Physiological aspects of the "defence" and "defeat" reactions.

By means of tele-receptor signals (vision, hearing, olfaction) the mammalian brain is almost continuously informed about environmental events, and whenever these are interpreted as positive or negative challenges the cerebral "super-controller" can, for coping with the anticipated situation, select the most appropriate among a number of pre-formed hypothalamic reaction patterns. These are organized as combined engagements of the somatomotor, visceromotor and hormonal efferent links, whereby a variety of behavioural responses can be elicited, where each is accompanied by appropriate adjustments of inner organ systems, metabolism, etc., to achieve optimal performance. For eons of time these "emotionally charged" reactions, common for all mammals, have served to protect the individual and species in a merciless environment, and they certainly remain principally the same also when Homo Sapiens faces modern society. As then the ancient "defence" and "defeat" reactions, intended for quite different situations, are often activated by the many artificial stimuli and symbolic threats inherent in today's hectic and competitive life, their principal organisation and functional consequences are the main topic of this survey. They are, for example, also marginally engaged along with ordinary shifts in mood during events in daily-life but are probably in this mild form fairly harmless and actually often supportive for efficient performance. However, when intensely engaged over longer periods they can, indeed, profoundly disturb inner organ systems and metabolic events, often resulting in disorder and even in premature death, as particularly convincingly shown by Henry and co-workers in studies on rodent "micro-societies". Transferred to man's situation in modern life, these model studies have been crucial for insight into the indeed complex mechanisms involved when long-term psychosocial stress in predisposed or particularly exposed individual contributes to some of today's most important "disorders of civilisation".