Neuromag July 2018 - Page 9

Pregnancy and the Brain: Behavioral and neural adaptations in a sensitive transition period Written by Elisa Rehbein and Ilena Bauer The University of Tübingen and the University of Uppsala are carrying out a study in which maternal and fetal changes during pregnancy and the infants’ development after birth are investigated. This will shed light on a sensitive phase where all of our life started. Pregnancy is a crucial period for wom- en and is associated with behavioral and neuronal adaptations presumably preparing them for the protecting and nurturing demands of motherhood. The origins of altered brain anatomies associated with major mental dis- orders are assumed to already take place during the intrauterine phase. It is important to not only address the impact of pregnancy on the expecting mothers, but on fetal development, child behavior and mother-child in- teraction. It is necessary to shed more light on this critical period in a wom- an’s life that not only shapes her (and her brain) but also lays the foundation for her child’s health. While data on how pregnancy and as- sociated fluctuations in sex hormone levels affect brain function and struc- ture in animals has been collected throughout the last decades, evidence on the impact of human pregnancy on behavioral – but more interestingly – neuronal adaptations is scarce [1]. Sex hormones are known to act as an important regulator of neuronal mor- phology. Not surprisingly, other en- docrine events involving less extreme and rapid fluctuations in hormone levels than pregnancy are known to render structural and functional alter- ations in the human brain. The produc- tion of gonadal sex hormones during puberty for example regulates an ex- tensive reorganization of the brain [2]. period and follows a rapid, orches- trated chain of partially overlapping ontogenic events. It is highly likely that the intrauterine milieu can influ- ence neurodevelopmental trajectories. These effects may independently, or in conjunction with other factors, impact subsequent long-term susceptibility for various neuropsychiatric disorders. Moreover, neural alterations have also been observed in response to even subtle changes in endogenous or ex- ogenous sex hormone levels later in life [3]. Growing evidence has accu- mulated that the origins of structural alterations characterizing mental and neurodevelopmental disorders can be traced back to the intrauterine period of life. During this period the develop- ing fetus (and its brain) is influenced by environmental conditions during sensitive periods of cellular prolifera- tion, differentiation, and maturation to produce structural and functional changes in brain and peripheral sys- tems i.e. fetal programming [4]. Hu- man brain development begins early in gestation, occurs over a protracted The Neuronal Emotion Regulation Network in Pregnancy While the influence of fluctuating hormonal levels, such as during the menstrual cycle, are known to render structural and functional alterations in the human brain, knowledge of changes during pregnancy are surpris- ingly scarce [5]. However, recently a study has shown long lasting changes in brains of mothers in which reduc- tions of grey matter were still visible 18 months after they had given birth [6]. Thereby, they were able to predict which of the women that took part in their study were pregnant with up to 95.6 % accuracy. Interestingly, reduc- tions of brain matter lay in areas July 2018| NEUROMAG | 9