Neocortical and other modulating influences on the "immobility reflex."

Abstract

This study was undertaken to determine the influences of the neocortex on the neural mechanisms involved in the immobility reflex (animal hypnosis). Phylogenetically, an inverse relationship exists between the relative development of the neocortex and susceptibility to the Immobility Reflex (IR). The role of the neocortex in the IR was studied ontogenetically, surgically, genetically and pharmacologically. In studying the ontogenetic influences in rats from birth until two years of age, newborn rats were found to be susceptible to the IR and this susceptibility progressively decreased until they were fifteen days of age. A percentage of young adult rats had a low degree of susceptibility. There was a progressive increase in IR duration and the percent susceptible, and a progressive decrease in induction time in older rats. ...