EMDR works by connecting both sides of the brain in a way that is similar to what happens when dreaming.  When dreaming, the eyes move back and forth which helps process through emotional content.  In an EMDR therapy session, the therapist will use techniques to provide bilateral stimulation (by providing a visual focus that requires a person to move their eyes back and forth, by using tones played in alternate ears, or by tapping alternating sides of the body).  This bilateral stimulation helps the brain reprocess past events and memories that are distressing.  EMDR promotes healing by clearing neural pathways so the flight, flight or freeze response from the original event becomes resolved.  Unlike traditional talk therapy, EMDR doesn't rely on talking through every detail of the situation.  Instead EMDR, uses bilateral stimulation to change the brain so the event or memory is no longer traumatic.