See below.

Best Regards, 

Donald McLaren, PhD

On Thu, Apr 14, 2016 at 4:36 PM, Joelle Zimmermann <[log in to unmask]> wrote:

Hi SPMers,

I am looking at the relationship between neural activity and behavioral performance, and was hoping for some insight for correct interpretation of a particular analysis.

On the first level, I have a model with my fMRI signal (first column), my behavioral performance as a parametric modulator (second column), and my 6 motion regressors. I am interested in the behavioral parametric modulator, so I put a contrast over the second column.

When I forward these individual subject contrasts to the second level, and do a one-sample t-test to look at group, with t-contrast [-1], I find certain task-related regions show significance. Would it be correct to say that the behavioral performance modulates neural activity, with improvements in performance across time reflecting decreases in neural activity in these certain regions?

Yes.

 

Additionally, I conduct a 2-sample t-test, forwarding the first-level PM contrasts to the second-level, comparing young and old subjects. Here I find young>old gives me some interesting task-related regions. Am I correct to say that young adults' neural activations are more closely tied to behavioral performance than for old adults?

No. You can say that the slope of the relationship is different, but you can't conclude that the relationship is stronger as you only have the slope at the group level.

 

Thanks in advance,

Joelle