http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3848041/

https://en.wikipedia.org/wiki/Valproate

Taking acetylcholinesterase inhibitors, also may increase plasticity: http://dana.org/Cerebrum/2012/Re-opening_Windows__Manipulati...

Here is a list of acetylcholinesterase inhibitors: https://en.wikipedia.org/wiki/Acetylcholinesterase_inhibitor...

There are a few other ways to potentially increase neuroplasticity:

Blood transfusions from young people or children to old people: http://www.nature.com/nm/journal/v20/n6/full/nm.3569.html

Transplanting inhibitory neurons: http://www.sciencedirect.com/science/article/pii/S0896627315...