|
Dong, Dawei Spatiotemporal decorrelated activity patterns in fMRI data associated with real and imagery motor tasks
We present a new method for separating multiple spatial patterns and associated time-courses of task related fMRI signals and multiple spatial patterns and associated time-courses generated by other physiological and physical events. Assuming that all the fMRI responses are linear and different spatial patterns are from independent sources, it is possible to separate them by decorrelating the responses into several channels, which are spatially as well as temporally decorrelated. We derived a closed-form solution which DOES NOT assume the non-Gaussian distribution of different signal sources. The method was used to analyze fMRI data sets from subjects performing 5-minutes trials composed of alternating 30-seconds motor (real or imagery) and control task blocks. We found not only the classical activation patterns of primary motor cortex during real motion and of supplementary motor area during imagery motion but also other task related patterns as well as other physical and physiological patterns. For example, we found an activation pattern in auditory area which was consistent with the time course of the auditory instructions given to the subject, and yet distinguished from the activation of the overlapping area which was activated in sync with the motor task. We aslo found other patterns such as slow changes probably associated with heads drifts. The result is shown for one trial, which was real motor blocks alternating with no-motion blocks, with verbal instructions at the beginning of each block: several separated time courses are shown in Figure 1 and the associated spatial patterns are shown in Figure 2.
|