1.1 --- a/org/intro.org	Tue Feb 28 14:13:56 2012 -0600
     1.2 +++ b/org/intro.org	Thu Mar 01 05:56:52 2012 -0700
     1.3 @@ -125,10 +125,10 @@
     1.4  ago, and as a result it has been ported and modified for many
     1.5  different reasons. This engine was famous for its advanced use of
     1.6  realistic shading and had decent and fast physics
     1.7 -simulation. Researchers at Princeton [[http://papers.cnl.salk.edu/PDFs/Intracelllular%20Dynamics%20of%20Virtual%20Place%20Cells%202011-4178.pdf][used this code]] ([[http://brainwindows.wordpress.com/2009/10/14/playing-quake-with-a-real-mouse/][video]]) to study spatial
     1.8 -information encoding in the hippocampal cells of rats. Those
     1.9 +simulation. Researchers at Princeton [[http://papers.cnl.salk.edu/PDFs/Intracelllular%20Dynamics%20of%20Virtual%20Place%20Cells%202011-4178.pdf][used this code]] ([[http://brainwindows.wordpress.com/2009/10/14/playing-quake-with-a-real-mouse/][video]]) to study
    1.10 +spatial information encoding in the hippocampal cells of rats. Those
    1.11  researchers created a special Quake II level that simulated a maze,
    1.12 -and added an interface where a mouse could run around inside a ball in
    1.13 +and added an interface where a mouse could run on top of a ball in
    1.14  various directions to move the character in the simulated maze. They
    1.15  measured hippocampal activity during this exercise to try and tease
    1.16  out the method in which spatial data was stored in that area of the