Reaction of the organism to stress: the survival attractor concept.

This paper outlines a phenomenological approach for describing physiological reactions occurring immediately after vital threats. This exemplified by data taken from previous studies relative to chemical intoxications of rats by a neurotoxical drug. The survival rate of the animals and the variations of their cerebral acetylcholinesterase activity are both reported as a function of the drug concentration, and with respect to their age. The collecting of the results may be described as the cusp, a bifurcation set of Thom's Catastrophe Theory. The young animals react by a vital burst which modifies the shape of the cusp. A new fold or pocket takes place, changing it to the butterfly bifurcation set. This pocket supports the survival attractor concept, which appears reactional, transitory and variable in its intensity. In the last part of the paper, an extension of this concept is proposed to the visual domain. Some of patients who have suddenly and partially lost their visual acuity can recover some visual capacity by developing a new ability to see in weak contrasts. This reaction may be described as a visual survival attractor.