A reader, Kent Schnake, sent me a link that looks very good - it's to Dialogues in Clinical Neuroscience, which appears to be open access, for past issues, anyway.
Here is a link to the 2004 issue on neuroplasticity. In it is an article by Fred Gage, downloadable.
Here are some posts that have included discussion of Fred Gage's work:
1. Nervous System Basics VIII: PLASTICITY
2. History of Neuroplasticity