More than likely something is going on from the changes to the active neural circuitry. Usually the "Default Mode Network" is active. When this is quieted down, which is similar to what happens when you're on LSD, it's possible that very unusual states of mind and body (the "currents" mentioned, which I've experienced as well) can arise.
That's a really good question and I worry about that myself. I think it might be incorrect to think that there is a "true self" inside you. More realistically I think there are many autonomous modules in your mind that run when needed or called. Your ego is one of these modules. This fear of losing our drive is probably the ego doing self-preservation (for itself).
Meditation helps you to see when these different modules are acting "illogically". Being run or called when unnecessary. A good example is the fear of public speaking. Whichever module is running is based on instincts learned millennia ago. Now it merely hinders us. I very strongly believe that meditation will make you (anyone) more happy and content. I haven't gone as far as I'd like to with it because of this same fear of losing my drive.
