fMRI of deep brain stimulation at the rat ventral posteromedial thalamus

Background Functional magnetic resonance imaging (fMRI) of deep brain stimulation (DBS) has potentials to reveal neuroanatomical connectivity of a specific brain region in vivo. Objective This study aimed to demonstrate frequency and amplitude tunings of the thalamocortical tract using DBS fMRI at the rat ventral posteromedial thalamus. Methods Blood oxygenation level dependent (BOLD) fMRI data were acquired in a total of twelve rats at a high-field 11.7 T MRI scanner with modulation of nine stimulus frequencies (1-40 Hz) and seven stimulus amplitudes (0.2-3.6 mA). Results BOLD response in the barrel cortex peaked at 25 Hz. The response increased with stimulus amplitude and reached a plateau at 1 mA. Cortical spreading depolarization (CSD) was observed occasionally after DBS that carries >10% BOLD waves spanning the entire ipsilateral cortex. Conclusion fMRI is sensitive to the frequency effect of DBS and has potential to investigate the function of a particular neuroanatomical pathway.