As the understanding about perception and cognition deepens, the typical strategy of modeling the BOLD response with a presumed response curve with a fixed shape (same across brain regions, across all sorts of tasks or conditions, across subjects and groups) may become unable to reveal the nuances of brain responses. Instead accurately modeling the BOLD response could be necessary, and the adoption of multiple basis functions in characterizing the temporal change of the brain response could be better appreciated. The alternative approach of taking effect estimates at multiple consecutive time locations to group level has been generally considered very difficult, but that seems to be partially a misconception. As more group analysis approaches become available, the hurdles are not really insurmountable, and the major inconveniences at group level, compared to modeling the BOLD response with an inflexible shape, are the following:

1) One extra explanatory variable for the time locations needs to be modeled.

2) One may, but not always, need to use an obscure and computationally heavy program such as 3dLME (currently under beautification) or 3dMVM (soon to come). Surprisingly sometimes 3dANOVA3 can even handle it easily.

3) Visualization of the group effect is a little bit more strenuous.

See more discussions here:

[afni.nimh.nih.gov]

Gang



Edited 5 time(s). Last edit at 10/22/2012 10:15AM by Gang.