 The maintenance of fear has been shown to include the HPA axis, the locus coeruleus-noradrenergic systems, and the connections between the limbic system and frontal cortex.The HPA axis that coordinates the hormonal response to stress, which activates the LC-noradrenergic system, is implicated in the over-consolidation of memories that occurs in the aftermath of trauma.This over-consolidation increases the likelihood of one's developing PTSD.