Mechanisms of activation of maternal behaviour in mammals.

In mammals, the activation of maternal behaviour depends on internal maternal factors related with parturition. The nature of these factors may vary between species, although oestradiol, foetus expulsion and intracerebral oxytocin are the most commonly encountered. They induce a period of specific receptivity to some sensory cues provided by the neonate. These cues (tactile, olfactory, auditory, ...) also vary between species. The interactions between the mother and her progeny during this period, known as the sensitive period, facilitate the maintenance of maternal responsiveness beyond the initial phase of activation by the factors internal to the mother. The ability of mothers to display a well-adapted maternal behaviour is also modulated by maternal experience gained at the first parturition. Furthermore, this capacity is also influenced by the nature of the interactions experienced in infancy with the own mother of the female, which can lead to a non-genomic transmission of some individual characteristics of maternal behaviour or sensitivity to stress across generations.