What is the mechanism or mechanisms behind "state-dependent learning"? If I'm better at a task while on a drug, will I also be better when I'm off the drug?

It's not a well formed question, but I hope to ask better ones as the view expands with more information.

Basically, I'm trying to answer the questions behind this thread. One of them is simply if I'm better at a task while on a drug, will I also be better when I'm off the drug? To analogize, if a bodybuilder or athlete supplements his training to improve his endurance, after training and off drugs, will he still have higher endurance?

One problem I see with comparing brain-training with state-dependent memory is that state-dependent memory refers to declarative and procedural memories; a task like N-Back doesn't seem to be procedural OR declarative, although that could be a dilettante's mistake.

At the same time though, if the gains at training persist over a certain time, then there has to be some sort of genetic mechanism -- protein signaling and peptides to spur on long-term synaptic changes. This is still the realm of LTP. But I don't know anything beyond that.

Argh. I need an EEG and some human guinea pigs. Or an education.