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Hello, I am afraid that Mathematics is not my strong point so although there are a lot of great article son DCM available most lose me by the second paragraph. I wanted to ask a few non- mathematical questions about DCM in the hope that someone could help me. Here is what I would like to know about DCM: Firstly for the intrinsic connections (DCM.A): 1. Does the strength of the intrinsic connections mean the speed with which a change in activity in one area produces a change in the other? 2. if the above is true, and the connection strength is lower in my group of patients compared to controls then what can I infer (in psychological terms)? Would it be fairer to say that information transfer is poorer in my patient group? 3. If the controls' connection strength was -0.3 and the patients' connection strength was 0.2 would it be valid to say that the connection is excitatory in patients and inhibitory in controls, and that controls show greater connectivity (as they have a higher absolute value for their connection strength)? 4. Which is the better formulation of what an intrinsic connection is, that it is the mean connectivity over all your conditions, or that it is the 'resting' connectivity (i.e. with no experimental input)? Secondly for the modulation due to the experimental manipulation (DCM.B): 1. Am I right in thinking that the value we get from the DCM.B for each subject is meaningless without reference to the baseline? An example where I am looking at the effect of attention on a connection might help. My DCM.B output gives me a value of -0.12 without attention and -0.32 with attention for controls and -0.12 without attention and -0.2 with attention for patients. I infer that attentional modulation is -0.2 for my controls (difference between attended and unattended connection strengths) and -0.08 for the patients. So do I spring to the conclusion that attentional modulation is higher for the controls (because the absolute value is higher?) or do I need to look at the baseline. If the patients' intrinsic connection strength is -0.3 and the modulation is -0.08 then maybe their connection is now greater (i.e. Even more inhibitory), while if the control's intrinsic connection was 0.2 and their modulation is -0.2 does this mean that the connection strength is now 0? Maybe I am completely wrong and a -0.08 difference in modulation would be a 0.08 decrease in connection strength with attention while a 0.08 difference would be 0.08 increase in connection strength? Any help (as non-mathematical as possible), would be brilliant. Thanks, Geoff