How do you launch a main .m file with a GUI push button?

I am trying to link a main .m file (Research.m) with a GUI built with GUIDE. The user will browse their computer for a filename. Once the filename is selected, I want to use that filename in the main .m file. How can I link these? Do I use assignin?

[OCDER]

Can you upload the Research.m file? Does it take an input for filename? Ex:

%Research.m
function out = Research(filename)
   ...
end

Don't use assignin as you'll run into debug nightmares later on.