The work of Bruce Perry describes the neurological aspects in the development of attachment. His work describes how the brain stem develops first, followed by the midbrain, followed by the limbic system, and then the cortex. His work shows how emotional reactivity and regulation, and belonging and attachment occurs between the caregiver and the infant's midbrain and limbic system. He proposes that teaching attachment to an older child by cognitive means is not effective in the treatment of Reactive Attachment Disorder. he explains that using a cognitive approach mainly interacts with the cortex of the brain, and this is not where attachment behavior develops in the brain.
The limbic system includes the hypothalamus, the hippocampus, and the amygdala. This system is also important in dealing with trauma and traumatic memories. The hippocampus is responsible for sending memories to the appropriate part of the cerebral hemispheres for storage and retrieving these memories as needed. The amygdala is responsible for the formation of memories and our emotional life. It plays an important role in mediation, friendship, love and affection and the expression of moods. Additionally, it is the center for identification of danger, fear and anxiety, alertness, and the fight or flight response.