Yehouda Harpaz
yh@maldoo.com
9 Sep  94
www:            http://human-brain.org/cognition.html
		                         hypotheses.html
 related texts 

1. Each cognitive element corresponds to large number of neurons, which are distributed over large regions of the underlying physical System. The number of neurons corresponding to each cognitive element is small compare to the number of the neurons of the whole System.

2. Cognitive elements cannot be moved, transferred, sent, retrieved, accessed or broadcast in the System. They 'live' only in the same 'location' (neurons) where they were created, they can only be activated/de-activated, and affect the rest of the System by activating other elements.

3. The operations of the brain are mediated by many micronodes, and the overall effect is not dependent on any specific micronode, or on the exact parameters of each micronode.

4. Over some level of activity in the System, the inhibitory signal in the System grows much faster the the activating signal. This restrict the activity of the System to this level, as any additional activity will cause much more inhibition than activation. This level of activation correspond to a small number of cognitive elements. At this level of activation, only micronodes which receive relative large number of activating signals will become (and stay) active.

5. The global nodes carry very simple operations. Their output is simple, typically a single continuous variable, and the dependency on the input is not much more complex than weighted integration. In particular, they do not carry processing at the level of cognitive elements.

6. The System is continuously active. If there is not sensory input, the activity mostly will follow from previous activity (== the person will continue to think on the same subject). If the activity become very low, random activation of Maintenance operations (below), and sometimes of just random sets, will cause the System to 'change the subject' (== activate micronodes unrelated to the current active nodes). Motor actions, including speech production, are generated as part of the flow of activation, by sending activation to motor centers.

7. The set of micronodes corresponding to a cognitive element cannot, in most of the cases, be grouped by other features, apart from some localization in self-sustaining sets. In particular, micronodes are not necessarily localized, and there is no necessary pattern of connection between micronodes in the set (It is even possible that there are separate 'islands' of micronodes, which are not connected at all to other micronodes in the set). In other words, cognitive elements are an interpretation of the System, and do not correspond to any physical structure.

8. the implementation of Episodic Recall System (ERS)

   The ERS is made of a large subset of the cognitive system ( 1--50 % of the total micronodes). All of these micronodes get input from a center, which is controlled by a smaller set (the size of a cognitive element). The center control the level of activation in the ERS, and can also attenuated the activation signals from and to micronodes in the ERS. The inhibitory effect of the micronodes of the ERS on the rest of the System is very weak.

   In normal operation, the center of the ERS keeps active relatively small number of micronodes (0.0001-0.01 of the total in the ERS). These micronodes do not have any specific pattern. This can be done by keeping the micronodes just below threshold level, and by attenuating down the activation into the ERS

   As a result, at any moment some of the micronodes in the ERS are active. These micronodes constitute the episode set. The strength of the connections between the episode set and the other active micronodes in the System is increased, and also the connections inside the episode set. Since the micronodes which constitute the episode set are continuously changing, the episode set of any point in time is overlapping with both the preceding and following episode sets, and there are strengthen connection between the non-overlap micronodes of two neighbouring episode-sets.

   When the System need to do an episodic recall from the immediate past (e.g. Recall words from a list shortly after it was read), it does this by:

   1. attenuating the sensory input.
   2. Increasing activation in the ERS.

   As a result, activation will spread from the current episode set to the preceding episode sets. This will send activation to the sets that were active at preceding time. If these matches the activation from the other cues (words, medium of input, etc.), these sets will become active (== the corresponding cognitive element will be recalled).

   The activation in the ERS can continue to flow backwards(3), to recall more sets, but there is nothing that directs it to go only backwards in time. As a result, the activity become very diffused, and completely episodic recall cannot go much back in time. However, there are always additional cues active in the System, and the activation from these cues gives preference to the appropriate micronodes.

9. procedural knowledge and automatic motor operations are subsets of cognitive automatic operations. An automatic operations activate motor actions by sending activation to the motor control centers in the brain. Procedural knowledge of how to do something corresponding to an automatic process which activate the appropriate actions (both cognitive and motoric).

10. The control of thinking is mediated by automatic operations. An automatic operation is fast moving activity, where each micronode is active for a short time. This happen because these micronodes are connected such that each step in the operation send many activation signals only to the next step, relatively large inhibition to previous steps and to itself, and little signal to the rest of the system. I will call groups of micronodes connected this way Automatic Operators.

11. The System favour instances of activation flow (whether random or not) with cognitive positive outcome (defined in the next Hypothesis) by repeatedly 're-living' them, i.e. following the same flow of activation again and again.

12. Major part of the learning of automatic processes is done by continuous activating micronodes in the ERS at random, and allowing activation from the ERS. This leads to activation of various episode sets (mostly mixtures), to activation of the corresponding micronodes in the rest of the System, followed by spread of activation. In part of the cases, this flow of activation will cause a slow down (close to a halt) in the random activation of micronodes in the ERS. As a result, the pattern of activity in the ERS does not change, causing the repeated activation of the same flow of activation. The slowdown of random activation of the ERS is the Cognitive Positive Outcome.

13. Imagined pleasant Sensory input is a cognitive positive outcome, i.e. cause slow down of random activation of the ERS ('pleasant' stands for the normal definition of the word). The imagined input is a result of connections between micronodes in the System and neurons in the input systems, which are forms only when the real pleasant input happen.

14. large positive change of activity (detected by the Pattern Match node) is a cognitive positive outcome.