "completing a pattern") and planning a path for writing those digits back out. Can it be used to represent dynamics as well, such as the general movement from a series of images?

**Tags:** theoretical-neuroscience, cognitive-modeling, spa

> **Comments:**
> **username_1**: SPA = semantic pointer architecture?  
> **username_0**: @username_1 yeah, it was one of the tags, so I thought I didn't need to define it in the question  
> **username_1**: I think it should be spelled out in the title, so that it is easier to parse the question right away.  
> **username_2**: Is this related to Chris Eliasmith's recent book?  
> **username_0**: @username_2 yes, I'm also taking his class, so I write down questions that come up and try to answer them to help my understanding  
> **username_2**: Oh, cool.  I don't know too much about Spaun, but there was a [recent chapter](http://cogsci.uwaterloo.ca/Articles/thagard-schroeder.emotions-pointers.2013.pdf) applying SPA to emotions (as higher-order emergent "dynamic" phenomena).  Not sure if this is relevant to your question, but it may be of interest.  

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## 1 answers

### Answer by username_0 on 2016-05-24. Score: 1

As explained in [the NEF book](http://compneuro.uwaterloo.ca/publications/eliasmith2003a.html), all non-linear dynamical systems can be represented in the NEF.

The SPA is simply applying semantic meaning and manipulations to the vectors represented by the NEF. The two most prominent examples of this are the motor system and the inference system in Spaun, which are shown in the aforementioned "rapid variable creation" task.

The vision system represents symbols (numbers) which get sent to the inference system. The inference system figures out the answer and sends it to the motor system. The motor system converts the symbol to a path and follows it.

Adding dynamics in a similar system with dynamics being visually identified, manipulated and then output, instead of static paths. One could imagine a system where the dynamics of the movement of an object are identified, manipulated neurally and then imitated. For example, having the running of a cheetah represented a series of limb movements, mapping them onto the human body and then having a human imitate that gait.

Of course this hasn't been implemented yet (and would look quite silly), but it shouldn't be super difficult. The main problem would be a good "demo" or psychological data to match, but I think this is still a good example.


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