In every region of the cortex there are cells in Layer 5 that project someplace else in the brain that is related to motor behavior. (At least in every region people have looked.) In the classic “motor” regions the layer 5 cells project to muscles, or spinal cord, in vision areas they project to the superior colliculus which controls eye movement, etc. This tells us that most (if not all) regions of the cortex are playing a role in motor behavior. This is one reason why I think we can attack the sensorimotor problem by initially modeling a single region.
The axons from the layer 5 motor cells split and send a branch up the cortical hierarchy. So the “motor command” coming from layer 5 is also an input to the next region. When the next region learns patterns and makes predictions part of its input is the motor commands that the lower region is sending to motor areas. One twist is the feedforward motor signal is gated in the thalamus. So it doesn’t always go to the next region. Presumably this is controlled as part of attention. Remember that layer 3 is the primary feedforward inference layer, it is the model for the CLA. My guess is that layer 5 and layer 3 are entrained by columns and therefore layer 5 is learning a sequence similar to layer 3. I believe that the layer 5 cells associatively link to subcortical motor centers. They are just like the cells in the layer 3 CLA, they represent the state of the system, but they learn how control behavior by association. I can explain this better but it takes more time than I have now. I can walk through some simple examples of how a region sits on top of a body which has sensors and innate motor behavior. The region learns to model the patterns of the body as it interacts with the world through its innate behaviors. Then the region’s layer 5 cells associatively link to control the innate behavior. Now the region is able to control behavior. If the region learns complex patterns that result in desirable outcomes it can replay those complex patterns (essentially new complex behaviors) to make the desired outcome happen again. This is a form of “reinforcement learning”. Where I am struggling is how to set goals and how the system can adjust its behavior as it plays back learned behaviors. Jeff Here is a paper on how the layer 5 neurons split. http://shermanlab.uchicago.edu/files/rwg <http://shermanlab.uchicago.edu/files/rwg&sms%20BRR%202010.pdf> &sms%20BRR%202010.pdf From: nupic [mailto:[email protected]] On Behalf Of Chetan Surpur Sent: Friday, October 25, 2013 10:36 AM To: NuPIC general mailing list. Cc: NuPIC general mailing list. Subject: Re: [nupic-dev] motor implementation Hi Jeff, Just as briefly, would you mind describing from how region 5 helps accomplish this? Unless you want to save it as a surprise for your talk :) Thanks, Chetan On Fri, Oct 25, 2013 at 10:30 AM, Jeff Hawkins <[email protected]> wrote: Aseem, I will be giving an informal talk on this topic at the next hackathon, but in brief, very brief... The CLA today has no motor component. It is like an ear listening to sounds but with no ability to interact with the world. Most sensory perception is not like that. Most of the changes on our sensors come from our own actions. Imagine standing in a house. If your eyes couldn't move and your body couldn't move you would not be able to learn what the house is like. You couldn't learn the patterns in the world. Only be moving do you discover the structure of the house. Movement leads to sensory changes. The brain learns sensorimotor patterns. "when I see this and turn left I will see that". The same is true for touch. Even hearing is largely controlled by our own motions. The only thing I am hearing right now is the sounds of the keys on my keyboard. My cortex is predicting to hear those sounds. If they changed even slightly I would notice the difference. Motor behavior is how we learn most of the structure of the world. Jeff -----Original Message----- From: nupic [mailto:[email protected]] On Behalf Of Aseem Hegshetye Sent: Friday, October 25, 2013 5:37 AM To: [email protected] Subject: [nupic-dev] motor implementation Hi, Jeff Hawkins said he is working on sensorimotor design. How will implementation of motor layer 5 help in data prediction. Would it be like CLA signalling anomalies like cortex gives motor commands or are you planning on manipulating some parameters at user end based on the predictions from given inputs. thanks Aseem Hegshetye _______________________________________________ nupic mailing list [email protected] http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org _______________________________________________ nupic mailing list [email protected] http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org
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