Chapter 24
The Nervous System
The brain is a living exemplar of an information processor par excellence. It seems,
therefore, obvious that bioinformatics encompasses the study of the brain, although
it is often considered quite separately. Because of the immense literature about the
brain, this chapter will only offer a few brief insights.
The fundamental need for a brain arises because of the need of a living organism
to coördinate its actions 1; directive correlation implies that purpose-like behaviour
requires a minimum number of causal connexions and this number is very large if
activities are to be coördinated. Perfect coördination (of an activity) can be defined
as implying that the activity takes account of all other activities. Even a very simple
animal movement with focal condition FC (cf. Fig. 3.2) might require four muscles
to be coördinated; denoting the state of excitation or inhibition of these muscles by
the variablese 1 comma e 2 comma e 3e1, e2, e3 ande 4e4, and considering that the reaction timerr of each muscle
in taking account of any of the others is uniform and constant, the causal connexions
for any particular epoch are shown in Fig. 24.1.
A similarly perfectly coördinated system of nn muscles would require tilde n squared plus n∼n2 + n
causal connexions; in practice an even greater number would be required because
our variables ee require both afferent and efferent connexions and further con-
nexions would be required for the sake of adaptation to particular environmental
circumstances.
Given this swift increase in complexity with size, there are evident advantages in
making the connexions permanent, narrowly canalized and lacking mutual interfer-
ence: a nerve system is able to satisfy these requirements. There is a further great
advantage in centralizing the system as in Fig. 24.2, in which the circle represents
the boundary of the nerve centre. The sixteenfold connectivity is now confined to the
1 Sommerhoff (1950), Sect. 31.
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J. Ramsden, Bioinformatics, Computational Biology,
https://doi.org/10.1007/978-3-030-45607-8_24
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