Semantics and Communication for Memory Evolutive Systems
Andrée Ehresmann & Jean-Paul Vanbremeersch
Page 4
Source: http://cogprints.org/2075/1/Baden-Baden_92.htm
5. Semantics and Communications
The development of the Memory relies on two distinct processes and their interplay : the usual memorization process (defined in 1989, 1991) leading to the empirical memory, simply called Memory, and the categorization process leading to Sem. To have more intuitive ideas, we take a neural network; the results are easily generalized to any MES.
- A pattern B is stored in the Memory through its cohesive binding B', so that each time B is activated, it is recognized through the activation of B'. Biologically, the memorization of the pattern B consists of the strengthening of its distinguished links, which transforms the pattern in a synchronous assembly of interconnected neurons in the concept of Hebb (1949). B' denotes this assembly, considered as a higher order unit in the Memory. For B' to be activated, it is necessary that the assembly as such be activated, so that all its components Bj are activated, and act synergistically through their distinguished links.
- The categorization process operates in parallel in the various CRs. For each CRn, it decomposes in 2 steps:
1. a local step consisting in the comparison of the constraints two patterns impose on the actors of CRn, to recognize if they have the same CRn-shape;
2. a more complex process directed by higher level CRs in which the whole class of patterns with the same CRn-shape is memorized by a unique concept in CRn-Sem, the concept being activated as soon as one of the patterns of the class is.
What are the consequences and the interactions of these processes on the communications between CRs which modulate the dynamics of the system? It will recognize constancies through changing circumstances and react in a specific manner not to a particular situation but to all similar situations; for instance an object is identified whatever be its size or location in the visual field. In particular the procedural Memory Strat (cf. our paper in Baden-Baden 1991) relies on invariances: what counts in a strategy is not which pattern of the landscape is activated but what command the actors transmit to the effectors. So it is the induced pattern of actors which is important, and strategies will be chosen and memorized in terms of CRn-concepts (we have developed this point in our 1992 paper). It follows that the choice of a strategy does not force the explicit patterns which are activated in the Memory or the effectors, as long as they have the same shape. This latitude confers a great flexibility to the model. If a strategy requires the activation of a particular concept in Sem, it activates the induced pattern A of actors; which pattern B representing the concept will be activated depends on the context.
As the different CRs all cooperate (eventually with conflicting strategies) in the dynamics of the system, the choice by one of them, say CRn , of a strategy will have a different result according to the choices of the other CRs. It explains that a strategy in the procedural memory acts as a 'frame' in the sense of Minsky (1986), where 'slots' may be differentially filled depending on which choice of B the situation requires. For instance, the order to hold an object will not activate the same muscles depending on the location of the object, on its size, its shape,... .
Physiological data explain how the activation of a CRn-concept G is reflected into that of a specific pattern B in its class, though there is no direct link from G = snB to B (there is only a link in the other way). G activates the pattern of actors Ai of which it is the limit, and the process of selecting strategies increases the attention in a diffuse way, so that the activity of all the patterns B (either in the receptors or the Memory)
having G as their concept will be increased. Then, following Hebb (1949), the strength of the synaptic links from B to Ai also increases, its two ends increasing. This increases the activity of B through a feedback from the post-synaptic neuron Ai to the pre-synaptic neurons Bj (synapses transmit prediction and information via NO fluxes, cf. Schuman & Madison 1991). In this way, the B which receives the more inputs from other sources will be activated by G.
As will be shown elsewhere, this process explains how behavior will become more and more adapted, since the occurrence of fractures may force the actors to distinguish which specific pattern must be activated in a particular context. For instance, in the development of language by a child, terms take a more precise meaning as the experiences accumulate. It also explains how several types of neural degeneracy, such as aphasies or apraxies, depend on the severing of communications between specific CRs, so disrupting the transmission of activities between a pattern and its concept or reciprocally.
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