Take some ketamine :) ... I'm stating this as someone with first hand experience, so it may seem hand wavy and "made up": memories are visual and those visuals directly trigger your nervous system which then responds and often impacts the visual memory replay (often cutting it off or moving to something else). Your nervous system is also constantly telling your visual system what to "lookup". Ketamine dissociates the nervous system from visual memory so you can sort of play the memory through like a spectator. I think this is why it is so effective at treating things like PTSD -- the memories are often so frightening or triggering to the nervous system that they cannot be replayed, understood and integrated... but with Ketamine cutting off the nervous system they can be understood without a panic attack or heart rate shooting through the roof.