our minds are very complex and maybe somewhere in the background it is working on projects we arent really aware of.. when we see or hear a thing in the area nearby it might make contact with that inner, invisible work we are doing.. the memory might start to return but our mind has constructed such a safety net that we block ourselves from experiencing the images associated... im no pro, but perhaps the tear gland is triggered and the images and associated emotions are blocked as a matter of subliminal self protection, like the way our brain knows when to breathe without being told... the industry is spending a lot of time to find the exact answers to your questions and without dedicated, highly trained professionals, we would likely never receive the documented truths ......