Abstract

In the last decade, neurobiological studies have focused efforts on investigating the biological substrates (i.e., cerebral structures, neurotransmitters, and hormones) underlying parental attuned behavior to salient infant stimuli (i.e., infant cries), that plays an important role in child affective, social, and cognitive development (Venuti, 2007; Bornstein, 2002). Both human and animal studies have primarily focused on the neurobiology of mothers and have shown that subcortical and cortical cerebral structures such as the prefrontal cortex, thalamocingulate network, hypothalamus, amygdala, and substantia nigra are important in maternal motivation and attuned behaviors (Barrett & Fleming, 2010; Swain, Lorberbaum, Kose, & Strathearn,2007). However, there is a lack of literature concerning gender differences and only a few studies have investigated the sensitivity of response to infant stimuli in non-parent adults (Caria, de Falco, Venuti, Lee, Esposito, Rigo, Birbaumer & Bornstein, 2012; Glocker, Langleben, Ruparel, Loughead, Gur & Sachser, 2009; Parsons, Young, Kumari, Stein & Kringelbach, 2011; Montoya, Landi, Kober, Worhunsky, Rutherford, Mencl, Mayes & Potenza, 2012). In this research project we focused our investigations on mechanisms in human adults (parents and non-parents) involved in parental care, and in specific: (a) on neural mechanisms underlie BOLD response to infant vocalizations, crying in particular; (b) on brain changes (grey matter volume) occurring during the early postpartum period in new fathers. Using functional magnetic resonance imaging (fMRI), in the first study (second chapter) we looked at gender differences in resting-state brain activation associated with the cry condition at the default mode network (DMN) level in a sample of healthy adults (parents and nonparents). The design was balanced by parental status and gender. The DMN is preferentially activated when individuals are not involved in externally oriented tasks, namely during the mind wandering and it is deactivated during external goal-oriented activities. In the second longitudinal study (third chapter) we investigated in new fathers the GM volumes change amongst 2-4 weeks and 3-4 months postpartum in brain areas responsible for parental behaviors over time during the early postpartum period. Anatomical changes and their relationships with parenting behaviors have never been examined in human fathers despite the importance of paternal care for child development. In the third study (fourth chapter) we investigated, using fMRI and behavioral (Response Time RT) techniques, how the pattern of cerebral activation when listening to infant cry modulates concomitant behavioral tasks, which could require or not require the attention toward the cry stimuli, and thus affecting parental responsiveness.