Read with caution!
This post was written during early stages of trying to understand a complex scientific problem, and we didn't get everything right. The original author no longer endorses the content of this post. It is being left online for historical reasons, but read at your own risk.
I found this article which may be of some use – “The basics of preclinical drug development for neurodegenerative disease indications”
The most useful part is probably the section at the end that discusses funding sources for preclinical drug development.