There is an excellent survey on Neuroscience software, carried out by Yaroslav Halchenko and his colleague. Here is the result link: http://neuro.debian.net/survey/2011/results.html
The primary analyses have been published in: Hanke, M. & Halchenko, Y. O. (2011). Neuroscience runs on GNU/Linux. Frontiers in Neuroinformatics, 5:8.
I picked several figures from their result according to my research interests: