2.1. Participants and recruitment
Infants of families taking part in the FinnBrain Birth Cohort Study were recruited for an fMRI session through telephone calls. When the infants were aged 2-5 weeks, families were contacted to participate in the present study and interviewed by one of the authors. If at least one of the following criteria was detected in the interview, the mother infant dyad was not included in the study: occurrence of any perinatal complications with potential neurological consequences (e.g. hypoxia), less than 5 points in the 5min Apgar score, previously diagnosed central nervous system anomaly or an abnormal finding in a previous MRI scan (with clinical indications), preterm birth (delivery at less than 32 weeks of pregnancy or birth weight less than 1500 g). Demographics of mothers and infants included in the present study are reported in Table 1.
The study protocol was conducted in accordance with the Declaration of Helsinki and it was approved by the Joint Ethics Committee of the University of Turku and the Hospital District of Southwest Finland. Informed written consents were obtained from parents before MRI scanning sessions.