Dear Xingbao,

I do not think that you did anything incorrect in your analyses.  Results from Bayesian model selection can differ between SPM5 and SPM8 because they use different approximations for the log evidence.  BMS in SPM5 is based on AIC/BIC whereas in SPM8, BMS uses the negative free energy (F).  The critical difference between these approximations is how they define the complexity of a model.  For example, AIC/BIC only take into account the number of model parameters, regardless of the degree of interdependence amongst these parameters.  In contrast, F does consider such interdependencies (and has some other properties), which, in most instances, renders it a more appropriate measure of the complexity of a model.  For this reason, all model comparisons in SPM8, whether for DCM or other applications, now use F.  (For a full discussion of the relative advantages of F and AIC/BIC see our recent random effects BMS paper).

Because of these differences in defining complexity, BMS results can differ when using SPM8 versus SPM5.  This is not necessarily the case (for my interhemispheric model, for example, the model rankings are identical for F and AIC/BIC), but it is possible.  As long as you clearly describe which approximation you have used, you can use either F or AIC/BIC; the informed reader will then know what assumptions your BMS procedure is based on.  And concerning your final question: yes, of course, you can still cite the older DCM papers that used AIC/BIC. 

All the best,
Klaas