Phuong Hoa's question about functional connectivity with task-related data

Dear Dr. YAN Chao-Gan,

My name is Phuong Hoa, I am studying in Korea. I found your REST toolkit and I am interested in it.

Now I try to measure the functional connectivity from fMRI data with task-related (visual and motor stimuli).

I used ROI-wise with AAL template, but I saw all the correlation coefficient in the result is very high.

Does REST can analyze this kind of data? (Because I wonder REST is for resting-state analysis).

Best regards,
Phuong Hoa


Dear Dr. Phuong Hoa,

Thank you for using our software. REST can perform functional connectivity analysis including the task-related data. But whether you can perform the functional analysis on task-related data depends on which task you used. You'd better review papers in your field and confirm the significance to perform functional connectivity on such a task.

Best wishes!
                                                                          YAN Chao-Gan


Dear Tim, 
Thanks for your interest of REST. I am afraid I couldn't answer your question since I am not familiar with any task-related data. 
However, since what sit behind the function connectivity is Pearson correlation, you could just think REST is a tool which could do batch job of fMRI related Pearson correlation. The other need your exploration.
Best Regards,

2008/11/27 <>

Dear Song,
I downloaded your toolkit. First of all, thanks! It's a great tool. I wonder, however, if and how I could use it to assess task-related connectivity (blocked design). Is there any way to do this with your software? 
I think, what needs to be done is to concatenate all blocks of one condition and then proceed basically analogous to what you would do with resting-state data.
Thank you in advance.

Dipl.-Psych. Tim Hahn
Psychophysiology and Functional Imaging
Dept. of Psychiatry, Psychosomatics and Psychotherapy
University of Wuerzburg
Fuechsleinstr. 15
97080 Wuerzburg


 Hi Phuong,

I am not surprised to see you get high correlations. Here are some possible reasons. First, you used ROI-wise with AAL template, for both seed ROI and target ROI? AAL template regions are too large for seed regions. Better to use your thresholded task activation areas to generate seed ROIs. Also you need to do some preprocessing for the seed region time series, band-pass filtering, remove global mean, average etc. Then you can use the result time series to do connectivity analysis.

For task related studies, I really recommend to use Psycho-Physiological Interaction (PPI) analysis instead of normal functional connectivity analysis. PPI can give you not only correlated regions to a given ROI, but also interaction between psychological context and physiological input. You can find in literatures about this method. 

Good luck with your study! 



High correlation coefficient  in your results may be related to the task-induced effects. BOLD activation induced by task is commonly intensive than that from spontaneous neuronal activity, thus the signal will be a " BLOCK-designed"shape,  not a sine-like shape (of SNA). The correlation analysis mostly account for the "block" signal, rather than the lowfrequency fluctuation, therefore the cc will be higher.