the stuff that you have worked on to try tot erase memories or stimulation of the brain using opto genetics controlling the activity of neurons that is almost certainly the most precise of any of those mechanisms, i think. the challenge there is going to be getting it into humans because it requires brain surgery and gene therapy to put this in your neurons so it is scary. so in terms of something that is both to being applicable. i think the kind of techniques that you have worked with such as reconsolidation, which is where you basically cause a memory to be reactivated and then use what we know about memories to disrupt that memory. because we have learned from people that memories become unstable whenever you retrieve them and you can actually kind of cause them to be degraded. and i think that that technique is still not ready for prime time either, but it is certainly the least of science fiction of all of them. >> also the least invasive. but i agree with you, i think that there are several different typesnt of memories, how do we know it's active in the human brain without any techn