Biomedical Engineering Reference
In-Depth Information
organization and self-regulation, and circular causal feedback mechanisms in the
animal and the machine (e.g., robots). Some of these systemic principles and
perspectives were assimilated by computer/cognitive sciences and are credited
with being at the core of neural network approaches in computing. In addition to
the early emphasis placed upon the observed system, the importance of the ob-
server (see Figure 3) has to be considered.
Who will integrate the integrators?
—Margaret Mead
Heinz Foerster (10) recognized the need for a theory of the observer, i.e.,
description of the describer (see Figure 6). A strong case was made for the need
of a transdisciplinary synthesis of a representational framework that can con-
solidate the concept of self-reference and the meaning of cognition and commu-
nication within the natural and social sciences, the humanities, and information
science. Because the structure and function of a system cannot be understood in
isolation, cybernetics and systems theory should be viewed as two facets of a
single approach.
General system theory encompasses the cybernetic theory of feedback,
which represents a special class of self-regulating systems. In both cases, the
parts entail the structure and function of the whole and as such are not isolable.
Nonetheless, a fundamental difference exists between GST and cybernetics,
whereby the feedback mechanisms (see Figure 3) are controlled by local con-
straints in contrast to the free multilevel interplay of the network of reactions in
dynamic living systems. Moreover, the regulative mechanisms of cybernetic
systems are based on predetermined (fixed) structural feedback. This implies
that they are closed systems with respect to exchange of energy and matter and
as such do not have the essential characteristics of living systems whose compo-
nents undergo growth, development, and differentiation, which "shows the exis-
tence of a general systems theory that deals with formal characteristics of
systems, concrete facts appearing as their special applications by defining vari-
ables and parameters. In still other terms, such examples show a formal uniform-
ity of nature" (1). The concept embraced by GST is a broader one and is
responsible for the development of the modern studies of nonstationary struc-
tures and the dynamics of self-organization in our attempt to understand how the
pattern formation functions (see Part II, chapter 4, by Wuchty, Ravasz, and
Barabási).
In biology (as well as in behavioral and social sciences), one often encoun-
ters phenomena that are poorly explained by the inanimate system of physical
laws. When analyzing living objects (or behavior), the tendency is to use func-
tional attributes of the component parts and biochemical processes that are hier-
archically organized to maintain the integrity, development, and progression of
the system in question. This is not to suggest some vitalistic or metaphysical
