New Software: HRFun (OS X)

I have been spending a fair amount of time learning the Objective-C programming language lately. While I spend most of my time in Matlab, I am thinking about writing some Mac OS X applications in the future. For those of you who are looking to do the same I can highly recommend the Aaron Hillegass book “Cocoa Programming for Mac OS X” as a good way to get started. I will go into the learning Objective-C in another post, but wanted to take a second to announce the first complete fruit of my learning labor: HRFun.

HRFun is a small Cocoa application that allows a user to explore the construction of a canonical hemodynamic response from the summation of two gamma functions. This is the method used by the Statistical Parametric Mapping (SPM) folks to model what happens in the brain when a stimulus is applied. For instance, if I show a brief flashing checkerboard pattern to a subject while conducting functional MRI then areas of visual cortex would have signal changes similar to the canonical HRF. I was curious about how varying the parameters of the gamma functions would change the predicted hemodynamic response, so I created this application that lets me vary any parameter I want.

It’s not a terribly useful app, but for those who are curious to learn more about the SPM construction of a canonical HRF it can be a useful tool. HRFun is my first OS X application to be released, so there are probably some inefficiencies and bugs in the code. Still, I have been diligent to test the software out and smooth the rough edges. Also, the source code has been released under the GPL. So, if you need an Objective-C class to create a hemodynamic response you’re in luck!

Let me know what you think – positive or negative. This is a learning project, so any feedback is appreciated. My next goal is to figure out how to load an fMRI timeseries – then the real fun begins.

HRFun wiki page: http://prefrontal.org/wiki/index.php/HRFun

August 23, 2008 • Posted in: CogNeuro, MRI

Leave a Reply