A Mother’s Presence is a Biochemical Off Switch for Fear Because of ethical concerns, it’s difficult to scan the brains of most children; it is certainly unethical to upset an abused child even further by presenting traumatic events during a brain scan. Scanning also presents logistical problems in children, since the child needs to remain perfectly still during the scan. It is possible, however, to study normal and abusive attachment in rats. Though rats learn about their mothers entirely through smell—seeing and hearing do not emerge until the rat pup is around two weeks old—rats are similar to children in that they have a biologically predetermined attachment system in the brain but must learn to identify and remember the caregiver.