Event-recurring multiband SWIFT functional MRI with 200-ms temporal resolution during deep brain stimulation and isoflurane-induced burst suppression in rat

Purpose: To develop a high temporal resolution functional MRI method for tracking repeating events in the brain. Methods: We developed a novel functional MRI method using multiband sweep imaging with Fourier transformation (SWIFT), termed event-recurring SWIFT (EVER-SWIFT). The method is able to image similar repeating events with subsecond temporal resolution. Here, we demonstrate the use of EVER-SWIFT for detecting functional MRI responses during deep brain stimulation of the medial septal nucleus and during spontaneous isoflurane-induced burst suppression in the rat brain at 9.4 T with 200-ms temporal resolution. Results: The EVER-SWIFT approach showed that the shapes and time-to-peak values of the response curves to deep brain stimulation significantly differed between downstream brain regions connected to the medial septal nucleus, resembling findings obtained with traditional 2-second temporal resolution. In contrast, EVER-SWIFT allowed for detailed temporal measurement of a spontaneous isoflurane-induced bursting activity pattern, which was not achieved with traditional temporal resolution. Conclusion: The EVER-SWIFT technique enables subsecond 3D imaging of both stimulated and spontaneously recurring brain activities, and thus holds great potential for studying the mechanisms of neuromodulation and spontaneous brain activity.