Physiological and sensorial determinism of maternal behaviour in mammals

In mammals, the development of maternal behaviour is generally controlled b y neuroendocrine factors followed by sensory factors. Whereas the dynamics of the steroid balance at parturition are of primary importance in non-huma n mammals, stimulation of the uterine tract during the expulsion of the foe tus is the key-factor in ungulates, This induces a cascade of physiological events and particularly the activation of the oxytocinergic system. The in crease in prolactin release appears to be important only in rodents, Activa tion of the opiate system induces inhibitory effects in rodents and facilit atory effects in ungulates and, in rodents, the medial preoptic area is the central key structure of hormonal action. In women, no correlation exists between hormonal levels and maternal attitudes either during pregnancy or i n the post-partum period. Physiological factors enhance receptivity to stimuli coming from the neonat e and this allows the female to display maternal behaviour beyond this crit ical period. Odours facilitate the organisation of both maternal and infant ile behaviour and are involved in individual recognition for both. Olfactio n may also participate in the regulation of mother-young interactions in hu mans.