On nervous complexity and delays in reaction to stimuli
Nerve fibers are quite sluggish transmitters of signals. Therefore, an immensely complex nervous system such as that of a human being may need, for best functioning, to delay reactions to stimuli long enough for thorough processing. Otherwise the reaction, not making thorough use of the uniquely human nervous architecture, may resemble the reactions of an animal; and so we have such common expressions for undelayed reactions as ‘reptile brain’.
The mechanism of the unconditional reaction is, under ordinary circumstances, almost automatic. It is evolved on the background of general protoplasmic characteristics, combined with structural polarity, symmetry[, etc.], and is not efficient enough for the survival of higher organisms.
Under more complex conditions, the adjustment for survival must be more flexible: a similar direct stimulation must, under different conditions, result in different reactions, or different stimuli, under other conditions, produce similar reactions, resulting, ultimately, not only in direct responses to stimuli, but also in the equally important holding in abeyance of the reaction, or even the abolishing of it. Let us assume that the direct response of a cat to a mouse would be clawing and chewing. If that given cat would just claw and chew when the mouse was some distance away, I am afraid such a cat would soon starve, for such an immediate response would not be a survival response, and this characteristic could not become hereditary. The cats which have survived and perpetuated their characteristics are, as a rule, different. When they see, hear, or smell the mouse at a distance, they flatten out, keep still, crouch[, etc.], and get ready, until they are in such a position that a jump will procure the victim, and not merely frighten it away.
We see that, under more complex conditions, the nervous mechanism must produce not only direct responses to the stimuli but also equally important delays and temporal or permanent abolishments of these direct responses to stimuli.
chemoelectric) wrote, 