Coupling
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<i>Coupling</i>
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The presence of a nervous system in a living system does not entail a change in the nature
of the operation of the living system as a structure determined autopoietic unity; it
implies only an enlargement of the domain of possible states of the living system through
the inclusion of structure determined relations of relative neuronal activity in the
autopoietic network. The observable effectiveness that the relations of relative neuronal
activity have for the realization of the autopoiesis of a given organism in its medium is
the result of the structural coupling existing between the nervous system and the
organism, and between these and the medium.
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The argument for structural coupling of autopoietic systems can be summarized as follows.
Given that the interactions of a composite unity in the space of its components are
interactions through its components (that is, are structural interactions), if, as a
result of a structural interaction, the components of a unity or their relations change,
the structure of the unity changes and, if this structural change occurs without a change
in the organization of the composite unity, the identity of the unity remains invariant. A
composite unity whose structure can change while its organization remains invariant is a
plastic unity, and the structural interactions under which this invariance can be
sustained are perturbations. Since it is a constitutive feature of an autopoietic system
to maintain homeostatically invariant its organization under conditions of structural
charge, the realization of the autopoiesis of a plastic living system under conditions of
perturbations generated by a changing medium must result in the selection of a structure
in the living system that incorporates, in its autopoietic network, specific processes
(changes of state) that can be triggered by specific changes of state of the medium;
otherwise, the system disintegrates. The result of establishing this dynamic structural
correspondence, or structural coupling, is the effective spatiotemporal correspondence of
the changes of state of the organism to the recurrent changes of state of the medium,
while the organism remains autopoietic.
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The same general argument can be applied to the nervous system in particular. The
organization of the nervous system as a closed network of interacting neurons must remain
invariant, but its structure may change if it is coupled to the structural change of other
systems in which it is embedded, such as the organism, and through this, the medium in
which the organism exists as an autopoietic unity, or, recursively, itself. If the
structure of the nervous system changes, the domain of possible states of relative
neuronal activity of the nervous system changes, and, hence, the domain of possible
behavioral states of the organism itself changes, too. Therefore, if as a result of the
structural changes of the nervous system the organism can go on in autopoiesis, the
nervous system's changed structure may constitute the basis for a new structural change,
which may again permit it to go on in autopoiesis. In principle, this process may be
recursively repeated endlessly throughout the life of an organism.
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That the ontogenic structural coupling of the nervous system to the organism, to the
medium, and to itself should occur through recursive selective interactions is an
epistemological necessity. Which interactions select which structural change in a
particular nervous system depends on the particular case under consideration. There are
well-documented examples that I will not describe, but I will add that to the extent that
the nervous system operates as a closed neuronal network its actual operation in the
domain of relations of relative neuronal activities could not lead in it to second-order
structural changes. However, since, in addition to their participation in the closed
neuronal network that the nervous system is, neurons exhibit properties common to all
other cells, neurons can be perturbed chemically or physically by the products of other
cells of the organism, whether or not they are members of the nervous system, or of the
medium. These perturbations, which are operationally orthogonal to the domain of relations
of neuronal activities in which the nervous system operates, may trigger structural
changes in the neurons that result in second order structural changes in the nervous
system that result in changes in its domain of states that result (for the observer) in
changes in behavior. Since these orthogonal perturbations constitute selective
interactions, structural selection must take place through them in the domain of potential
structural diversity constituted by the domain of perturbations of the organism, and it
must take place through the spatial and temporal concomitances of chemical and physical
neuronal perturbations determined by the structure of the media in which the nervous
system is embedded. At this point it should be apparent that the only structure of the
nervous system that allows for this sort of structural change is that in which the nervous
system operates as an homeostatic closed neuronal network that generate, and maintains
invariant relations of relative neuronal activity that are selected, through interactions
orthogonal to this domain of operation, by the actual realization of the autopoiesis of
the organism that it integrates.
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While autopoiesis lasts,
<i>(a)</i>
continued ontogenic structural coupling of the nervous system selects the neuronal
network structure that generates the relations of relative neuronal activity that
participate in the continued autopoiesis of the organism in the medium to which it is
coupled; and
<i>(b)</i>
the structural coupling of the nervous system to the organism, to its medium, or to
itself that adequate behavior (interactions without disintegration) reveals may appear to
an observer as a semantic coupling, because he or she can ascribe functional significance
or meaning to any behavior, and can describe the underlying physiology as if caused by
these semantic relations.
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